CHEMISTRY REVIEW SATURDAY
JUNE 10, 2006 10:00-2:00
1) A gas has a volume of 2000.0cm3 and a mass 6.0 grams. Calculate :
a. The density at STP?
D = mass
volume
2000.0cm3 = 2000.0 mL = 2.0 Liters
D = 6.0 g = 3 g/L
2.0 L
b. The number of moles at STP.
1 mole = 22.4 L
at STP, Avogadro’s law
If one mole is 22.4 liters, then you can RATIO your volume to that
relationship, therefore
1mol = x mol where x = 0.08928 round to (2 s.f.) 0.089mol
22.4L 2.0 L
c. The molar mass at STP.
1 mole any gas = 22.4L at STP
Set up a ratio of x/22.4 = 6.0g/2.0L
Mass = molar mass at STP
Vin L
22.4L
6.0g = molar mass
2.0L
22.4L
, molar mass = 67.
2) The compound N2O5 reacts to form N2 and O2 . Answer the following:
a. Write the reaction.
2 N2O5  2N2 + 5 O2
b. Balance the reaction.
c. Name three things conserved in EVERY reaction.
-mass, energy, charge
d. What classification of reaction is this?
- decomposition A  B + C
3) For the compound Co(NO3)3,
a. Write the dissociation
Co(NO3)3   Co3+ + 3 NO3 -
b. Compare dissociation and decomposition reactions.
c. Which species would conduct from this reaction.
4) For the reaction N2(g) + H2(g)  NH3(g):
a. Balance the reaction.
N2(g) + 3H2(g)  2NH3(g)
b. Classify the reaction.
Synthesis A + B C
c. If 2.0 liters of N2(g) reacts completely, how many liters of
NH3(g) are produced?
Set up a ratio of N2 to NH3.
N2 = 1 L = 2.0 L
x = 4.0 L of NH3(g)
NH3 2 L
xL
* At constant temperature and pressure you can ratio VOLUMES.
d. If 9 liters of H2(g) is consumed, how much ammonia is
produced?
H2 = 3 L = 9 L
x = 6 L of NH3(g)
NH3 2 L
xL
e. If 30. Liters of ammonia are produced, how much H2(g) was
consumed?
H2 = 3 L = x L
x = 45. L of H2(g)
NH3 2 L 30. L