Chem 1020
Take-home quiz (Quiz 2)
Fall 2004
Complete the following questions on your own paper. Show all your work and place
boxes around your answers. You may work together, but hand in your own copy. This
take-home quiz is due Monday, November 29, and is worth 15 points.
1. Solutions of sodium hypochlorite, NaClO, are sold as a bleach (such as
Chlorox).They are prepared by the reaction of chlorine with sodium hydroxide.
2NaOH(aq) + Cl2(g) → NaCl(aq) + NaClO(aq) + H2O(l)
If you have 1.23 mol of NaOH in solution and 1.47 mol of Cl2 gas available to
react, which is the limiting reactant?
1 mol NaClO
 0.615 mol NaClO
2 mol NaOH
1 mol NaClO
1.47 mol Cl 2 
 1.47 mol NaClO
1 mol Cl 2
1.23 mol NaOH 
The NaOH produces fewer moles of NaClO, so it is the limiting reactant.
How many moles of NaClO(aq) could be obtained?
The number of product which can be produced is limited by the limiting reactant.
As shown above, 0.615 mol NaClO can be produced.
2. Aspirin (acetylsalicylic acid) is prepared by heating salicylic acid, C7H6O3, with
acetic anhydride, C4H6O3. The other product is acetic acid, C2H4O2.
C7H6O3 + C4H6O3 → C9H8O4 + C2H4O2
If 2.00 g of salicylic acid is heated with 4.00 g of acetic anhydride, which is the
limiting reactant?
Molar mass C 7 H 6 O 3  138.118 g/mol
Molar mass C 4 H 6 O 3  102.088 g/mol
1 mol salicylic acid
1 mol aspirin

 .01448 mol aspirin
138.118 g salicylic acid 1 mol salicylic acid
1 mol acetic anhydride
1 mol aspirin
4.00 g acetic anhydride 

 .03918 mol aspirin
102.088 g acetic anhydride 1 mol acetic anhydride
2.00 g salicylic acid 
What is the theoretical yield (in grams) of aspirin, C9H8O4?
Molar mass C 9 H 8 O 4  180.154 g/mol
.01448 mol aspirin 
180.154 g aspirin
 2.61 g aspirin
1 mol aspirin
If the actual yield of aspirin is 1.86 g, what is the percentage yield?
% yield 
actual yield
1.86 g
 100% 
 71.3% yield
theoretical yield
2.609 g
3. Titanium, which is used to make airplane engines and frames, can be obtained from
titanium tetrachloride, which in turn is obtained from titanium dioxide by the
following process:
3TiO2(s) + 4C(s) + 6Cl2(g) → 3TiCl4(g) + 2CO2(g) + 2CO(g)
A vessel contains 4.15 g TiO2, 5.67 g C, and 6.78 g Cl2. Which is the limiting
reactant?
Molar mass TiO2 = 79.90 g/mol
Molar mass C = 12.00 g/mol
Molar mass Cl2 = 70.9 g/mol
4.15 g TiO 2 
1 mol TiO 2 3 mol TiCl 4

 0.05194 mol TiCl 4
79.90 g
3 mol TiO 2
1 mol C 3 mol TiCl 4

 0.3544 mol TiCl 4
12.00 g C
4 mol C
1 mol Cl 2 3 mol TiCl 4
6.78 g Cl 2 

 0.04781 mol TiCl 4
70.9 g Cl 2 6 mol Cl 2
5.67 g C 
Cl 2 is the limiting reactant.
What is the theoretical yield (in grams) of titanium tetrachloride?
0.04781 mol TiCl 4 
189.7 g TiCl 4
 9.07 g TiCl 4
1 mol TiCl 4