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Chemistry 1 Exam 1 S October 2, 2009
Name _________________________ Student ID # ______________ Section __________
It is critically important that you show clear and logical responses. Be sure to use proper chemical equations, units, and show calculations quantitatively.
1. (18 pts) Assign whether the species in water would be an acid, base, or of neutral pH; a strong, weak, or non-electrolyte; and write the oxidation number of the specified element(s) in the compound for each compound below. Electrolyte Oxidation number acid strong a) CaO base weak Ca _______ neutral non-
acid strong b) N 2 O 3 base weak N _______ neutral non-
acid strong C _______ c) CH 3 OH base weak neutral non- O _______
acid strong P _______ d) H 2 PO 4 –^ base weak neutral non- O _______
acid strong Al _______ e) Al(ClO 2 ) 3 base weak neutral non- Cl _______
2. (18 pts) Household bleach is a 5.00% by mass aqueous sodium hypochlorite solution. a) What is the molar concentration of household bleach (d = 1.00 g/mL)?
b) Bleach is diluted by adding 250mL into 10.0L for disinfection of potable water storage containers. What is the molar concentration used for disinfection?
3. (24 pts) Piperazine is a compound that is used medicinally to cure nematode infections. Piperazine contains carbon hydrogen and nitrogen. a) Of what type is a combustion reaction (circle one)? acid-base precipitation redox b) A 25.05mg sample was analyzed by combustion, which produced 51.18 mg of carbon dioxide, 26.17 mg of water. What is the empirical formula of piperazine?
b) The same sample of piperazine was analyzed by mass spectroscopy. The molecular mass of piperazine is 86.14 g/mol. Find the molecular formula of piperazine.
5. (25 pts) If 300.0 mL of a 4.00 x 10-3^ M aqueous HCl solution is added to 175.0mL of a 4. x 10-3^ M aqueous sodium oxide solution:
a) What type of reaction is occurring (circle one) acid-base precipitation redox
b) Write a balanced chemical equation for the reaction of sodium oxide with water that occurs upon dissolution.
c) Write the net ionic chemical equation for the reaction that occurs upon mixing the aqueous sodium oxide solution with the aqueous sulfuric acid solution.
d) What is the pH of the resulting solution, after mixing?
e) The resulting solution is (circle one): acidic neutral alkaline
6. (20 pts) Determine the oxidation and reduction atom and charge-balanced half reactions and use the half reaction method to balance the redox reaction according to the following skeletal equation:
Fe (s) + H 2 CrO 4 (aq) FeO (s) + Cr3+^ (aq)
Oxidation half reaction (atom and charge balanced):
Reduction half reaction:
Summation of half reactions, cancellation, final balanced reaction:
