Question

3. Identify the oxidized and reduced reactants in the following redox reactions:

a.

Ca(s) + 2H2O(l) Ca(OH)2(aq) + H2(g)

b.

CH4(s) + 2 O2(g)    2 H2O(g) + CO2(g)

c.

2 SnCl2(aq) + 2 Al(s)     2AlCl3(aq) + 3 Sn(s)

4. A 10.000 g sample of ascorbic acid was analyzed and found to contain 4.091 g of carbon, 0.458 g of hydrogen and the remainder is oxygen. The molar mass of ascorbic acid is 176.1 g/mol.

a. Determine the empirical formula of ascorbic acid.

b. Determine the molecular formula of ascorbic acid.

5. Consider the decomposition of solid sodium azide, NaN3, into sodium metal and nitrogen gas. What is the percent yield if 50.0 g of sodium azide produced 29.7 g of nitrogen?

Answer 1

Ans 3 :

a) The oxidation number of Ca has increased from 0 to +2 in products, so Ca is oxidised.

Hydrogen has +2 in reactants and 0 in products , therefore hydrogen has got reduced.

b) carbon has -4 oxidation state in reactant , which increased to +4 in products , so carbon got oxidised.

Oxygen has 0 oxidation state in reactant which reduces to -2 in products , so oxygen got reduced.

c) Sn has +2 oxidation state in reactant , which reduced to 0 in product side , so Sn got reduced.

Al has 0 oxidation state in reactant side , which increased to +3 in product side , so Al got oxidised.