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CHM 1045 Fall 2010
Test 2
Show your work for complete (and partial) credit. Report your answers to the correct
number of significant figures, and use units where appropriate. All chemical equations
should balance; indicate phases. NA=6.022x1023
1. What is the definition of the mole?
2. What is the mass of 6.50 moles of CH3OH?
3. What mass of CaCl2 (110.99g/mol) would contain 5.00g of chlorine?
4. What mass of methane (CH4, 16.043g/mol) would contain 5.00 x 1024 H atoms?
MgCl2(aq) + 2AgNO3(aq) → 2AgCl(s) + Mg(NO3)2(aq) (Next two questions)
Compound: MgCl2
Mg(NO3)2 AgCl
AgNO3
f.w.(g/mol): 95.211
148.435
143.321
169.87
5. How many mols of MgCl2 is required to form 15.2g of AgCl?
6. What mass of MgCl2 is required to form 1.223g of AgCl?
7. In the reaction 2Mg(s) + O2(g) → 2MgO, what is the maximum mass of MgO
(40.304g/mol) that can be produced by the reaction of 25.0g of each reactant? Note:
this is a limiting reactant problem.
8. A sample of a hydrocarbon, a compound containing only carbon and hydrogen, was
combusted for elemental analysis. A 6.014mg sample of the compound produced
17.60mg of CO2 (44.01g/mol) and 10.81mg of H2O. What is the empirical formula
for the hydrocarbon?
9. Give the net ionic equation for the following equation.
H2SO4(aq) + Mg(s)
MgSO4(aq) + H2(g).
10. Give an example of an (any) acid/base reaction (balanced, phases).
11. Write a molecular equation (balanced, phases) for the reaction described: Lead(II)
nitrate solution and sodium sulfate solution are mixed. A precipitate of lead(II) sulfate
forms.
12. Write a chemical equation for the reaction that occurs when aqueous solutions of
calcium chloride and silver(I) nitrate are mixed, given the following information.
Compound
Solublility
Calcium chloride
Soluble
Calcium nitrate
Soluble
Silver(I) chloride
Insoluble
Silver(I) nitrate
Soluble
13. A sample of limestone (containing calcium carbonate, CaCO3) weighing 413mg is
treated with oxalic acid (H2C2O4) to give 472mg calcium oxalate (CaC2O4).
CaCO3(s) + H2C2O4(aq) CaC2O4(s) + CO2(g) + H2O(l). What is the percentage of
calcium carbonate in the limestone?
Compound
CaCO3
H2C2O4
CaC2O4
CO2
Formula mass 100.087g/mol
90.036g/mol
128.10g/mol
44.010g/mol
14. What is the oxidation number of each underlined atom?
S2O3-2
Na
ZnCO3
15. In the reaction 2Fe(s) + 6HCl(aq)
HNO3
2FeCl3(aq) + 3H2(g),
_______ is reduced to ________ and _______ is oxidized to _______.
16. In the activity series, magnesium is above aluminum. Predict the products of the
following reactions and balance the reactions, or write "nr" if no reaction will occur.
a) ___Al(s) + ___Mg(s) →
b) ___AlCl3(aq) + ___Mg(s) →
c) ___Al(s) + ___Mg(NO3)2 →
17. Write an oxidation half reaction. Any oxidation half reaction will do.
18. How many mols of NaOH (39.997g/mol) are in 833.4mL of .122M?
19. What volume of 1.2 x 10-3M methanol (CH3OH, 32.04g/mol) would contain 15
milligrams of methanol?
20. What volume of 0.1550M NaOH is required to completely react with 25.00mL of
0.1234M H2SO4?
H2SO4(aq) + 2NaOH(aq) → 2H2O(l) + 2NaCl