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CHEM

NOTE: Show your calculation set-up, and write all values with the correct units, the correct number of significant figures, and in scientific notation form.

1. It is found that 1.431 g of element X contains 7.509 × 1021 atoms. The atomic mass of X is ??? How many protons does it contain?

2. A compound containing only carbon, hydrogen, and oxygen is subjected to elemental analysis. Upon complete combustion, a 0.4266-g sample of the compound produced 0.5518 g of CO2 and 0.2259 g of H2O. What is the empirical formula of the compound?

3. SO2 reacts with H2S as follows:

2H2S + SO2 → 3S + 2H2O

When 7.50 g of H2S reacts with 12.75 g of SO2, which is the limiting reagent and what is theoretical yield?

4. Write the complete ionic and net ionic equations for following reaction.

Ca(NO3)2(aq) + Na2CO3 (aq) → ???

5. Classify the following reactions as combination, decomposition, gas forming, displacement, acid-base, precipitation, oxidation-reduction, combustion. You should specify all of the reaction types that are applicable for each reaction:

a. Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)

b. Pb(ClO4)2(aq) + 2 KI(aq) → PbI2(s) + 2 KClO4(aq)

c. CaCO3(s) → CO2(g) + CaO(s)

d. 2HCl(aq) + O2 (g) → Cl2 (g) + H2O(l)

e. 2H2 (g) + O2 (g) → 2H2O(l)

f. 4Fe(s) + 3O2(g) → 2Fe2O3(s)

g. H2SO4(aq) + Ca(OH)2(s) → CaSO4(aq) + 2H2O(aq)

6. How many mLs of 0.560M NiCl2 (FW=129.606) solution are required to react with 15.00 mL of 0.808M AgC2H3O2 (FW=166.912) solution?

2AgC2H3O2 (aq) + NiCl2(aq) → 2AgCl(s) + Ni(C2H3O2)2 (aq)

7. A mixture of He and O2 is placed in a 4.00 L flask at 32 (C. The partial pressure of the He is 2.7 atm and the partial pressure of the O2 is 1.4 atm. What is the mole fraction of O2?

8. Balance the following reaction. Which compound is the oxidizing agent in the reaction below? Which is reducing agent? Show oxidation # and change in oxidation number for each element that changes?

Copper reacts with nitric acid to produce copper(II) nitrate, nitrogen dioxide gas, and water.

____Cu(s) + ___HNO3(aq) → ___Cu(NO3)2(aq) + ___NO2(g) + ___ H2O