chemistry
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Chemistry. Chapter 1- Matter and Measurement. What is Chemistry?. Chemistry is the science concerned with the composition, structure, and properties of matter. Matter. Physical material of the universe; it is anything that has mass and occupies space. Classified by: Physical State Gas - PowerPoint PPT PresentationTRANSCRIPT
Chemistry
Chapter 1- Matter and Measurement
What is Chemistry?
Chemistry is the science concerned with the composition, structure, and properties of matter.
Matter Physical material of the universe; it is
anything that has mass and occupies space.Classified by: Physical State
Gas Liquid Solid ?????
Composition
Composition Heterogeneous – visually distinctive parts -
a mixture that is not uniform in composition, properties, and appearance throughout.
Homogeneous – mixtures that are uniform throughout.
Mixture (solution)- matter that is uniform throughout and can be separated.
Pure substance - matter that has distinct properties and composition that does not vary from sample to sample and can not be separated.
Element – simplest form of matter Compound – composed of two or more elements
Matter
Uniform distribution?
Heterogeneous Mixture
Fixed composition
Pure substance
Can it be broken down intoSimpler substances?
element
Homogenous
Solution/mixture
compound
NO YES
NOYES
NO YES
Properties Physical Properties – can be measured without
changing the identity and composition of the substance.
Chemical Properties - describes the way a substance may change or react to form other substances.
Intensive Properties – not dependent on amount of substance and used for identification.
Extensive Properties – depend on amount of the substance.
Chemical/Physical Changes Physical changes – changes in the
physical appearance of a substance. Chemical changes – changes in the
substance such that it forms a new substance.
Formation of a light Formation of a gas Formation of a precipitate Change in temperature Permanent change in color
Scientific NotationA method of expressing a number as a product of a number between 1 and 10 and the appropriate power of 10.
Ex. 9400 in scientific notation is 9.4 x 103
0.0000943 in scientific notation is
9.43 x 10-5
Multiplication of Scientific Notation
Ex. (4.6 x 105) x ( 3.2 x 103)
1. Multiply the numbers2. Add the exponents3. Rewrite in correct notation
(4.6 x 3.2) x 10(5+3)
=14.72 x 108
=1.472 x 109
Division of Scientific Notation
Ex. (4.6 x 105) ÷ ( 3.2 x 103) =
1. Divide the numbers2. Subtract the exponents3. Rewrite in correct notation
(4.6 / 3.2) x 10(5-3) = 1.437 x 102
5
3
4.6 103.2 10xx
Uncertainty in MeasurementsExact numbers – defined values
Conversion factors Date Time Counting small number of objects
Inexact numbers – uncertainty in numbers All measurements
Limits of MeasurementsPrecision- is a measure of how closely
individual measurements agree with one another.
Accuracy- refers to how closely individual measurements agree with the correct value.
Significant figures –all numbers recorded in a measurement with all numbers certain plus 1 uncertain number (the last number)
Precision vs. Accuracy
1. The only numbers that can be non-significant
are zeros.
2. Any zero at the beginning of a number is not significant. It serves only to locate the decimal.
3. Any zero on the right hand end of a number is only significant if followed by a decimal or on the end of a decimal number.
4. Any zero between numbers is significant.
5. Exact numbers are significant.
Rules for Significant Figures
• Mass of an eyelash is 0.000304
•Length of a skid mark is 123.0
•125 gram sample of chocolate chip cookies contains 10 grams of chocolate
•The volume of soda remaining in a can after a spill is 0.09020 liters
•A dose of antibiotic is 0.040 cm3
Example
Adding and Subtracting Numbers Scientifically
When you add or subtract numbers, you can have no more decimal places in the answer than the fewest decimal places in the numbers that are added or subtracted.
Ex. 1.345 + .27 = 13.90 – 4.8122 = 134.1890 + 72.1 = 0.00459 + 0.0023 =
Multiplying and Dividing
When multiplying or dividing. You can have no more significant figures in the answer than the fewest number of significant figures in any number used to multiply or divide.
Ex. 45.34 ÷ 17.1 = (11.01)(34.2)/12.34= (45.0)/(45.689)=
Units Measurements English system SI units – International System of Units
or Metric system
Measurement SI Symbol English Symbol
Length meter m yard yard
Volume liter L Gallon gal
Mass gram g pound lbTemp Celsius °C Fahrenheit °FTime second s second s
Prefixes for Metric UnitsPrefix Symbol Meaning
Multiply unit by…
Example meter
giga G billion (109) 1,000,000,000 Gm
mega M Million (106) 1,000,000 Mm
kilo KThousand (103) 1,000 Km
Base 1 meter
deci d Tenth (10-1) 0.1 dm
centi cHundredth (10-2) 0.01 cm
milli mThousandth (10-3) 0.001 mm
micro μ Millionth (10-6) 0.000001 μ m
Ex. 1 meter (m) = 1000 millimeters (mm)
1 meter (m) = 100 centimeters (cm)1000 meters = 1 Kilometer (km)
1000 grams (g) = 1 kilogram (kg)
1 liter (l) = 1000 milliliters (ml)1000 milliliters = 1 liter
Dimensional AnalysisConversion Factors -ratio of equivalent
measurements to convert from one unit to another.
Ex. 1 meter = 100 centimeters1 inch = 2.54 centimeters1 gallon = 4 quarts1 meter = 1.0936 yards
Using Dimensional Analysis
Problem- How many meters in 3.4 cm?3.4 cm = ? m
Need a conversion factor between cm and m
3.4 cm x cf = ? m
Dimensional AnalysisProblem: 26.5 inches equals how many
centimeters?
Dimensional AnalysisProblem: How many seconds are in one
day?
Dimensional AnalysisProblem: Your car has a 5.00 liter engine.
What is the size of this engine in cubic inches?
TemperaturesTemperature can be measured in °F, °C, and KK=the absolute or Kelvin scale
Water freezes at 0°C, 32 °F, and 273 K
Water boils at 100°C, 212 °F, and 373 K
°C = 5/9 (°F - 32.0)°F = 9/5 (°C) + 32.0
K = °C + 273
TemperatureWhat is 65.3 °F in °C?
What is 56 °C in K?
DensityWhich is heavier a pound of lead or
a pound of feathers?
Weight = mass = pounds
Density = mass/volume
So one needs larger volume of feathers to make a pound than lead.
Density
The amount of matter in a given volume of a substance.
DensityWhat is the density of a metal rod that
weighs 55.64 grams and has a volume of 34 ml?
DensityWhat is the density of a metal medallion
that weighs 13 grams? How do you find volume?
Water Displacement Method Used to determine the
volume of an irregular shaped object.
DensityWhat is the volume of a metal medallion
with a density of 34. 7 g/ml that weighs 2.5 g ?
Select an equation to solve for a different unknown.
d = m/v Solve for density
m = dv Solve for mass
v = m/d Solve for volume
DensityA block of metal is 3.45 cm by 2.78 cm by
7.98 cm. If this block of metal weighs 612.0 g, what is the density of the metal?