Cindy Cai
Ch. 10 & 24 gas & complex ion Rx test [50 points] AP Chemistry
1. Give the formulas to show the reactants and products for the following chemical reactions.
Each occurs in aqueous solution unless otherwise indicated. Represent substances in solution as
ions if the substance is extensively ionized. Omit formulas for any ions or molecules that are
unchanged by the reaction. In all cases a reaction occurs. You need not balance (the coefficients
in the reactions). Pick 5 problems, only. [15 points]
a. mix solutions of iron (II) chloride and a concentrated solution of ammonia
FeCl2 + NH3  FeNH3Cl
b. sodium metal reacts with oxygen gas
4Na + O2  2Na2O
c. excess sodium cyanide solution added to a solution of silver nitrate
NaCN + AgNO3  AgCN + NaNO3
d. mix solutions of sodium sulfide and zinc fluoride
Na2S + 2ZnF  2NaF + Zn2S
e. an acidic solution of potassium permanganate reacts with silver
8H+ +MnO4- + 5e- Mn+2 + 4H2O
5(Ag Ag+ + e-)
8H+ +MnO4- + 5Ag  Mn+2 + 4H2O + Ag+
f. copper (II) hydroxide reacts with excess potassium cyanide solution
4 Cu + 8 KCN + 2 O2 + 2H2O → 4 K[Cu(CN)2] + 4 KOH
Cu + 2 CN- +2 O2 + 2H2O  [Cu(CN)2]-2 + 4 OHg. copper metal in dilute nitric acid
Cu  Cu+2 + 2eH+ + NO3- + 2e-  NO + 2OHCu + H+ + NO3-  Cu+2 + NO + 2OHFor problems involving calculations, show your work in an organized manner, includes any
relevant formula / equation, the proper units in your work and answer, and the proper number of
significant figures in your answer.
2. 100. mL 250. mM HCl reacts with 1.0 g Mg at 26◦C (where PH2O = 25 torr). Hydrogen gas was
collected over water, where the height of water inside and outside of the container was equal (i.e.
Pgas = Patm = 1.0 atm). [15 points]
a. # moles of H2 produced = __.
2HCl + Mg  H2 + MgCl2
(
(
) = 0.025 mole HCl limited
1g
= 0.041 Mg
0.025 mole HCl
= 0.0125 mole H2
b. # mL H2 produced = __.
PV = nRT
V=
=
= 0.307 L
= 307 mL
c. # mL H2 produced at STP = __.
@ STP: 22.4 mole = 1 L
0.0125 mole H2
= 0.558 mL
3. 2.0 mL of an unknown compound was completely vaporized in a 125 mL flask immersed in a
90◦C water bath, then the flask was put into a 4◦C water bath (to condense the vapor), where 193
mg of the compound was recovered. Patm = 760 torr. Determine the molar mass of the compound.
[10 points]
Molar mass =
n=
=
= 4.19
molar mass =
mole unknown
= 46.01
4. A 250. mL sample of gas at 25◦C and 700 torr was cooled to 4◦C and the volume reduced to
100. mL. What is the new pressure in the container ? [10 points]
=
=
P2 = 1627 torr