Chemistry Unit 1 Review

Significant Figures

100

How many significant figures are in 0.00620?

3 significant figures

Leading zeros do not count. 

200

How many significant figures are in 0.10040?

5 significant figures

Zeros between nonzero digits and trailing zeros in a decimal number are significant.

300

How many significant figures are in 16.0000?

6 significant figures

All digits shown, including trailing zeros after the decimal, are significant because all zeros to the right of a decimal point and to the right of a non-zero digit are significant.

400

Calculate with proper significant figures: 25.37+5.198+147.2

25.37+5.198+147.2=177.768

Round to the least number of decimal places:

177.8

500

Calculate with proper significant figures: 

6.35 x 1.05 x 2.168

6.35 x 1.05 x 2.168=14.45514

Round to 3 significant figures:

14.4

Scientific Notation

100

Express 87.5 in scientific notation.

8.75 x 10¹

200

Express 0.000189 in scientific notation.

1.89 x 10^-4

300

Express 3.87 x 10⁵ in standard notation.

387,000

400

Express 5.778 x 10^-6 in standard notation.

0.000005778

500

Calculate: (8.0 x10^-2)(7.0 x10^-5)

56x 10^-7=5.6 x 10^-6

Unit Conversions

100

Convert 2390 g to kilograms.

2390 g=2.39 kg

200

Convert 0.52 km to meters.

0.52 km=520 m

300

Convert 1500 mm to kilometers.

1500 mm=0.0015 km

or

1.5 x 10^-3 km

400

Convert 0.75 kg to milligrams.

0.75 kg=750,000 mg

or

7.5 x 10⁵ mg

500

Convert 1.08 cm³ to liters.

1.08 cm³=0.00108 L

or

1.08 x 10^-3 L

Matter Classification

100

What are the two main categories of matter?

Pure substances and mixtures

200

Classify air.

Homogeneous mixture

300

Classify nitrogen.

Element

400

Classify sodium hydroxide, NaOH.

 Compound

500

Classify each mixture as homogeneous or heterogeneous:

• Chocolate-chip ice cream

• Green ink

• Salad

• Kool-Aid

• Chocolate-chip ice cream: heterogeneous

• Green ink: homogeneous

• Salad: heterogeneous

• Kool-Aid: homogeneous

Phase Diagrams/ Physical vs Chemical

100

What are the temperature and pressure values at STP?

Temperature: 0 °C

Pressure: 1 atm

200

What is the difference between a solid and a liquid?

A solid has a definite shape and definite volume.

A liquid has a definite volume but takes the shape of its container.

300

What is the difference between physical and chemical changes?

A physical change does not change the substance’s identity.

A chemical change produces one or more new substances.

400

Name a common substance that demonstrates sublimation. Is it naturally occurring on Earth?

Dry ice, or solid carbon dioxide, demonstrates sublimation.

Solid carbon dioxide does not naturally occur on Earth under normal surface conditions.

500

If the substance starts at 1.25 atm and 300 °C and the pressure drops to 0.25 atm, what phase transition occurs?

Gas to solid: deposition