# [1pt] The barometric pressure measured outside an airplaneat 8 km (26248 ft) was 348 mmHg

1. [1pt] The barometric pressure measured outside an airplane
at 8 km (26248 ft) was 348 mmHg. Calculate the pressure
in kPa. Do not enter unit.

2. [1pt] If 637 dm3 of krypton at 218 kPa and 18C is compressed
into a 28.0-dm3 tank at the same temperature, what is
the pressure (in kPa) of krypton in the tank? Enter unit.

3. [1pt] A sample of 70.0 cm3 of argon gas at 19C was
contained at a pressure of 198 kPa in a J-shaped tube with
mercury. Later the temperature changed. When the mercury
level was adjusted to give the same pressure of argon, the gas
volume changed to 45.3 cm3. What was the nal temperature
of the argon? Give answer in C. Do not enter unit.

4. [1pt] Methanol can be produced in industrial plants by
reacting carbon dioxide with hydrogen in the presence of a catalyst.
Water is the other product. How many volumes of hydrogen
are required for each volume of carbon dioxide when each
gas is at the same temperature and pressure? Just enter the
number.

5. [1pt] In an experiment, you ll a heavy-walled 3.00-L ask
with methane gas, CH4. If the ask contains 3.47 g of methane
at 28C, what is the gas pressure in atm? Enter unit.

6. [1pt] A 4.00-L ask was used to collect a 5.44-g sample
of propane gas, C3H8. After the sample was collected, the gas
pressure was found to be 718 mmHg. What was the temperature
of the propane in the ask? Give answer in C. Do not enter
unit.

7. [1pt] Calculate the density of hydrogen sul de gas, H2S
at 34C and 893 mmHg. Obtain the density in grams per liter.
Do not enter unit.

8. [1pt] You vaporize a liquid substance at 100C and 734
mmHg. The volume of 0.553 g of vapor is 224 mL. What is the
molecular weight of the substance? Give answer in amu. Do not
enter unit.

9. [1pt] Magnesium burns in air to produce magnesium oxide,
MgO, and magnesium nitride, Mg3N2. Magnesium nitride
reacts with water to give ammonia.
Mg3N2(s) + 6H2O(l) ! 3Mg(OH)2(s) + 2NH3(g)
What volume (in L) of ammonia gas at 25C and 746 mmHg
will be produced from 4.64 g of magnesium nitride? Enter unit.

10. [1pt] Sodium hydrogen carbonate is also known as baking
soda. When this compound is heated, it decomposes to
sodium carbonate, carbon dioxide, and water. Write the balanced
equation for this reaction.

11. [1pt] What volume (in liters) of carbon dioxide gas at
72C and 743 mmHg will be produced from 25.7 g of sodium
hydrogen carbonate? Do not enter unit.

12. [1pt] The atmosphere in a sealed diving bell contained
oxygen and helium. If the gas mixture has 0.300 atm of oxygen
and a total pressure of 3.00 atm, calculate the mass of helium
(in g) in 10.0 L of the gas mixture at 23C. Enter unit.

13. [1pt] An aqueous solution of ammonium nitrite, NH4NO2,
decomposes when heated to give o
nitrogen, N2.
NH4NO2(s) ! 2H2O(g) + N2(g)
This reaction may be used to prepare pure nitrogen. How many
grams of ammonium nitrite must have reacted if 3.53 dm3 of
nitrogen gas was collected over water at 24C and 96.7 kPa? Do
not enter unit.

14. [1pt] A steel bottle contains 12.7 L of a gas at 11.2 atm
and 22C. What is the volume (in L) of gas at STP? Enter unit.

15. [1pt] The combustion method used to analyze for carbon
and hydrogen can be adapted to give percentage N by collecting
the nitrogen from combustion of the compound as N2. A sample
of a compound weighing 8.78 mg gave 1.81 mL N2 at 27C and
746 mmHg. What is the percentage N in the compound? Do
not enter unit.

16. [1pt] Raoul Pictet, the Swiss physicist who rst lique ed
oxygen, attempted to liquefy hydrogen. He heated potassium
formate, KCHO2, with KOH in a closed 2.50-L vessel.
KCHO2(s) + KOH(s) ! K2CO3(s) + H2(g)
If 49.0 g of potassium formate reacts in a 2.50-L vessel, which
was initially evacuated, what pressure (in atm) of hydrogen will
be attained when the temperature is nally cooled to 20C? Use
the preceding chemical equation and ignore the volume of solid
product. Enter unit.

17. [1pt] A 48.90-mL sample of a 0.2040 M acid reacts with
an excess of Na2CO3 to form 125.0 mL CO2 at 722 mmHg and
17C. If the acid is either HCl or H2SO4, which is it? Do not
use subscript.

18. [1pt] A sample of zinc metal was reacted with an excess
of hydrochloric acid.
Zn(s) + 2HCl(aq) ! ZnCl2(aq) + H2(g)
All of the zinc reacted, and the hydrogen gas was collected over
water at 16C; the barometric pressure was 755 mmHg. The apparatus
was similar to that shown in Figure 5.20, but the level
of water inside the tube was 33.0 cm above the level outside the
tube. If the volume of gas in the tube is 21.2 mL, how many
grams of zinc were there in the sample? Do not enter unit. The
density of Hg is 13.596 g/mL and the density of water is 1.000
g/mL.

19. [1pt] A mixture contained zinc sul de, ZnS, and lead
sul de, PbS. A sample of the mixture weighing 6.11 g was reacted
with an excess of hydrochloric acid. The reactions are
ZnS(s) + 2HCl(aq) ! ZnCl2(aq) + H2S(g)
PbS(s) + 2HCl(aq) ! PbCl2(aq) + H2S(g)
If the sample reacted completely and produced 1.044 L of hydrogen
sul de, H2S, at 22C and 741 mmHg, what were the percentages
of ZnS and PbS in the mixture. Enter the percentage
for ZnS rst, then PbS. Do not enter units.

20. [1pt] A mixture of Ne and Ar gases at 349 K contains
twice as many moles of Ne as of Ar and has a total mass of 50.0
g. If the density of the mixture is 3.86 g/L, what is the partial
pressure (in atm) of Ne? Enter unit.