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# Redox, Oxidation Numbers, Limiting Reagent, Yield Problems

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1. One of the steps in the commercial process of converting ammonia to nitric acid is the conversion of NH3 into NO:
4NH3(g) + 5O2(g) ---> 4NO(g) + 6H2O(g)

In a certain experiment, 2.25 g of NH3 reacts with 3.75 g of O2.
a) Which is the limiting reactant?
b) How many grams of NO form?
c) How many grams of the excess reactant remain after the limiting reactant is completely consumed?

2. Tartaric acid, H2C4H4O6, has two acidic hydrogens (this acid is often present in wines and precipitates from solution as the wine ages). A solution containing an unknown concentration of the acid is titrated with NaOH. It requires 22.62 mL of 0.2000M NaOH solution to titrate both acidic protons in 40.00 mL of tartaric acid solution. Write a balanced net ionic equation for the neutralization reaction and calculate the molarity of the tartaric acid solution.

3. Glycerol, C3H8O3, is a substance used extensively in the manufacture of cosmetics, foodstuffs, antifreeze, and plastics. Glycerol is a water-soluble liquid with a density of 1.2656 g/mL at 15oC. Calculate the molarity of a solution of glycerol made by dissolving 50.000 mL of glycerol at 15oC in enough water to make 250.00 mL of solution.

4. A solution is made by mixing 50.0 mL of 6.00 M HCl, 100.0 mL of 1.00 M HCl, and enough water to make 250.0 mL of solution. What is the molarity of HCl in the final solution?

5. Balance each of the following redox reactions

a) Cr2O72-(aq) + CH3OH(aq) ----> HCO2H(aq) + Cr3+(aq) (Acidic Sol'n)
b) H2O2(aq) + ClO2(aq) ----> ClO2-(aq) + O2(g) (Basic Sol'n)

6. Determine the oxidation number for the indicated element in each of the following compounds:
a. Ti in TiO2
b. Sn in SnCl3-
c. C in C2O42-
d. N in N2H4
e. N in HNO2
f. Cr in Cr2O72-