Sig Figs
Which digit is the estimated digit in 4.52 g?
2
Write 72,000 in scientific notation with 2 significant figures.
7.2 × 10⁴
Convert 325 mL to liters.
0.325 L
Convert –15 °C to Kelvin.
258 K
Density formula = ?
mass ÷ volume
How many significant figures are in 0.00340 L?
3
Round 0.0045678 to 2 significant figures.
0.0046
A runner completes a 10.0 km race. How many meters is this?
10,000 m
What is the boiling point of water in Kelvin?
373 K
A rock has a mass of 125 g and a volume of 48.2 mL. Will it sink or float?
Sink, density = 2.59 g/mL
Round 23.6789 g to 3 significant figures.
23.7
Why do chemists round answers instead of keeping every decimal?
Show how precise something is - Can't have too many decimal points - Convenience
How many millimeters are in 5.4 km?
5.4 × 10⁶ mm
A gas cools from 300 K to 250 K. What is the temperature change in °C?
50 °C
A cube of copper measures 3.0 cm on each edge. Density = 8.96 g/cm³. What is its mass?
243 g
True or False: Zeros at the beginning of a number are always significant.
False
Multiply 2.40 m × 3.1 m. Report with correct units and sig figs. (Hint: be careful about units!!!)
7.4 m²
Convert 2.45 × 10⁵ mg to kilograms.
0.245 kg
Helium boils at 4 K. What is this temperature in °C?
–269 °C
A block of metal has a density of 8.90 g/cm³ and a volume of 12.5 cm³. What is its mass?
111 g
Express 0.000245 m in scientific notation with correct sig figs (and units)
2.45 × 10⁻⁴ m
Divide 15.62 g ÷ 2.4 mL. Report answer with correct sig figs.
6.5 g/mL
Convert 4.50 gallons to liters (1 gal = 4 qt, 1 qt = 0.946 L)
17.0 L
If the temperature of a substance changes by 100 K, by how much does it change in °C?
100 °C
A student measures a 50.8 g sample of metal with a volume of 3.18 mL. Density = 16.0 g/mL. Is it pure gold?
No, gold = 19.3 g/mL