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Introduction Matter and Measurement

Chapter 1

The Study of Chemistry

What is chemistry?

- Chemistry is the study of the properties and

behavior of matter. - Matter anything that occupies space and has

mass.

Classification of Matter

- States of Matter

Classification of Matter

- States of Matter

Gas

Liquid

Solid

Classification of Matter

- States of Matter

Shape Volume

Gas

Liquid

Solid

Classification of Matter

States of Matter

Shape Volume

Gas indefinite

Liquid

Solid

Classification of Matter

States of Matter

Shape Volume

Gas indefinite indefinite

Liquid

Solid

Classification of Matter

States of Matter

Shape Volume

Gas indefinite indefinite

Liquid indefinite

Solid

Classification of Matter

States of Matter

Shape Volume

Gas indefinite indefinite

Liquid indefinite definite

Solid

Classification of Matter

States of Matter

Shape Volume

Gas indefinite indefinite

Liquid indefinite definite

Solid definite

Classification of Matter

States of Matter

Shape Volume

Gas indefinite indefinite

Liquid indefinite definite

Solid definite definite

Classification of Matter

- The basic difference between these states is the

distance between the bodies. - Gas bodies are far apart and in rapid motion.
- Liquid bodies closer together, but still able

to move past each other. - Solid bodies are closer still and are now held

in place in a definite arrangement.

Classification of Matter

Classification of Matter

Pure Substances and Mixtures

- Mixture combination of two or more substances

in which each substance retains its own chemical

identity. - Homogeneous mixture composition of this mixture

is consistent throughout. - Heterogeneous mixture composition of this

mixture varies throughout the mixture.

Classification of Matter

Pure Substances and Mixtures

- It is also possible for a homogeneous substance

to be composed of a single substance pure

substance. - Element A substance that can not be separated

into simpler substances by chemical means. - Compound A substance composed of two or more

elements united chemically in definite

proportions.

Classification of Matter

Pure Substances and Mixtures

- The smallest unit of an element is an atom.
- Atom the smallest unit of an element that

retains a substances chemical activity.

Classification of Matter

Separation of Mixtures

- Mixtures can be separated by physical means.
- Filtration.
- Chromatography.
- Distillation.

Classification of Matter

Separation of Mixtures

Classification of Matter

Elements

- There are 114 elements known.
- Each element is given a unique chemical symbol

(one or two letters). - Carbon C, nitrogen N, titanium Ti.
- Notice that the two letter symbols are always

capital letter then lower case letter because - CO carbon and oxygen.
- Co element cobalt.

Classification of Matter

Compounds

- Formed by combining elements.
- The proportions of elements in compounds are the

same irrespective of how the compound was formed. - Law of Constant Composition (or Law of Definite

Proportions) - The composition of a pure compound is always the

same, regardless of its source.

Properties of Matter

Physical and Chemical Changes

- Physical Property (Change) A property that can

be measured without changing the identity of the

substance. - Example melting point, boiling point, color,

odor, density - Physical changes do not result in a change of

composition.

Properties of Matter

Physical and Chemical Changes

- Intensive properties independent of sample

size. - Extensive properties - depends on the quantity

of the sample.

Properties of Matter

Physical and Chemical Changes

- Chemical change (chemical reaction) the

transformation of a substance into a chemically

different substance. - When pure hydrogen and pure oxygen react

completely, they form pure water.

Scientific Method

Scientific Method

Hypothesis tentative explanation based on a

limited number of observations. Scientific law

A concise verbal or mathematical equation that

summarizes a broad variety of observations and

experiences. Theory an explanation of the

general principles of certain phenomena with

considerable evidence or facts to support it.

Units of Measurement

SI Units

- There are two types of units
- fundamental (or base) units
- derived units.
- There are 7 base units in the SI system.
- Derived units are obtained from the 7 base SI

units.

Units of Measurement

SI Units

- There are two types of units
- fundamental (or base) units
- derived units.
- There are 7 base units in the SI system.
- Derived units are obtained from the 7 base SI

units. - Example

Units of Measurement

SI Units

Units of Measurement

SI Units

Units of Measurement

Mass

- Mass is the measure of the amount of material in

an object. - This is not the same as weight which is dependant

on gravity.

Units of Measurement

Temperature

Units of Measurement

Temperature

Kelvin Scale Used in science. Same temperature

increment as Celsius scale. Lowest temperature

possible (absolute zero) is zero Kelvin.

Absolute zero 0 K -273.15oC. Celsius

Scale Also used in science. Water freezes at 0oC

and boils at 100oC. To convert K oC

273.15. Fahrenheit Scale Not generally used in

science. Water freezes at 32oF and boils at

212oF.

Units of Measurement

Temperature

Converting between Celsius and Fahrenheit

Units of Measurement

Volume

- The units for volume are given by (units of

length)3. - i.e., SI unit for volume is 1 m3.
- A more common volume unit is the liter (L)
- 1 L 1 dm3 1000 cm3 1000 mL.
- We usually use 1 mL 1 cm3.

Units of Measurement

Density

Density mass per unit volume of an object.

Uncertainty in Measurement

- All scientific measures are subject to error.
- These errors are reflected in the number of

figures reported for the measurement. - These errors are also reflected in the

observation that two successive measures of the

same quantity are different.

Uncertainty in Measurement

Precision and Accuracy

- Measurements that are close to the correct

value are accurate. - Measurements which are close to each other are

precise. - Measurements can be
- accurate and precise
- precise but inaccurate
- neither accurate nor precise

Uncertainty in Measurement

Precision and Accuracy

Uncertainty in Measurement

Significant Figures

- The number of digits reported in a measurement

reflect the accuracy of the measurement and the

precision of the measuring device. - All the figures known with certainty plus one

extra figure are called significant figures. - In any calculation, the results are reported to

the fewest significant figures (for

multiplication and division) or fewest decimal

places (addition and subtraction).

Uncertainty in Measurement

Significant Figures

- Non-zero numbers are always significant.
- Zeros between non-zero numbers are always

significant. - Zeros before the first non-zero digit are not

significant. Zeros at the end of the number after

a decimal place are significant. - Zeros at the end of a number before a decimal

place are ambiguous. For this course we will

consider these to be significant. - Example so for this class, the number 10,300

has 5 significant figures.

Uncertainty in Measurement

Significant Figures

- Multiplication / Division
- The result must have the same number of

significant figures as the least accurately

determined data - Example
- 12.512 (5 sig. fig.)
- 5.1 (2 sig. fig.)
- 12.512 x 5.1 64
- Answer has only 2 significant figures

Uncertainty in Measurement

Significant Figures

- Addition / Subtraction.
- The result must have the same number of digits to

the right of the decimal point as the least

accurately determined data. - Example
- 15.152 (5 sig. fig., 3 digits to the right),
- 1.76 (3 sig. fig., 2 digits to the right),
- 7.1 (2 sig. fig., 1 digit to the right).
- 15.152 1.76 7.1 24.0
- 24.0 (3 sig. fig., but only 1 digit to the right

of the decimal point)

Uncertainty in Measurement

Rounding rules

- If the leftmost digit to be removed is less than

5, the preceding number is left unchanged. Round

down. - If the leftmost digit to be removed is 5 or

greater, the preceding number is increased by

1. Round up.

Dimensional Analysis

- In dimensional analysis always ask three

questions - What data are we given?
- What quantity do we need?
- What conversion factors are available to take us

from what we are given to what we need?

Dimensional Analysis

- Method of calculation using a conversion factor.

Dimensional Analysis

Example we want to convert the distance 8 in.

to feet. (12in 1 ft)

Dimensional Analysis

Example we want to convert the distance 8 in.

to feet. (12in 1 ft)

Dimensional Analysis

Problem Convert the quantity from 2.3 x 10-8 cm

to nanometers (nm)

Dimensional Analysis

Problem Convert the quantity from 2.3 x 10-8 cm

to nanometers (nm) First we will need to

determine the conversion factors Centimeter (cm)

? Meter (m) Meter (m) ? Nanometer (nm)

Dimensional Analysis

Problem Convert the quantity from 2.3 x 10-8 cm

to nanometers (nm) First we will need to

determine the conversion factors Centimeter (cm)

? Meter (m) Meter (m) ? Nanometer (nm) Or 1 cm

0.01 m 1 x 10-9 m 1 nm

Dimensional Analysis

Problem Convert the quantity from 2.3 x 10-8 cm

to nanometers (nm) 1 cm 0.01 m 1 x 10-9 m 1

nm Now, we need to setup the equation where the

cm cancels and nm is left.

Dimensional Analysis

Problem Convert the quantity from 2.3 x 10-8 cm

to nanometers (nm) 1 cm 0.01 m 1 x 10-9 m 1

nm Now, fill-in the value that corresponds with

the unit and solve the equation.

Dimensional Analysis

Problem Convert the quantity from 2.3 x 10-8 cm

to nanometers (nm)

Dimensional Analysis

Problem Convert the quantity from 31,820 mi2 to

square meters (m2)

Dimensional Analysis

Problem Convert the quantity from 31,820 mi2 to

square meters (m2) First we will need to

determine the conversion factors Mile (mi) ?

kilometer (km) kilometer (km) ? meter (m)

Dimensional Analysis

Problem Convert the quantity from 31,820 mi2 to

square meters (m2) First we will need to

determine the conversion factors Mile (mi) ?

kilometer (km) kilometer (km) ? meter (km) Or 1

mile 1.6093km 1000m 1 km

Dimensional Analysis

Problem Convert the quantity from 31,820 mi2 to

square meters (m2) Now, we need to setup the

equation where the mi cancels and m is left. 1

mile 1.6093km 1000m 1 km

Dimensional Analysis

Problem Convert the quantity from 31,820 mi2 to

square meters (m2) Now, we need to setup the

equation where the mi cancels and m is left. 1

mile 1.6093km 1000m 1 km Notice, that the

units do not cancel, each conversion factor must

be squared.

Dimensional Analysis

Problem Convert the quantity from 31,820 mi2 to

square meters (m2)

Dimensional Analysis

Problem Convert the quantity from 31,820 mi2 to

square meters (m2)

Dimensional Analysis

Problem Convert the quantity from 31,820 mi2 to

square meters (m2)

Dimensional Analysis

Problem Convert the quantity from 14 m/s to miles

per hour (mi/hr).

Dimensional Analysis

Problem Convert the quantity from 14 m/s to miles

per hour (mi/hr). Determine the conversion

factors Meter (m) ? Kilometer (km) Kilometer(km)

? Mile(mi) Seconds (s) ? Minutes

(min) Minutes(min) ? Hours (hr)

Dimensional Analysis

Problem Convert the quantity from 14 m/s to miles

per hour (mi/hr). Determine the conversion

factors Meter (m) ? Kilometer (km) Kilometer(km)

? Mile(mi) Seconds (s) ? Minutes

(min) Minutes(min) ? Hours (hr) Or 1 mile

1.6093 km 1000m 1 km 60 sec 1 min 60 min 1

hr

Dimensional Analysis

Problem Convert the quantity from 14 m/s to miles

per hour (mi/hr). 1 mile 1.6093 km 1000m 1

km 60 sec 1 min 60 min 1 hr

Dimensional Analysis

Problem Convert the quantity from 14 m/s to miles

per hour (mi/hr). 1 mile 1.6093 km 1000m 1

km 60 sec 1 min 60 min 1 hr

Dimensional Analysis

Problem Convert the quantity from 14 m/s to miles

per hour (mi/hr). 1 mile 1.6093 km 1000m 1

km 60 sec 1 min 60 min 1 hr

End of Chapter Problems

1.2, 1.16a, 1.18, 1.20, 1.26, 1.36, 1.38, 1.44,

1.52, 1.63, 1.67