Chemists often use molarity M , in moles/liter , to measure the concentration of solutions. Molarity is a common unit of concentration because the...

Chemists often use molarity M

, in moles/liter

, to measure the concentration of solutions. Molarity is a common unit of concentration because the volume of a liquid is very easy to measure. However, the drawback of using molarity is that volume is a temperature-dependent quantity. As temperature changes, density changes, which affects volume. Volume markings for most laboratory glassware are calibrated for room temperature, about 20

∘

C

.

Fortunately, there are several other ways of expressing concentration that do not involve volume and are therefore temperature independent.

A 2.600×10−2 M

 solution of NaCl

 in water is at 20.0

∘

C

. The sample was created by dissolving a sample of NaCl

 in water and then bringing the volume up to 1.000 L

. It was determined that the volume of water needed to do this was 999.3 mL

 . The density of water at 20.0

∘

C

 is 0.9982 g/mL

.

Part A

Calculate the molality of the salt solution.

Express your answer to four significant figures and include the appropriate units.