Chapter 3: Measurements and Calculations

Question 1

What are the three common scales used when measuring temperature in chemistry?

Answer 1

Celsius
Kelvin
Fahrenheit

Question 2

What does the temperature scale Kelvin represent?

Answer 2

The Absolute Scale

Question 3

What is the formula to convert Kelvin to Celsius?

Answer 3

°C = K - 273

^ if this is not in your calculator, add it now.

Question 4

What formula is used to convert Celsius to Fahrenheit?

Answer 4

°F = 9/5°C + 32

^ if this is not in your calculator, add it now.

Question 5

What formula is used to convert Fahrenheit to Celsius?

Answer 5

°C = 5/9(°F - 32)

^ if this is not in your calculator, add it now.

Question 6

Define significant figures and their rules:

Answer 6

each of the digits of a number that are used to express it to the required degree of accuracy, starting from the first NONZERO digit.

examples:
6.658 has four significant figures
129 has 3 significant figures
5,007 has four significant figures

Trailing zeros in a number are only significant if the number contains a decimal point.

examples:
100.4 has 4 significant figures
100 has 1 significant figure

Zeros in the beginning of a number whose only function is to place the decimal point are not significant.

example:
0.0025 has 2 significant figures

Zeros following a decimal significant figure ARE significant.

examples:
0.000470 has 3 significant figures
0.47000 has 5 significant figures

Question 7

Determine the number of significant figures:

5.432g

Answer 7

4

Question 8

Determine the number of significant figures:

2873.0cm

Answer 8

5

Question 9

Determine the number of significant figures:

2500.0cm

Answer 9

5

Question 10

True or False:

When multiplying and dividing, limit and round to the least number of significant figures in any of the factors.

Answer 10

True.

Example:

23.0cm x 432cm x 19cm = 188,784cm^3

The answer is expressed as 190,000cm^3 since 19 cm in the problem has only two significant figures.

Question 11

True or False:

When adding and subtracting, limit and round your answer to the least number of whole numbers that make up your answer.

Answer 11

False.

When adding and subtracting, limit and round your answer to the least number of DECIMAL PLACES in ANY of the numbers that make up your answer.

Example:

123.25mL + 46.0mL + 86.257mL = 255.507mL

The answer is expressed as 255.5mL since 46.0mL in the problem only has one decimal place.

Question 12

Add & express in sig fig:

12cm + 0.031cm + 7.969cm =

Answer 12

20cm

Question 13

Add & express in sig fig:

63.489cm + 126.2cm + 68.85cm + 12.05cm =

Answer 13

270.6 cm

Question 14

Multiply & express in sig fig:

5.0cm x 5cm =

Answer 14

20 cm^2

Question 15

Multiply & Express in sig fig:

4.218cm x 6.5cm =

Answer 15

27cm^2

Question 16

What type of units is mass measured?

Answer 16

Kilograms (kg)

Question 17

What type of units is length measured?

Answer 17

meters (m)

Question 18

What type of units is used to measure time?

Answer 18

seconds (s)

Question 19

What type of units is used to measure temperature?

Answer 19

kelvin (K)

Question 20

Do you have this cheat sheet in your calculator?

Answer 20

if not, add it now :)

Question 21

Review your density (rainbow) lab

Answer 21

I don’t have much to give you on density – so look over the lab

Question 22

Express 1,870,000 in scientific notation.

Answer 22

1.87 x 10^6

Question 23

The number 0.00003007 expressed in exponential notion is:

Answer 23

3.007 x 10^-5

Question 24

The SI prefix that corresponds to a factor of 10^-3 is:

Answer 24

milli

Question 25

The number of milliliters in 0.067 liter is:

Answer 25

36.7 mL

Question 26

Consider the numbers 23.68 and 4.12

The sum of these numbers has significant figures, and the product of these numbers has significant figures. what are they?

Answer 26

4 and 3

Question 27

Which of the following statements is true?

A. A change of 1°C is larger than a change of 1°F, but smaller than a change of 1 K.

B. A change of 1°F is larger than a change of 1°C, but smaller than a change of 1 K.

C. A change of 1°C is larger than a change of 1°F, and equal to a change of 1 K.

D. A change of 1°F is larger than a change of 1°C, and equal to a change of 1 K.

Answer 27

A change of 1°C is larger than a change of 1°F, and equal to a change of 1 K.

Question 28

A 15.0-mL sample of a liquid has a mass of 12.3 g. What is the density of the liquid?

Answer 28

0.820 g/mL

Question 29

The beakers shown in the image have different precisions as shown.

A. Report the volume of water beaker 1 with the proper number of significant figures.

B. Label the digits in each measurement from part A as “certain” or “uncertain.”

C. You pour the water from these three beakers into one container. What is the volume of liquid in the container reported to the correct number of significant figures?

Answer 29

A –
beaker 1: 26.4mL

B –
2 & 6 are certain, 4 is uncertain

C –
81 mL