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D-4
(a)
The volume available to the gas in the flask is V1 and the temperature of the flask at the start of
the reaction is T1. Use Charles' Law to calculate V2, the volume to which V1 expands at the
temperature at the end of the experiment, T2.
(b)
Subtract V1 from V2 to get
V, the excess volume.
(c)
Assume that
V goes into the buret. Calculate this excess volume as a percent of the final
volume of gas collected in the buret.
You will be asked to compare the experimentally determined value of R with the accepted literature value
of R. The percent error in your answer is defined as:
Percent error =
experimental value - accepted value
accepted value
x 100%
The experimentally determined value of R should be within ±10% of the literature value of R, if the
experiment is performed correctly.
ADVANCE STUDY ASSIGNMENT
1. 19.00 mL of 0.0824 M HSO3NH2 is used for one run in this experiment, what is the minimum volume
of 0.250 M NaNO2 that should be used to ensure that complete reaction occurs? Answer: 6.26 mL
2.
If an additional 4.0 mL of the NaNO2 solution is added to the HSO3NH2 of problem 1, what effect will
this have on the amount of N
2(g)
produced? Answer: The additional NaNO2 will not increase the
volume of N
2(g)
produced because HSO3NH2 is the limiting reagent. Excess NaNO2 merely ensures
that the moles of N
2(g)
formed equals moles of sulfamic acid that you start with.
3.
(a) What is the vapor pressure of water directly above a container of water at 22.3 °C?
Answer: 20.2 mm Hg (Use linear interpolation from the values given at 22 and
23 °C in the table of water vapor pressure on the Chemistry Data Sheet).
(b) Assume that, besides water, only N
2(g)
is present. If the atmospheric pressure is 705 mm Hg,
what is the partial pressure of N
2(g)
?
Answer: 685 mm Hg
4. If the water column in a buret is 10.0 cm high, what is P
wc
(mm Hg) at room temperature? (ie. ~22
C)
Answer: 7.37 mm Hg
REAGENTS AND EQUIPMENT
0.250 M NaNO2 (Sodium nitrite)
Tweezers
Squeeze bulb
0.082x M HSO3NH2 (Sulfamic acid)
Glass vial
50 mL buret
U-tube connected with clear tubing to a glass tube in a rubber stopper (special issue)
