Download 10 TEST 2 (of 3)

Instructor: Dr. Daniel Short
Student: __________________________
/10
TEST 2 (of 3)
Show all of your work. Students should use significant figures and express their answers
in scientific notation.
1.
Write a complete balanced equation to show the reaction between sodium hydroxide and
hydrochloric acid. Include state symbols.
2.
(a) Describe how you would accurately prepare a 1.00 L solution of 0.160 mol/L sodium
hydroxide solution from solid sodium hydroxide (molar mass = 39.99 g /mol) and DI
water.
(b) 15.42 mL of the 0.160 M NaOH was required to reach the end-point in a titration with
25.00 mL of analyte HCl. Calculate the molarity of the HCl to 3 significant figures.
3.
Balance the following reactions and then write a balanced NET IONIC equation for them:
(a) AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)
(b) NaOH(aq) + HNO3(aq) → H2O(l) + NaNO3(aq)
(c) K2SO4(aq) + CaI2(aq) → CaSO4(s) + KI(aq)
(d) HNO3(aq) + CaCO3(s) → Ca(NO3)2(aq) + H2O(l) + CO2(g)
Instructor: Dr. Daniel Short
4.
Student: __________________________
Fe2O3(s) + 2Al(s)  2Fe(s) + Al2O3(s)
(a) Assign oxidation numbers to the reactants in the above reaction.
(b) Identify the oxidizing agent and reducing agent.
(c) Name this reaction.
5.
The following image represents a sample of gas at a pressure of 1 atm, a volume of 1 L,
and a temperature of 25 ºC. Draw a similar picture showing what would happen if the
volume were reduced to 0.5 L and the temperature increased to 250 ºC. What would the
new pressure be?
/10
Instructor: Dr. Daniel Short
Student: __________________________
6.
Use the ideal gas law (PV = nRT) to calculate the ideal gas law constant R at standard
temperature and pressure (273 K, 1.00 atm) assuming a molar volume of 22.4 L.
7.
Automobile air bags inflate following a serious impact. The impact triggers the following
chemical reaction:
/10
2NaN3(s) → 2Na(s) + 3N2(g)
If an automobile air bag has a volume of 11.8 L, how many moles of N2 does this equal?
(b) According to the stoichiometry 3 moles of N2 are produced for every 2 moles of NaN3.
So the number of moles of NaN3 required would be 2/3 times the amount in moles of N2.
What mass of NaN3 (in g) is required to fully inflate the air bag upon impact? (Assume
STP conditions).
Instructor: Dr. Daniel Short
8.
Student: __________________________
/10
Complete the following using the words ENDOTHERMIC, ENTHALPY, EXOTHERMIC
(a) The heat evolved in a chemical reaction at constant pressure is called the change in
__________________ for the reaction (ΔH). In an ______________ reaction ΔH is
positive, in an _______________ reaction ΔH Is negative.
(b) Hess’s Law: The change in ______________ for a stepwise process is the sum of the
changes of the steps.
9.
Calculate ΔHºrxn for the following reaction:
Fe2O3(s) + 3CO(g)  2Fe(s) + 3CO2(g)
Use the following reactions and given ΔH’s.
10.
2Fe(s) + 3/2O2(g)  Fe2O3(s)
ΔH = -824.2 kJ/mol
CO(g) + 1/2O2(g)  CO2(g)
ΔH = -282.7 kJ/mol
Write an equation for the formation of NaCl from its elements in their standard states.
Include the value of ΔHºf.
Instructor: Dr. Daniel Short
Student: __________________________
/10
BONUS:
During photosynthesis, plants use energy from sunlight to form glucose (C6H12O6) and
oxygen from carbon dioxide and water. Write a balanced equation for photosynthesis and
calculate ΔHºrxn.
Equations:
ΔHºrxn = Σ np ΔHºf (products) – Σ nr ΔHºf (reactants)
Instructor: Dr. Daniel Short
Student: __________________________
/10