solutions
DESCRIPTION
Solutions. Solutions. Definition: Homogeneous mixture of two or more substances in a single phase. Like Dissolves Like (i.e. nonpolar molecules dissolve in nonpolar molecules) Solid mixtures: alloys (brass, sterling silver) Liquid mixtures: alcohol & water Gas mixtures: air. Other Terms. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/1.jpg)
Solutions
![Page 2: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/2.jpg)
Solutions
Definition: Homogeneous mixture of two or more substances in a single phase.
Like Dissolves Like (i.e. nonpolar molecules dissolve in nonpolar molecules) Solid mixtures: alloys (brass, sterling silver) Liquid mixtures: alcohol & water Gas mixtures: air
![Page 3: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/3.jpg)
Other Terms
Soluble: capable of dissolving Insoluble: incapable of dissolving Miscible: 2 liquids dissolve into each other Immiscible: 2 liquids do not dissolve into
each other Solubility: how much of a given solute a
certain solvent can dissolve at a certain temperature & pressure
![Page 4: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/4.jpg)
Components of Solutions
Solute: is dissolved by the solvent. Found in lesser quantities May be electrolytes (conduct electricity) or non-
electrolytes (does not conduct electricity) Solvent: does the dissolving
Water is the universal solvent http://www.dlt.ncssm.edu/TIGER/chem2.htm#sto
ich
![Page 5: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/5.jpg)
Rates of Dissolving
Rate of dissolving may speed up due to the following:
1. Increased Surface Area: breaking the solute up into smaller pieces
2. Increased Stirring: increases particle collisions
3. Heating: particles move faster = more collisions.
![Page 6: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/6.jpg)
Solubility
Varies with temperature Solids & Liquids: Temp ↑, solubility ↑ Gases: Temp ↑, solubility ↓
Henry’s Law: Solubility of a gas in liquid is directly proportional to pressure
![Page 7: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/7.jpg)
Solubility
Saturated: The maximum amount of a solute that can be dissolved into a solvent.
Unsaturated: less than the maximum amount of solute that can be dissolved.
Supersaturated: More dissolved solute than a saturated solution at the same temperature Must be heated, then cooled slowly Very unstable
![Page 8: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/8.jpg)
Solubility Curve
The lines represent the different saturation points for different compounds
Notice, the solubilities are measured in g/100 g H2O
Under the line is unsaturated, over the line is supersaturated
![Page 9: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/9.jpg)
Solution Concentration
The concentration of a solution is measured in Molarity (M)
M = moles / liter M = mol/L
(moles of solute per liters of solution)
Diluting solutions: M1V1 = M2V2
![Page 10: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/10.jpg)
Practice Problems
You have 3.50 L of solution that contains 90.0 g of NaCl. What is the molarity of this solution? Answer: 0.44 M
You have 0.8 L of a 0.5 M HCl solution. How many moles of HCl are present?
Answer: 0.4 mol HCl What volume of 3.00 M NaCl is needed for a
reaction that requires 146.3 g of NaCl? Answer: 0.834 L
![Page 11: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/11.jpg)
Dilutions Practice Problems
You want to make 2.3 L of a 3.5 M H2SO4 solution. If you only have 12 M sulfuric acid in stock, how much must be added to water to make the solution you need?
Answer: In lab you produce 2.5 L of 6 M HNO3. If you
added 0.5 L of a concentrated solution to get this solution, what was the original concentration of the acid?
![Page 12: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/12.jpg)
Molality:
Another way to measure concentration. Moles of solute per kilogram of solvent
m = mol / kg Notice: solvent must be in kg! Example: A solution was prepared by
dissolving 17.1 g of sucrose (C12H22O11) in 125 g of water. Find the molal concentration.
Answer: 0.400 m
![Page 13: Solutions](https://reader036.vdocuments.us/reader036/viewer/2022062301/5681501f550346895dbe0427/html5/thumbnails/13.jpg)
Molality Examples
A solution of I2 in CCl4 is used when iodine is needed for certain chemical tests. How much iodine must be aded to prepare a 0.480 m solution of iodine in CCl4 if 100.0 g of CCl4 is used?
Answer: 12.2 g of I2
What is the molality of a solution composed of 255 g (CH3)2CO dissolved in 200. g of water?
Answer: 22 m