Chemistry 1105 Spring 2017 Test 2
Monday, February 27, 2017
Time: 1 hour 50 minutes
Name: _________________________
Student #: _________________________
This test consists of five pages of questions and a periodic table. Please ensure that you have a
complete test and, if you do not, obtain one from me immediately. There are 32 marks
available. Good luck!
1) [6 marks] Penicillin, an antibiotic used in the treatment of infections, is 44.437 percent
carbon, 4.558 percent hydrogen, 11.516 percent nitrogen, 26.308 percent oxygen, and the
rest sulphur, all by mass.
a) What is the empirical formula of penicillin?
b) Penicillin reacts with acids according to the (balanced) equation:
Penicillin + 2HCl
products
It took 20.00 mL of 0.200 M HCl to react with a 486.5 mg sample of penicillin. What is
the molecular formula of penicillin?
2) [7 marks total] Paracetamol is the active ingredient in Tylenol. Paracetamol contains C, H,
N, and O.
a) [4 marks] A 1511.6-mg sample of paracetamol was burned, and 3520.8 mg of CO2
(44.01 g/mol), 810.9 mg of H2O (18.02 g/mol), and 460.1 mg of NO2 (46.01 g/mol)
collected. What is the empirical formula of paracetamol?
b) [3 marks] Paracetamol reacts with sodium metal according to the (balanced) equation:
2Na(s) + 2paracetamol
products
It took 459.8 mg of sodium to react with a 3023.3 mg sample of paracetamol. What is
the molecular formula of paracetamol?
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3) [5 marks] A 15.00 mL aliquot of solution A (containing NaOH) was taken and diluted to
250.0 mL to form solution B. A 25.00 mL aliquot of solution B was taken and diluted to
200.0 mL to form solution C. It took 12.50 mL of solution C to titrate a 10.00 mL aliquot of
3.00 x 10-3 M H2SO4:
2NaOH(aq) + H2SO4(aq)
Na2SO4(aq) + 2H2O(l)
What were the concentrations of NaOH in solutions A, B, and C?
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4) [2 marks] A 10.00 mL aliquot of H3C6H5O7 required 21.62 mL of 0.2116 M NaOH for
complete titration:
3NaOH(aq) + H3C6H5O7(aq)
Na3C6H5O7(aq) + 3H2O(l)
What was the [H3C6H5O7] in the aliquot?
5) [4 marks] A 928.3-mg sample of a compound of formula GaX3 was reacted with excess
Na2CO3 and 329.2 mg of Ga2(CO3)3 (319.5 g/mol) collected:
2GaX3(aq) + 3Na2CO3(aq)
Ga2(CO3)3(s) + 6NaX(aq)
What is the element, X? The reaction proceeded with 68.697 percent yield.
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6) [4 marks] A 10.00-mL aliquot of a solution of HXO4 (where X is some unknown element) has
a density of 1.05 g/mL.
a) The 10.00 mL aliquot required 36.23 mL of 0.2000 M NaOH for complete titration:
NaOH(aq) + HXO4(aq)
NaXO4(aq) + H2O(l)
What was the concentration of HXO4 in the 10.00 mL aliquot?
b) It was found that the 10.00 mL aliquot was 10.00 percent HXO4 by mass. What is the
element, X?
7) [4 marks[ How many grams of 80.0-percent pure CaCl2 (111.0 g/mol) are required to
produce 14.32 g of AgCl (143.2 g/mol)?
CaCl2(aq) + 2AgNO3(aq)
2AgCl(s) + Ca(NO3)2
Assume the reaction proceeds with a 75.0-percent yield.
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