Question

As chief chemist at Superior Analytical Products (SAP) you must design an experiment to determine the density of an unknown liquid to three (3) significant figures. The density is of the order of 1 g/cm3. You have approximately 7 mL of the liquid and only graduated cylinders and balances are available for your use. Which of the following combinations of equipment will allow you to meet but not exceed your goal?

a. graduated cylinder with +0.1 mL uncertainty, balance with :0.1g.
b. graduated cylinder with ±001 mL uncertainty: balance with 101 g uncertainty.
c. graduated cylinder with t0.01 mL uncertainty balance with t0 01 g uncertainty.
d. graduated cylinder with ±0 001 mL uncertainty, balance with 10001 g uncertainty.

Answer 1

The correct answer is a

Step-by-step explanation:

The formula for density is mass ÷ volume. Hence, a balance is required to determine the mass while a measuring/graduated cylinder is required to determine the volume.

The ideal measuring cylinder and balance to be used should have an uncertainty of just 0.1 ml and 0.1 g respectively. This reduces the chances of the answer gotten from the formula above to be more than 3 significant figures.

For example, if the volume to be used is 4.0 ml and the mass of this volume is 3.5 g, the density will be

Density = 3.5 ÷ 4

Density = 0.875 g/cm³ or 0.875 g/ml

NOTE that cm³ is the same measurement as mL

The answer above is in 3 significant figures