SI UNITS & MEASUREMENTS
What SI unit would be most appropriate for measuring the volume of a small amount of liquid in a laboratory?
Milliliters (mL)
Convert 0.00085 kg to milligrams.
850 mg
A substance has a mass of 72 g and a density of 3 g/cm³. What is its volume?
24 cm³
A student measures the same object five times and gets nearly identical results. What characteristic does this demonstrate?
Precision
How many significant figures are in 0.00450 L?
3
A student needs to determine how much matter is present in a sample. What quantity is being measured, and what is its SI base unit?
Mass; kilogram (kg)
A sample has a mass of 2.75 × 10⁻³ kg. Express the mass in milligrams.
2,750 mg
A rectangular block measures 8 cm × 4 cm × 3 cm and has a mass of 384 g. What is its density?
4 g/cm³
The accepted value is 25.0 g. A student obtains:
24.9 g, 25.0 g, 25.1 g
Are the measurements accurate, precise, both, or neither?
Both accurate and precise
How many significant figures are in 6.020 × 10³ g?
4
A student records 0.0450 L of liquid. What quantity is being measured, and what equivalent volume in milliliters does this represent?
Volume; 45.0 mL
A graduated cylinder contains 2.35 × 10⁻² L of liquid. Express the volume in mL.
23.5 mL
A liquid has a density of 0.92 g/mL. How much mass would 275 mL of the liquid have?
253 g
The accepted value is 100.0 mL. Four students obtain:
Which student demonstrates both high accuracy and high precision?
Student A
Round 45.6782 g to 4 significant figures.
45.68 g
Put these measurements in order from smallest to largest:
0.75 kg, 750 mg, 0.75 g, 75 g
750 mg < 0.75 g < 75 g < 0.75 kg
A metal sample has a mass of 0.085 kg and a volume of 35 mL. Before calculating density in g/mL, what must the mass be converted to?
85 g
A rock has a mass of 84.6 g. When placed in a graduated cylinder, the water level rises from 35.0 mL to 68.5 mL.
What is the density of the rock?
2.53 g/mL
A balance consistently measures every sample as 2 g heavier than its actual mass. Is this more likely an issue with accuracy or precision?
Accuracy
Calculate and report the answer with the correct number of significant figures:
12.5 g ÷ 2.0 mL
6.3 g/mL
A graduated cylinder contains 35 mL of water. What physical quantity is being measured, and what SI-derived unit is commonly used for this measurement?
Volume; milliliters (mL)
A liquid has a volume of 0.00275 L and a mass of 2.20 g. Calculate its density in g/mL.
0.8 g/mL
A metal sphere has a radius of 2.0 cm and a mass of 268 g.Calculate the sphere's volume and density.
Volume ≈ 33.5 cm³
Density ≈ 8.00 g/cm³
A student obtains:
9.98 g, 10.01 g, 10.00 g, 10.02 g
The accepted value is 15.00 g.
What can you conclude?
High precision but low accuracy
Calculate and round correctly:
15.62 g + 4.1 g + 0.327 g
20.0 g