Significant Figures
How many significant figures are in 0.00620?
3 significant figures
Leading zeros do not count.
Express 87.5 in scientific notation.
8.75 x 101
Convert 2390 g to kilograms.
2390 g=2.39 kg
What are the two main categories of matter?
Pure substances and mixtures
What are the temperature and pressure values at STP?
Temperature: 0 °C
Pressure: 1 atm
How many significant figures are in 0.10040?
5 significant figures
Zeros between nonzero digits and trailing zeros in a decimal number are significant.
Express 0.000189 in scientific notation.
1.89 x 10-4
Convert 0.52 km to meters.
0.52 km=520 m
Classify air.
Homogeneous mixture
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.
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.
Express 3.87 x 105 in standard notation.
387,000
Convert 1500 mm to kilometers.
1500 mm=0.0015 km
or
1.5 x 10-3 km
Classify nitrogen.
Element
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.
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
Express 5.778 x 10-6 in standard notation.
0.000005778
Convert 0.75 kg to milligrams.
0.75 kg=750,000 mg
or
7.5 x 105 mg
Classify sodium hydroxide, NaOH.
Compound
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.
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
Calculate: (8.0 x10-2)(7.0 x10-5)
56x 10-7=5.6 x 10-6
Convert 1.08 cm3 to liters.
1.08 cm3=0.00108 L
or
1.08 x 10-3 L
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
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