MATTER AND MEASUREMENT

Question 1

Describe the 4 states of matter by the kinetic molecular theory

Answer 1

Solid: tightly packed particles
Liquid: loosely connected particles
Gas: free particles
Plasma: free particles with ions and electrons, it can conduct electricity

Question 2

Describe a pure substance

Answer 2

• Elements or compounds

- Compounds can be further reduced into 2 or more elements (elements are the base)

Question 3

Describe a mixture

Answer 3

• Can seperate into a pure substance
• Can be heterogeneous (non-uniform)
• Can be homogenous (uniform)

Question 4

Describe an alloy

Answer 4

Combination of elements tailored for a purpose (e.g., gold is soft, other metals are added for strength), they are technically a mixture

Question 5

What is the difference between physical and chemical changes of matter

Answer 5

• Chemical: changes the chemical composition, results in a new substance
• Physical: changes without changing the composition of the substance (e.g., boiling, melting, dissolving)

Question 6

What is the formula for density?

Answer 6

Density = mass/volume
g/mL for liquids and solids
g/L for gases

Question 7

What is specific gravity?

Answer 7

Density of a substance compared to water as a standard

Question 8

1. What is the measurement for temperature in SI

2. What is absolute 0?

Answer 8

1. Kelvin

2. 0 Kelvin (0K), -273 degrees Celsius, when molecules stop moving

Question 9

What is heat and what are the SI units?

Answer 9

Heat is the thermal energy transferred from a hotter system to a cooler system

The most common units are calorie and Kcal (1Kcal = 1000cal)

Joule is the SI unit of heat

Question 10

What is specific heat?

Answer 10

The amount of heat needed for 1g of a substance to raise by 1 degree

Question 11

Define the terms:

1. Accuracy
2. Precision
3. Significant figures

Answer 11

1. Accuracy is the closeness of a measured value from a known value
2. Precision is the closeness of 2 or more measured values
3. Significant figures are the relevant number of digits in a value that contribute to accuracy

Question 12

Define the law of definite proportions

Answer 12

A chemical compound is always made up of the exact same proportion of elements by mass, these proportions will always hold true regardless of the amount of compound present

Question 13

What is the relation between heat and temperature?

Answer 13

Heat describes the transfer of thermal energy between molecules within a system. Heat measures how energy moves or flows. Temperature describes the average kinetic energy of molecules within a material or system.