CHEM
35
General
Chemistry
October 27, 2000
Name:
Shuns, Sol Lew
1.
A sample of 70.5 mg of
K3PO4 (MW = 212.266 g/mol) is added to 15.0 mL of 0.050 M
AgNO3, resulting in the formation of a precipitate.
a. (2 pts) Write
a balanced net ionic equation for this reaction.
3 Ag+(aq) + K3PO4(s)
® Ag3PO4(s)
+ 3 K+(aq)
b.
(2 pts) What is the limiting reactant in this reaction.
0.0705 g K3PO4
x mol K3PO4 x 3 mol AgNO3 x L
x 1000 mL =
212.266 g K3PO4 1 mol K3PO4 0.050 mol AgNO3 L
19.9
mL AgNO3
(needed)
Only 15 mL AgNO3
available, so
AgNO3 is
LIMITING REACTANT
c.
(2 pts) Calculate the mass (g) of precipitate formed in this
reaction
0.0150 L AgNO3 x 0.050 mol AgNO3 x 1 mol Ag3PO4
x 418.576 g Ag3PO4
=
L
3 mol AgNO3 mol
Ag3PO4
=
0.10464 g Ag3PO4
= 0.10 g Ag3PO4
2. (2 pts each) Each of the following reactions produces a gas as one of its products.
For each reaction, write a balanced reaction equation.
a.
CaCO3(s)
+ HNO3(aq) ® products
CaCO3(s) + 2 HNO3(aq)
® Ca(NO3)2(aq)
+ H2O(l) + CO2(g)
b.
Cu(s) +
HNO3(aq) ® products
Cu(s) + 2 HNO3(aq)
® Cu(NO3)2(aq)
+ H2(g)