Chapter 1Matter and Measurement

Chm 108Suroviec Fall 2014

Chemistry is concerned with matter and energy and how the two interact with each other

Chemistry is a foundation for other disciplines Engineering – polymers, energy, pharmaceuticals

Health sciences Pharmacy and pharmacology Scientific writing

Chemistry

I. Atoms and Molecules3

Air is made of several components

Atoms are particles that constitute the fundamental building block of matter

Molecules are 2 or more molecules joined together

I. Atoms and Molecules4

Properties of various substances depend on the molecules and atoms that make them up

H2O vs H2O2

II. Classification of Matter

Matter has mass Not the same as weight

Matter occupies space

Phases of matter Solids

Fixed volume and shape

Liquids Fixed volume, indefinite shape

Gases Indefinite shape and volume

B. Elements/Compounds/Mixtures6

Besides classifying by state also classify by composition

Starting with all matter ask does the composition vary if you took 2 samples

Pure substance

Mixtures

Classification of Matter

III. Physical and Chemical Changes

8

We are constantly seeing changes in matter: Evaporate, rust, rotting, freezing, etc

But what happens to the molecules during these changes?

II. Physical and Chemical Changes

physical change: does not alter the composition or identity of a substance.

chemical change: alters the composition or identity of the substance(s) involved.

01_07.JPG

IV. Units of Measurements11

In 1999 the US and European scientists working together on the Mars Climate Orbiter realized after they had all ready sent the satellite off that half of the measurements were in metric and half in English. The satellite was lost.

Table 1.2 - Powers of Ten

Table 1.3 – Units and Unit Relations

IV. Units of Measurements14

A. Meter and Length B. Kilogram and Mass

IV. Units of Measurement15

C. Time and seconds D. Temperature and Kelvin

E. Volume and Density16

Volume is measurement of space and length3

Density Ratio of mass to volume

V. Reliability of Measurement17

If we were to measure water using a beaker an then again with a graduated cylinder:

Scientific measurements are reported so that every digit is certain except the last

This digit is an estimate

V. Reliability of Measurements

Significant Figures Every measurement carries uncertainty All measurements must include estimates of uncertainty with them

There is an uncertainty of at least one unit in the last digit

Significant figures are meaningful digits in measurements In 8.00 mL, there are three significant figures In 8.0 mL, there are two significant figures In 8 mL, there is one significant figure

A. Scientific Notation

The number of atoms in 12 g of carbon:

602,200,000,000,000,000,000,000

6.022 x 1023

The mass of a single carbon atom in grams:

0.0000000000000000000000199

1.99 x 10-23

N x 10nN is a number between 1 and 10

n is a positive or negative integer

A. Scientific Notation

Convert the following to scientific notation:

0.000 000 000 372 m (diameter of Na atom)

150,000,000m (distance from Earth to moon)

Accuracy – how close a measurement is to the true value

Precision – how close a set of measurements are to each other

accurate&

precise

precisebut

not accurate

not accurate&

not precise

B. Precision and Accuracy

VI. Unit Conversion

In many cases throughout your study of chemistry, the units (dimensions) will guide you to the solution of a problem

Always be sure your answer is reported with both a number and a set of units!

VI. Unit Conversions

Conversion factors are used to convert one set of units to another Only the units change Conversion factors are numerically equal to 1 1L = 1000 cm3

1cm1000

cm1000

cm1000

L13

3

3

VI. Unit Conversion

Conversion Unit 1 x 1012pg = 1 g

Convert 1.00 mg into picograms

How large is Australia in sq meters if 1 mile = 1609.34 metersand the land mass = 2,941,526 sq. miles?

How much does a person weigh in pounds if they weigh 11.29stone, given that 1 stone = 14 pounds. Use significant figures.

A. Problems with Equations25

With these problems you are going to find one of the variables given the rest.

Find the radius in cm of a water droplet with a volume of 0.06cm2 using V = (4/3)r2