properties of matter and solutions

/ 142 Slide 2 / 142

Properties of Matter and Solutions

Slide 3 / 142

Properties of Matter and Solutions

Pyrite, otherwise known as "fools gold" has fooled many a tourist

over the years. Physical and chemical properties such as

density or reactivity help us identify what substances are made of.

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Matter

We define matter as anything that has mass and takes up space.

Atoms of an element

molecules of a diatomic element

Molecules of a compound

Mixture of elements and a compound

Slide 5 / 142

What is Matter Made of?

Elements and Compounds

Substances that could not be broken down by any physical or chemical method were/are called elements

Substances that could be broken down into different elements using physical or chemical methods were/are called compounds

Element CompoundNe(g) CO2(g)Ca(s) CaCO3(s)Au(s) AuNO3(s)Hg(l) HgI(s)

Slide 6 / 142

Elements

Elements are found on the periodic table.

NaSodium

Cu-Copper

I-Iodine vaporAl Aluminum foil

Mg-Magnesium

C-carbondiamond and graphite

http://www.njctl.org

http://www.njctl.org

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Compounds

Compounds are formed by combinations of different types of elements.

CAFFEINE

Slide 8 / 142

1 Which of the following would NOT be a compound?

A HCl

B CS2

C H2O

D CH4

E I2

Slide 9 / 142

2 Which of the following is FALSE regarding compounds?

A They consist of more than one element combined

BA compound has a set of properties distinct from the individual elements from which it is made

CWhen a compound is separated into its elements, the elements will have the same properties of the compound

D Br2 would not be considered a compound

E NaCl would be considered a compound

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When electricity is passed through water (a compound), hydrogen and oxygen gas are produced.

100 grams 11.2 grams 88.8 grams

When the amounts of gases produced are analyzed, no matter where the water came from or how large the

sample, water always consists of exactly 11.2% hydrogen and 88.8% oxygen by mass.

electricity

liquid water ------------> hydrogen gas + oxygen gas

Law of Definite Composition

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In fact, each compound had it's own definite composition by mass.

Substance % carbon by mass

% oxygen by mass

carbon dioxide 27.3% 72.7%

carbon monoxide 42.8% 57.1%

This principle, that a certain substance will have it's own unique set composition of elements, is known

as the Law of Definite Composition.

Law of Definite Composition

Slide 12 / 142

Some matter can be separated by heat, filtering, or boiling into other substances but did NOT obey the law of definite composition. These substances are known as mixtures and are

NOT pure substances. More on mixtures later!

Pure Substance

Definitive Composition

Examples:

gold (Au)

pure water (H2O)

Mixture

Non-definitive composition

Examples:

steel (Fe, C, Mn, Cr, ...)

salt water (H2O, Cl-, Na+, ...)

Pure Substances vs. Mixtures

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3 A sample of material A is collected in Nevada and found to consist of 94% oxygen and 6% hydrogen by mass. Another sample of material A is collected in Maine and found to contain 94% oxygen and 6% hydrogen. What kind of substance is this?

A Element

B Compound

C Mixture

D B and C

E A, B, and C

Slide 14 / 142

4 A sample of a material is found to contain 56% oxygen, 32% iron, and 12% sulfur. When another sample of the same material is collected, the composition was 44% oxygen, 30% iron, and 25% sulfur. What kind of substance is this?

A element

B compound

C mixture

D pure substance

E B and D

Slide 15 / 142

Properties of MatterIt was clear, even to the ancients, that not all matter shares the same

characteristics/properties.

Substance Property

gold lustrous, soft metal, non-reactive, solid at room temperature

salt watertransparent, liquid at room

temperature, could be separated by heat, no definite composition

pure watertransparent, liquid at room

temperature, definite composition, could be separated by electrolysis

calcium carbonate

solid at room temperature, high melting point, non-lustrous, could

be separated by heat

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Physical Properties of Matter

A physical property is a characteristic that can be observed WITHOUT altering the identity of the material.

Physical Properties of water

water melts at 0 Celsius at standard pressure

water is transparent

water has a density of roughly 1 g/mL at 25 C

water is not soluble (does not dissolve) in gasoline

water is colorless

Notice all of these properties can be observed without changing the identity of the water - it is still water!

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Who doesn't like brick oven pizza! A brick used in an oven is made of a mixture of aluminum oxide and silicon oxide. Think of as many physical properties of a brick that you can. Feel free to use terms

like high and low if you don't know an exact number.

high density

high melting point

reddish color

brittle (break not bend)

move for answer

Physical Properties of Matter

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5 Which of the following IS NOT a physical property?

A copper has a reddish gold color

B iron reacts with oxygen to form rust

C table salt dissolves easily in water

D silver is an excellent conductor of electricity

E all of theses are physical properties

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6 Which of the following IS a physical property?

A acetone has a density of 0.87 g/mL

B aluminum will burn in air to make aluminum oxide

Cwater can undergo electrolysis and produce hydrogen and oxygen gas

D Both A and C

E Both B and C

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Physical and Chemical Changes

Chemical changes result in new substances.

Includes combustion, oxidation, decomposition, etc.

Changes in matter that don't change the composition of a substance.

Includes changes of state, temperature, volume, etc.

Physical ChangesChemical Changes

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These properties can only be observed when we attempt to

change the identity of the material. There are a few tell tale signs

that a chemical change has taken place:

Chemical Properties

Color change

Emission of Light

Precipitate formation

Production of gas

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Color change - marshmallow burning

Emission of Light - wood burning

Chemical Properties

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Precipitate formation - solid forming from liquid mixtures

Production of gas - when limestone is heated

+

+heat

Chemical Properties

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Compare the chemical properties of a pepperoni pizza with that of the brick oven.

The pizza will react with the oxygen in the air and burn. The

brick will not burn in the air. move for answer

Chemical Properties Class Discussion

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7 Which of the following is NOT a chemical property?

A Silver tarnishing into silver oxide

B gasoline burning in air

C candle wax burning

D candle wax melting

E iron rusting

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8 All of the following are physical properties except….?

A Gold's low reactivity with oxygen

B Gasoline's inability to dissolve in water

C Water melting at 0 C

D Hot knife cutting through ice cream cake

E evaporating water away from salt water

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9 In the following list, only __________ is not an example of a chemical change.

A dissolution of a penny in nitric acidB the condensation of water vaporC a burning candle

D the formation of polyethylene from ethylene

E the rusting of iron

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10 Which of the following are chemical changes?

A 2, 3, 4B 1, 3, 4C 1, 3D 1, 2E 1, 4

1. rusting of a nail

2. freezing of water

3. decomposition of water into hydrogen and oxygen gases 4. compression of oxygen gas

Slide 29 / 142

Properties of MatterApplication

When you cook, cheese can be melted or it can be burned. One is a chemical change, the other a physical change. Explain which

is which and how you knew!

melted burned

Melting is a physical change because the cheese has not changed - we know this because we see no evidence of a chemical change (no gas, light, precipitate, color change).

However, burning cheese is a chemical change because we clearly see a color change, taste change, production of a gas

when you set off the smoke detector!

move for answer

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Extensive Properties of Matter

These are properties in which the value depends on how much of the material is present.

Examples

The mass of a glass of water is 30 grams.

The stick has a length of 12.2 meters

The helium balloon has a volume of 14.7 liters

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Intensive Properties of Matter

These are properties in which the value is independent of the amount of material.

Examples

The water is transparent and colorless

The melting point of an iron chunk is 1538 Celsius

The specific heat (amount of energy required to raise 1 gram by 1 degree celsius) of aluminum is 0.89 J/g*C

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Intensive Physical Properties

Density is an excellent example of an intensive property. No matter the size of the sample, the ratio of the mass to the volume for a

given substance is the same. The higher the volume of the sample, the higher the mass will be.

mass of water volume of water density of water

19.01 grams 19.03 mL 0.999 g/mL100.43 grams 101. 01 mL 0.994 g/mL154.67 grams 155.74 mL 0.993 g/mL

note that the differences in density are the result of this being actual experimental data!

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Application and Class Discussion

Some meteorites found on the earth's surface are made of solid metal like iron. What kind of property - intensive or extensive - do you think

would be most useful in identifying the metal in the meteorite? Explain.

Intensive properties are unique to each substance so they are better for identifying. You can have 10 grams of just about

anything or 5 mL of of just about anything, but only iron has a density of exactly 7.78 g/mL

move for answer

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11 Which of the following would be an intensive physical property?

A The color of the liquid bromine is reddish brown

B The mass of the iron pipe is 25.67 grams

CThe aluminum block engine has a density of 2.7 g/mL

D Both A and B

E Both A and C

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12 Tungsten is a substance with an extremely high melting point and is used in light bulb filaments. Which of the following would be an extensive property of tungsten?

A Tungsten melts at 3422 C

B Tungsten has a silver color

C Tungsten has a specific heat of 0.134 J/gC

D A tungsten filament is 10 cm long

E A tungsten block will have a density of 15.6 g/mL

Slide 36 / 142

13 Of the following, only ________ is an extensive property.

A densityB massC boiling pointD freezing pointE temperature

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14 Which one of the following is not an intensive property?


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15 Which one of the following is an intensive property?


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Properties of Matter Summary

Physical Chemical

observed without changing identity of substance

observed by changing identity of substance

melting point, density, color, solubility, hardness, etc.

reactivity with other substances

Intensive Extensiveindependent of

sample sizedependent on sample size

color, melting point, density, etc.

mass, length, volume, etc.

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Classification of MatterEarlier in the unit, we discussed that matter was either a pure

substance or a mixture based on whether the composition was definite or variable.

Matter

MixturePure Substance

definite composition variable composition

Slide 41 / 142

Mixtures Mixtures are a combination of two or more substances that can vary in composition.

A classic example of a mixture would be salt water. Salt water can vary in it's "saltiness" which makes it a mixture and not a pure substance.

For example, the Mediterranean sea is roughly 5% more salty around Greece than it is off the coast of Spain.

Mixtures can be separated into pure substances by physical means such as heating. Desalinization factories heat salt water to evaporate the water and leave the salt behind.

Slide 42 / 142

Heterogeneous mixtures are different throughout. For instance, a raisin muffin, a chocolate chip cookie are

heterogeneous. But so is sand on the beach, since you can see differences in the sand due to grain size, etc.

Homogeneous mixtures are the same throughout. These are also called solutions. Tap water and the air you breathe

are excellent examples of solutions.

Types of Mixtures

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Solutions

The solvent is the substance present in the greatest abundance.

All other substances are solutes.

Solvent dissolves the solute.

Solutions are defined as homogeneous mixtures of two or more pure substances.

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Credit toTom Greebowe

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16 A combination of sand, salt, and water is an example of a __________.

A homogeneous mixtureB heterogeneous mixtureC compoundD pure substanceE solid

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17 If matter is uniform throughout and cannot be separated into other substances by physical processes, but can be decomposed into other substances by chemical processes, it is called a (an) _______.

A heterogeneous mixtureB elementC homogeneous mixtureD compoundE mixture of elements

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18 Homogeneous mixtures are also known as __________.

A solidsB compoundsC elementsD substancesE solutions

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Dissociation

When an ionic substance dissolves in water, the solvent pulls the individual ions from the crystal and solvates them.

This process is called dissociation .

_2+_

__

_

_

_

2+ _

_2+_

2+2+

2+

__

2+ _

_

2+

_ _

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Electrolytes and Nonelectrolytes

An electrolyte is a substances that dissociates into ions when dissolved in water.

A nonelectrolyte may dissolve in water, but it does not dissociate into ions when it does so.

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Soluble ionic compounds tend to be electrolytes.

Molecular compounds tend to be nonelectrolytes, except for acids and bases.

Electrolytes and Nonelectrolytes

Strong Weak Nonelectrolyte

Ionic All None None

Molecular strong acids weak acids All other weak bases compounds

electrolyte electrolyte

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Electrolytes

A strong electrolyte dissociates completely when dissolved in water.

A weak electrolyte only dissociates partially when dissolved in water.

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Electrolytes

Strong Electrolyte Weak Electrolyte Nonelectrolyte

HCl

HNO3

HClO4

H2SO4

NaOH

Ba(OH)2

Ionic Compounds

CH2COOH

HF

HNO2

NH3

H2O

(NH2)2CO (urea)

CH3OH (methanol)

C2H5OH (ethanol)

C6H12O6 (glucose)

C12H22O11 (sucrose)

The following are examples of chemicals that are strong and weak electrolytes. Nonelectrolytes do not dissociate in water.

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19 A strong electrolyte is one that _______ completely in solution.

A reactsB associatesC disappearsD ionizes(dissociates)E solidifies

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20 A weak electrolyte exists predominantly as __________ in solution.

A atomsB ionsC moleculesD electronsE an isotope

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21 Which of the following would make the most effective electrolyte when dissolved in water?

A CO2(g)

B NaCl(s)

C C6H12O6(s)

D C(s)

E N2(g)

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22 Which of the following would make the LEAST effective electrolyte when dissolved in water?

A C2H5OH(l)

B LiBr(s)

C NaNO3(s)

D MgCl2(s)

E All are effective electrolytes

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Solutions

The intermolecular forces between solute and solvent particles must be strong enough to compete with those between solute particles and those between solvent particles.

_2+_

_2+_

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How Does a Solution Form?As a solution forms, the solvent pulls solute particles

apart and surrounds, or solvates, them.

The solute is added to the solvent

The negative ions are pulled away by the positive pole of the solvent molecule

The positive ions are pulled away by the negative pole of the solvent molecule

-+

+-+

solventwater

solute

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If an ionic salt is soluble in water, it is because the ion-dipole interactions are strong enough to overcome the lattice energy of the salt crystal.

How Does a Solution Form?

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23 The process of solute particles being surrounded by solvent particles is known as _____.

A salutationB agglomerationC solvationD agglutinationE dehydration

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Energy Changes in Solution

∆H1- Separation of solute molecules

∆H2 - Separation of solvent molecules

+

∆H3- Formation of solute-solvent interactions

*

The heat content of a system includes the internal energy of a system and the pressure and temperature and is referred to as ∆H.

Three processes affect the energetics of solution:

· separation of solute particles

· separation of solvent particles

· new interactions between solute and solvent

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Energy Changes in Solution

The enthalpy change of the overall process depends on ∆H for each of these steps.

Solution can occur when the process is endothermic or exothermic. When heat is released or when it is pulled in from the surroundings.

Why?

Separated Separated solvent + solute particles particles

Separated Solvent + solute particles

Solvent + Solute

ΔH1

#H2

ΔH3

SolutionΔH solution

Net exothermic process

Ent

halp

y

*

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Gibbs Free Energy

Reactions, including solution, will occur spontaneously as long as the change in Gibbs Free Energy is negative.

When the process, is endothermic (heat is taken in from the surroundings), the increase in enthalpy is offset by an increase in entropy.

Separated Separated solvent + solute particles particles

Separated Solvent + solute particles

Solvent + Solute

ΔH1

ΔH2

ΔH3

SolutionΔH solution Net

endothermic process

*

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Just because a substance disappears when it comes in contact with a solvent, it doesn’t mean the substance dissolved.

Dissolution is a physical change — you can get back the original solute by evaporating the solvent.

If you can’t, the substance didn’t dissolve, it reacted.

Solutions

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Saturated Solutions

In a saturated solution, the solvent holds as much solute as is possible at that temperature.

Dissolved solute is in dynamic equilibrium with solid solute particles.

_+

_

_+

+ _

++__

++

_+

+_+_

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In an unsaturated solution, there is less solute dissolved in the solvent at that temperature.

Solid solute is not in dynamic equilibrium with dissolved solute

Unsaturated Solutions

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In supersaturated solutions, the solvent holds more solute than is normally possible at that temperature.

These solutions are unstable; crystallization can usually be stimulated by adding a “seed crystal” or scratching

the side of the flask.

Supersaturated Solutions

Click here for a video on Rapid Crystallization

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24 A saturated solution ________.

A contains as much solvent as it can hold

B contains no double bonds

C contains dissolved solute in equilibrium with undissolved solute

D will rapidly precipitate if a seed crystal is added

E cannot be attained

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25 An unsaturated solution is one that ______.

A has no double bonds

Bcontains the maximum amount of solute possible, and is in equilibrium with undissolved solute

C has less solute dissolved than the maximum solubility at that temperature

D contains more dissolved solute than the solubility allows

E contains no solute

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26 A solution with a concentration higher than the solubility is _____.

A is not possibleB is unsaturatedC is supercriticalD is saturatedE is supersaturated

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27 A supersaturated solution _________.

A is one with more than one soluteB is one that has been heated

C is one with more amount of solute than its solubility

D must be in contact with undissolved solids

E exists only in theory and cannot actually be prepared

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Factors Affecting SolubilityChemists use the axiom “like dissolves like."

Alcohol Solubity in water

Solubility in hexane

CH3OH methanol

# 0.12

CH3CH2OHethanol

# #

CH3CH2CH2OHpropanol

# #

CH3CH2CH2CH2OHbutanol 0.11 #

CH3CH2CH2CH2CH2OHpentanol 0.030 #

CH3CH2CH2CH2CH2CH2OH hexanol 0.0058 #

solubility expressed in mol/100g solvent# = completely miscible

Polar substances tend to dissolve in polar solvents.

Nonpolar substances tend to dissolve in nonpolar solvents.

http://njc.tl/n0

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Factors Affecting Solubility

Hydrogenbonding sites

Glucose- has hydroxyl groups

and is highly soluble in water

Cyclobutane-has no polar OH groupsand is essentially insoluble in water

The more similar the intermolecular attractions, the more likely one substance is to be soluble in another. Glucose (which has hydrogen bonding) is very soluble in water, while cyclobutane (which only has dispersion forces) is not.

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Factors Affecting Solubility

Vitamin CVitamin A

soluble in nonpolar compounds (like fats)

soluble in water

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28 The phrase "like dissolves like" refers to the fact that _________.

A gases can only dissolve other gases

Bpolar solvents dissolve polar solutes; nonpolar solvents dissolve nonpolar solutes

C solvents can only dissolve solutes of similar molar mass

D condensed phases can only dissolve other condensed phases

E polar solvents dissolve nonpolar solutes and vice versa

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29 Which one of the following is most soluble in water?

A CH3OHB CH3CH2CH2OHC CH3CH2OHD CH3CH2CH2CH2OHE CH3CH2CH2CH2CH2OH

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30 Which one of the following is most soluble in hexane (C6H14 )?

A CH3OHB CH3CH2CH2OHC CH3CH2OHD CH3CH2CH2CH2OHE CH3CH2CH2CH2CH2OH

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31 Which of the following substances is more likely to dissolve in CH 3OH?

A CCl4B KrC N2

D CH3CH2OHE H2

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32 Which of the following substances is more likely to dissolve in water?

A HOCH2CH2OH

B CHCl3

C CH3(CH2)9 HCO

D CH3(CH2)8CH2OH

E CCl4

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33 Which one of the following substances is more likely to dissolve in CCl 4?

A CBr4

B HBrC HClD CH3CH2OHE NaCl

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Temperature and Solubility

A solubility chart can be used to determine the amount of solute that can be dissolved by a particular solvent at a range of temperatures. The line of a solubility chart represents a saturated solution. A point above the line represents a supersaturated solution at that temperature.

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A point above the line represents a supersaturated

solution at a specific temperature.

The line of a solubility chart

represents a saturated solution.

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34 The point on the graph represents a solution that is:

A Unsaturated

B Saturated

C Supersaturated

D Cannot be Determined

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A Unsaturated

B Saturated

C Supersaturated


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A Unsaturated

B Saturated

C Supersaturated


Slide 86 / 142


A Unsaturated

B Saturated

C Supersaturated


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A Unsaturated

B Saturated

C Supersaturated


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A Unsaturated

B Saturated

C Supersaturated


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40 The change in concentration show on the graph below is most likely due to (assume there is no phase change and the amount of water remains constant)

A More solute being added to the solution at constant temperature

B No extra solute added and the solution being cooled

C The solution heated, more solute added, then the solution is cooled

D None of the above

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41 The change in concentration show on the graph below is most likely due to (assume there is no phase change and the amount of water remains constant)




D None of the above

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42 The change in concentration shown on the graph below is most likely due to (assume there is no phase change and the amount of water remains constant)




D None of the above

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Generally, the solubility of solid solutes in liquid solvents increases with increasing temperature.


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The opposite is true of gases.

Carbonated soft drinks are more “bubbly” if stored in the refrigerator.

Warm lakes have less O2 dissolved in them than cool lakes.

Temperature and Solubility of gases

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The solubility of liquids and solids does not change appreciably with pressure. The solubility of a gas in a liquid is directly proportional to its pressure.

Gases in Solution

In general, the solubility of gases in water increases with increasing molar mass. Larger molecules have stronger dispersion forces.

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43 Increasing the temperature _____ the solubility of solids and ______ the solubility of gases in a liquid.

A decreases, increasesB doesn't affect, increasesC increases, decreasesD increases, increasesE doesn't affect, doesn't affect

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44 Increasing the pressure on a liquid _____ the solubility of solids and ______ the solubility of gases in a liquid.

A decreases, increasesB doesn't affect, increasesC increases, decreasesD increases, increasesE doesn't affect, doesn't affect

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45 Pressure has an appreciable effect on the solubility of __________ in liquids.

A gasesB solidsC liquidsD saltsE solids and liquids

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Recall that solutions are homogeneous mixtures of two or more pure substances. In a solution, the solute is dispersed uniformly

throughout the solvent.

Expressing Concentrations of Solutions

State of Solution

State of Solvent State of Solute Example

Gas Gas Gas Air

Liquid Liquid Gas Oxygen in water

Liquid Liquid Liquid Alcohol in water

Liquid Liquid Liquid Salt in water

Solid Solid Gas H2 in Palladium

Solid Solid Liquid Hg in Silver

Solid Solid Solid Silver in Gold

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Mass Percentage of solute

mass of A in solutiontotal mass of solutionMass % of solute A = x 100%

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46 The concentration of urea in a solution prepared by dissolving 16 g of urea in 39 g of H2O is ______% by mass.

A 29B 41C 0.29D 0.41E 0.48

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47 A solution contains 11% by mass of sodium chloride. This means that ______.

A there are 11 g of sodium chloride in in 1.0 mL of this solution

B 100 g of the solution contains 11 g of sodium chloride

C 100 mL of the solution contains 11 g of sodium chloride

D the density of the solution is 11 g/mL

E the molality of the solution is 11

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moles of Atotal moles (A+B) in solutionXA =

Mole Fraction (X)

In some applications, one needs the mole fraction of solvent, not solute — make sure you find the quantity you need!

Assume a solute A is dissolved in a solvent B

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48 What is the mole fraction of Nitrogen in a mixture of gas containing 5 moles of Nitrogen and 15 moles of Oxygen.

A 0.25

B 4

C 3

D 0.75

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49 The mole fraction of He in a gaseous solution prepared from 4.0 g of He, 6.5 g of Ar, and 10.0 g of Ne is ______.

A 0.60B 1.5C 0.20D 0.11E 0.86

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50 The mole fraction of urea (MW = 60.0 g/mol) in a solution prepared by dissolving 16 g of urea in 39 g of H2O is _______.

A 0.58B 0.37C 0.13D 0.11E 9.1

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Molarity (M)

Two solutions can contain the same compounds but be quite different because the proportions of those compounds are different.

Molarity is one way to measure the concentration of a solution.Since volume is temperature-dependent, molarity can change with temperature.

moles of the solutevolume of solution in liters

Molarity (M) =

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51 When 0.500 mol of HC2H3O2 is combined with enough water to make a 300.0 mL solution, the concentration of HC2H3O2 is ____ M. A 3.33B 1.67C 0.835D 0.00167E 0.150

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52 What is the concentration (M) of CH3OH in a solution prepared by dissolving 11.7 g of CH 3OH in sufficient water to give exactly 230 mL of solution?

A 11.9B 1.59 x 10-3

C 0.0841D 1.59E 11.9 x 10-3

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mol of solutekg of solventm =

Molality (m)

Since both moles and mass do not change with temperature, molality (unlike molarity) is not temperature-dependent.

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53 The concentration of a benzene solution prepared by mixing 12.0 g C6H6 with 38.0 g CCl 4 is __________ molal.

A 4.04B 0.240C 0.622D 0.316E 0.508

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54 The concentration of HCl in a solution that is prepared by dissolving 5.5 g of HCl in 200g of C2H6O is __________ molal.

A 27.5B 7.5 x 10-4

C 3.3 x 10-2

D 0.75E 1.3

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55 Which one of the following concentration units varies with temperature?

A molalityB mass percentC mole fractionD molarityE all of the above

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56 Which one of the following is a correct expression for molarity?

A mol solute/L solventB mol solute/mL solventC mmol solute/mL solutionD mol solute/kg solventE μmol solute/L solution

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Colligative Properties

Colligative properties depend only on the number of solute particles present, not on the identity of the solute particles.

Among colligative properties are:

Vapor pressure lowering Boiling point elevation

Melting point depressionOsmotic pressure

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Vapor Pressure Lowering

Because of solute-solvent intermolecular attraction, higher concentrations of nonvolatile solutes make it harder for solvent to escape to the vapor phase.

Therefore, the vapor pressure of a solution is lower than that of the pure solvent. Solvent alone Solvent + Solute

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Boiling Point Elevation and Freezing Point Depression

Nonvolatile solute-solvent interactions also cause solutions to have higher boiling points and lower freezing points than the pure solvent.

The Boiling point elevation and freezing point depression depend on the number solute particles in the solution( colligative property)

TMP TBPSolution SolutionSolvent

Pre

ssur

e

Temperature

1 atm

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Colligative Properties and Ionization

We said earlier that colligative properties depend only on the number of solute particles present , not on the identity of the solute particles.

However, it's important to note that it's the number of particles in solution, not the number of particles before they are dissolved.

If a solute ionizes, you can get more particles in solution than you started with...depending on the substance.

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For instance,

1 mol NaCl becomes 2 moles of particles in solution: 1 mol Na+ + 1 mol Cl-

1 mol CaCl2 becomes 3 moles in solution: 1 mol Ca+ + 2 mol Cl-

1 mol C6H12O6 (glucose) stays 1 mol since it doesn't disassociate, it's stays a single molecule because it is a molecular compound.

So in terms of colligative properties; you get about three times the effect with CaCl2 (and two times the effect with NaCl) than you do with C6H6.

Colligative Properties and Ionization

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57 Which of the following will have the highest boiling point?

B 0.10 m aqueous glucose C 0.20 m aqueous sucrose ( table sugar)

A pure H2O

E 0.20 m NaCl D 0.20 m CaCl2

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58 Which of the following will have the lowest freezing point?

B 0.20 M Pb(NO3)2 C 0.20 M KOH

A 0.10 m aqueous sucrose (C 12 H22 O11)

E 0.20 M KClD 0.20 M NaNO3

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59 Which of the following will have the lowest vapor pressure?

B 0.20 M Pb(NO3)2 C 0.20 M AlCl3

A pure H2O

E 0.20 M MgF2

D 0.20 M SrCl2

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60 Which of the following aqueous solutions will have the lowest vapor pressure?

A 0.25 M glucose, C6H12O6

B 0.50 M glucose

C 0.50 sucrose, C12H22O11

D 1.0 M sucrose

E All of these aqueous solutions have equal vapor pressure.

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61 Which of the following aqueous solutions will have the highest vapor pressure?

A 0.75 M glucose, C6H12O6

B 0.50 M glucose

C 0.25 M sucrose, C12H22O11

D 0.50 M sucrose

E All of these aqueous solutions have equal vapor pressure.

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62 Which of the following will have the highest vapor pressure?

A pure water

B 1.0 m sucrose (aq)

C 1.0-m NaCl (aq)

D 1.0-m HCl (aq)

E 1.0-m CaCl2 (aq)

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63 Which of the following will have the lowest vapor pressure?

A pure water


C 1.0-m CaCl2 (aq)

D 1.0-m HCl (aq)

E 1.0-m KCl (aq)

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64 Which of the following will have the highest boiling point?

A pure water


C 1.0-m NaCl (aq)

D 1.0-m HCl (aq)

E 1.0-m CaCl2 (aq)

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65 Which of the following will have the lowest boiling point?

A pure water


C 1.0-m NaCl (aq)

D 1.0-m HCl (aq)

E 1.0-m CaCl2 (aq)

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66 Which of the following will have the highest freezing point?

A pure water

B 0.20-m glucose (aq)

C 0.20-m KBr (aq)

D 0.20-m HCl (aq)

E 0.20-m AlCl3 (aq)

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67 Which of the following will have the lowest freezing point?

A pure water

B 0.15-m Mg(NO3)2 (aq)

C 0.15-m glucose(aq)

D 0.15-m NaF (aq)

E 0.15-m HBr (aq)

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68 Which of the following aqueous solutions will have the highest boiling point? A 0.10 m NaClB 0.15 m NaClC 0.20 m NaClD 0.25 m NaClE pure water

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69 As the concentration of a solute in a solution increases, the freezing point of the solution ______ and the vapor pressure of the solution ______.

A increases, increasesB increases, decreasesC decreases, increasesD unaffected, decreasesE decreases, decreases

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70 Which of the following solutions will have the lowest freezing point?

A pure H2OB 0.10 m aqueous glucoseC 0.15 m aqueous glucoseD 0.20 m aqueous glucoseE 0.25 m aqueous glucose

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71 Colligative properties of solutions include all of the following except __________.

A depression of vapor pressure upon addition of a solute to a solvent

Belevation of the boiling point of a solution upon addition of a solute to a solvent

Cdepression of the freezing point of a solution upon addition of a solute to a solvent

Dan increase in the osmotic pressure of a solution upon the addition of more solute

E the increase of reaction rates with increase in temperature

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Credit to Tom Greenbowe

Colligative properties

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Osmosis

Some substances form semipermeable membranes, allowing some smaller particles to pass through, but blocking other larger particles.

In biological systems, most semipermeable membranes allow water to pass through, but solutes are not free to do so.

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In osmosis, there is net movement of solvent from the area of higher solvent concentration (lower solute concentration ) to the area of lower solvent concentration (higher solute concentration ).

Osmosis

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Osmotic PressureThe pressure required to stop osmosis, known as

osmotic pressure , P is

PV = nRT

P = nRT/V = MRTwhere M is the molarity of the solution.

If the osmotic pressure is the same on both sides of a membrane (i.e., the concentrations are the same), the solutions are isotonic.

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Osmosis in Cells

If the solute concentration outside the cell is greater than that inside the cell, the solution is hypertonic .

Water will flow out of the cell, and crenation results.

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Osmosis in Cells

If the solute concentration outside the cell is less than that inside the cell, the solution is hypotonic .

Water will flow into the cell, and hemolysis results.

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72 Osmosis is best defined as the movement of:

A Molecules from an area of high concentration to an area of lower concentration

B Molecules from an area of low concentration to an area of higher concentration

C Water molecules across a membrane from an area of low water to an area of higher concentration

D Water molecules across a membrane from an area of high concentration to low area of concentration

E Water molecules inside a container

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73 Which of the following will pass through a cell membrane most easily?

A small polar moleculesB small nonpolar moleculesC large polar moleculesD large nonpolar moleculesE large neutral molecules

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properties of matter and solutions

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