Week 1: Introduction to Chemistry, Matter and Measurements

1. Observation

2. Hypothesis

3. Experiments

What are the “Steps of Scientific Approach”

Observation

Gathering of data (qualitative & quantitative)

Hypothesis

Tentative explanation for the observation

Experiments

Performed to test the validity of the hypothesis

Experiments

Always produce new information

Law

summarizes a series of related observations.

Theory

gives the underlying reasons for them.

Matter

is anything that has mass and occupies space

Solid, Liquid, and Gas

Matter exists in three different states:

• Constant Volume

• Constant Shapea

• Highest Density

Solid

• Constant volume

• Changing shape

• Medium Density

Liquid

• Changing volume

• Changing shape

• Lowest density

Gas

Gas

Which state of matter has the lowest density?

Solid

Which state of matter has a constant shape and constant volume?

Pure substance and Mixture

What are the classifications of Matter?

Element and Compound

What are the classifications of a Pure Substance

Heterogeneous and Homogeneous

What are the classifications of a Mixture

Pure substance

made up of only one component, and its composition is invariant (it does not vary from one sample to another).

Elements

Cannot be broken down into simpler substances

Compounds

Can be broken down into simpler substances

mixture

is composed of two or more components in proportions that can vary from one sample to another.

Heterogeneous and Homogeneous

There are two types of mixtures

Heterogeneous mixture, and an example is wet sand

one in which the composition varies from one region of the mixture to another, and give an example.

Homogeneous mixture, and an example is sweetened tea

one with the same composition throughout

Mixtures

are separable because the different components have different physical or chemical properties

Decanting

A mixture of sand and water can be separated by ______

Decanting

carefully pouring off the water into another container

Distillation

A homogeneous mixture of liquids can usually be separated by ________

Distillation

A process in which the mixture is heated to boil off the more volatile (easily vaporizable) liquid.

1. When a mixture of liquids with different boiling points is heated….

2. The most volatile component boils first…..

3. The vapor is then cooled and collected as pure liquid.

Explain the distillation process.

Filtration

A mixture of an insoluble solid and a liquid can be separated by a __________.

Filtration

process in which the mixture is poured through filter paper in a funnel.

1. When a mixture of a liquid and a solid is poured through a filter paper….

2. The filter paper traps the solid.

3. The liquid component passes through and is collected.

Explain the filtration process.

Physical Changes

Changes that alter only the state or appearance of a substance, but not its composition.

do not change

The atoms or molecules that compose a substance _____________ their identity during a physical change.

• Crushing a can

• Melting an ice cube

• boiling water

• mixing sand with water

• breaking glass

Examples of Physical Change

Chemical Change

Changes that alter the composition of matter.

Chemical Change

During a chemical change, atoms rearrange, transforming the original substances into different substances.

The rusting of iron is a chemical change.

Give an example of chemical change

Physical property

is a property that a substance displays without changing its composition.

Chemical property

is a property that a substance displays only by changing its composition via a chemical change (or chemical reaction).

physical property

The smell of gasoline is a ____________.

• Odor

• Taste

• Color

• Appearance

• Melting point

• Boiling point

• Density

Properties of physical change.

• Flammability

• Corrosiveness

• Acidity

• Toxicity

Properties of chemical change.

Physical

Cutting

Chemical

Burning

Physical

Freezing

Physical

Dissolving

Phase Change

is a change from one phase (state of matter) to another

• ‏Sublimation

• Deposition

• Melting

• Freezing

• Condensation

• Vaporization

What are the 6 phase changes

Sublimation

Solid to Gas

Deposition

Gas to solid

Condensation

Gas to Liquid

Vaporization

Liquid to gas

Melting

Solid to liquid

Freezing

Liquid to Solid

Melting point

is the temperature at which a solid changes to a liquid.

0 Degrees Celsius

What is the melting point of water?

Freezing point

is the temperature at which a liquid changes to a solid.

0 Degrees celsius

What is the freezing point of water?

Yes

is the freezing point and the melting point the same?

Physical and Chemical changes

only happen when energy is applied (melting of ice, freezing of water, etc.)

Energy

is the capacity to do work.

Work

is defined as the action of a force through a distance

W = F x d

Formula for work

Potential Energy

energy associated with position or composition.

Kinetic Energy

energy associate with motion.

Total Energy

of an object is the sum of its potential energy and kinetic energy.

Potential Energy

What type of energy is chemical energy?

Units

standard quantities used to specify measurements—are critical.

Metric System

units used in most of the world

English system

units used in the United States

International System of Units

Scientists use the __________________ (SI), which is based on the metric system.

Meter (m)

What is the SI unit for length?

Kilogram (kg)

What is the SI unit for mass?

Second (s)

What is the SI unit for time?

Kelvin (K)

What is the SI unit for temperature?

Mole (mol)

What is the SI unit for amount of substance?

Ampere (A)

What is the SI unit for Electric current?

Candela(cd)

What is the SI unit for Luminous Intensity?

Mass

of an object is a measure of the quantity of matter within it.

weight

of an object is a measure of the gravitational pull on its matter.

temperature

is a measure of the average amount of kinetic energy of the atoms or molecules that compose the matter.

heat

Temperature also determines the direction of thermal energy

transfer, or what we commonly call ______.

Thermal Energy

transfers from hot to cold objects.

Fahrenheit degree

is five-ninths the size of a Celsius degree.

Celsius and kelvin

______ degree and the _____ degree are the same size.

K = C + 273.15

Formula for Celsius to kelvin

C = (F - 32) / 1.8

Formula for Celsius to Fahrenheit

Density

is the ratio of a substance’s mass to volume; it has units of mass/volume.

kg/m3

what is the unit for density

D = m/v

Formula for density

Accuracy and Precision

In chemistry, it is important to have ________ and ________.

Accuracy

how close your measurements are to the true value

Precision

how close your measurements are to each other