Ch. 1

Question 1

True or false: Mass is the same thing as weight

Answer 1

False

Mass is the same anywhere. Weight depends on gravity

Question 2

What are physical properties?

Answer 2

Properties of an element that don’t involve a chemcial reaction/composition change.

Question 3

What are chemical properties?

Answer 3

A property of a substance that be observed only by reacting it to form another substance

C + O₂ = CO₂

Question 4

What is a pure substance?

Answer 4

A substance that has the same physical and chemcial properties throughout. Constant properties/composition

Question 5

What is an element?

Answer 5

A pure substance with only one type of atom.

E.g. Al or O₂, or N₄

Question 6

What is a mixture?

Answer 6

Two or more types of matter that can be present in varying amounts and can be separated by physical changes (like evaporation)

Question 7

What is a heterogeneous mixture?

Answer 7

A mixture with a composition that varies from point to point.

Think of a poorly mixed milkshake

Question 8

What is a homogenous mixture?

Answer 8

A mixture that exhibits a uniform composition and appears visually the same throughout

E.g. Gatorade, a well-mixed milkshake

Also known as a solution

Question 9

How do you find density?

Answer 9

d = m/v

Question 10

What is the mathematical relationship between density and volume?

Answer 10

They are inversely proportional

As one goes up, the other goes down.

Question 11

What are intensive properties?

Answer 11

A property independent of amount of substance present

Think physical and chemical properties

Question 12

What are extensive properties?

Answer 12

Properties that vary with quantity present

Think mass & volume

Question 13

What is a physical change?

Answer 13

A change in the state or properties of matter without any accompanying change in its chemical identites

Question 14

What is a chemical change?

Answer 14

A change that always produces one or more types of matter that differ from the matter present before the change

Question 15

Why do we use significant figures?

Answer 15

Every measurement has some uncertainty, which depends on the device used. So, we use significant figures to reflect the certainty and uncertainty.

Question 16

True or false: The first non-zero digit counts as a significant figure

Answer 16

True

Question 17

True or false: A trailing zero is not significant

Answer 17

False. IT is significant

e.g.) .0000750 has 3 significant digits, the 7, 5, and 0.

Question 18

Is this a big or a small number? 1.0 x 10^20

Answer 18

Big number

Question 19

How can you convert an exponential notation to regular numbers?

Answer 19

If the exponent (n) is positive, move the decimal n times to the right.
If the exponent (n) is negative, move the decimal n times to the left.

Question 20

True or false: Results calculated from a measurement are at least as uncertain as the measurement itself.

Answer 20

True

Question 21

How do you round a number resulting from adding/subtracting measurements together?

Answer 21

Round the result to the same number of decimal places as the number with the least number of decimal places (least certain value)

e.g.) 40.2g + 24.999913g = 65.2g (1 decimal place)

Your measurements are only as good as your least certain value

Question 22

How do you round a number resulting from multiplying/dividing measurements?

Answer 22

Round the result to the same number of digits as the number with the least number of significant figures

e.g.) 25.05g/0.000530g = 4.73 x 10^4 (three significant figures)

Question 23

How do you convert one measurement into another?

Answer 23

Multiply it by a conversion factor to divide out (or cancel out) the old unit while inserting a new unit.

e.g.) 9.26 lb x 4.53.59g/1 lb = 4.20 x 10^3 g (lb cancels out, gramstay