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 Notation

A 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 10

3.2 10

x

x

Uncertainty in MeasurementsExact numbers – defined values

Conversion factors Date Time Counting small number of objects

Inexact numbers – uncertainty in numbers All measurements

Limits of Measurements

Precision- 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 lb

Temp Celsius °C Fahrenheit °F

Time second s second s

Prefixes for Metric Units

Prefix Symbol MeaningMultiply 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 Analysis

Conversion 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 Analysis

Problem: 26.5 inches equals how many centimeters?

Dimensional Analysis

Problem: How many seconds are in one day?

Dimensional Analysis

Problem: Your car has a 5.00 liter engine. What is the size of this engine in cubic inches?

Temperatures

Temperature 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

Temperature

What is 65.3 °F in °C?

What is 56 °C in K?

Density

Which 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.

Density

What is the density of a metal rod that weighs 55.64 grams and has a volume of 34 ml?

Density

What 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.

Density

What 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

Density

A 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?