Chapter 1- Measurements in Chemistry

Matter

Anything that has mass and occupies space.

Energy

The ability to do work to accomplish some change.

Ways to categorize matter:

1. By state

2. By compisition

Gas

1. Particles are widely spread

2. No definite shape or volume

Liquid

1. Particles are closer together

2. Definite volume but no definite shape

Solid

1. Particles are very close together

2. Definite shape and definite volume

All of the following are examples of matter except

A) Heat

B) Air

C) Water

D) Salt

E) Plants

Answer: Heat

Explanation: It is a form of energy, not a physical substance made of atoms or molecules

Which of the following is a physical property?

A) Flammability

B) Conductivity

C) Ability to support combustion

D) Corrosiveness

E) Inertness

Answer: Conductivity

Explanation: It measures a substance’s ability to conduct heat or electricity without changing its chemical composition.

Physical properties:

1. Color

2. Hardness

3. Odor

4. Taste

Chemical properties:

1. Flammability

2. Acidity

What is a chemical property of aspirin?

Answer: It does not decompose when protected from moisture.

Which of the following causes a chemical change?

A) Winding an alarm clock

B) Metabolizing fat

C) Slicing a tomato

D) Digging a hole

E) Pumping gasoline

Answer: B) Metabolizing fat

Which factor determines the state of matter in which a substance exists?

A) Amount

B) Color

C) Density

D) Odor

E) Temperature

Answer: E) Temperature

A pure substance…

always has the same elemental composition.

What is an observation that demonstrates that a solid sample is a compound?

Answer: It cannot be broken down into simpler substance by physical methods.

Intensive properites

A property of matter that is independant of the quantity of the substance.

Examples: Color, melting point.

Extensive properties

A property of matter that depends on the quantity of a substance.

Examples: Mass, volume.

Is density intensive or extensive?

Answer: Intenstive

Explanation: If you divide a sample of a substance, its density remains the same. This is because density is a ratio of mass to volume (M/V), so as the mass of a substance increases, its volume increases proportionally, keeping the density constant. 

Mass in the metric system is measured by…

Grams or any weight.

1 lb = 454 g

Length in the metric system is measured by…

Meter (m)

1 yard = 0.914 m

Volume in the metric system is measured by…

Liter (L)

1 qt = 0.946 L

Accuracy

The degree of agreement between true value and the measured value.

Error

The difference between the true value and our estimation.

1. Random

2. Systematic

Precision

A measure of the agreement of replicate measurements.

Deviation

Amount of variation present in a set of replicate measurements.

Celcius formula

Farhenheit - 32 / 1.8

Farhenheit formula

1.8 x Celcius + 32

Kelvin Formula

*C + 273.15

What is the temperature at which the Celsius and Farhenheit scales read the same?

-40*

Kinetic energy

The energy of motion (energy of action)

Potential energy

The energy of position (stored energy)

Units of energy

1. Calorie (not food calorie) or Joule

2. 1 calorie (cal) = 4.18 joules (j)

3. kilocalorie (kcal) = food calorie

4. 1 kcal= 1 calorie = 1000 calories (not food calorie)

Concentration

The number or mass of particles of a substance contained in a specified volume.

Specific gravity

The ratio of the density of the object in question to the density of the pure water at 4 degrees C.

Specific gravity formula

density of object (g/mL) / density of water (g/mL)

*Note: Specific gravity is unitless because the 2 units cancel out from division.