DENSITY OF SODIUM CHLORIDE SOLUTIONS

DENSITY OF SODIUM CHLORIDE SOLUTIONS
CHEMICALS AND MATERIALS
NaCl(s)
water
EQUIPMENT TO BE CHECKED OUT
5-mL graduated pipet
250mL volumetric flask
25mL buret
25mL Erlenmeyer flask with stopper
SAFETY
Goggles must be worn in the laboratory.
WASTE DISPOSAL
All solutions may be rinsed down the sink
EXPERIMENTAL PROCEDURE:
Your instructor will assign you a specific molarity of sodium chloride solution to prepare.
You will prepare 250 mL of this solution and then measure its density by weighing specific
volumes of the solution on the analytical balance. Your instructor may assign one or all of
the methods for determining density from steps 2-4 below.
1. Prepare 250 mL of your assigned concentration of sodium chloride solution. Record
the exact mass of sodium chloride used.
2. Use your 5-mL graduated pipet to transfer 5.00 mL of your prepared solution to the
25-mL volumetric flask (keep stopper on after transferring to avoid evaporation
losses) and measure the mass of this solution on an analytical balance. Repeat this
procedure until you have 5 consecutive trials that agree within 0.2% (or about 0.02 g).
3. Use your 10-mL volumetric pipet to transfer 10.00 mL of your prepared solution to
the 25-mL volumetric flask (keep stopper on after transferring to avoid evaporation
losses) and measure the mass of this solution on an analytical balance. Repeat this
procedure until you have 5 consecutive trials that agree within 0.2% (or about 0.02 g).
4. Use a buret to sequentially transfer approximately 5 mL aliquots of your solution to
the pre-weighed weighing vial and weigh the transferred solution (do not empty the
weighing vial—add each additional 5mL to it). Repeat until you have delivered a
total of 20 mL of solution to your weighing vial. Note that it is not important to
transfer exactly 5.00 mL each time, but it is important to know precisely what volume
of solution was transferred—record the exact buret readings.
66