Question

7. Solid sodium oxide is synthesized from it elements in a reaction that is 45.6% efficient. How many grams of sulfur must be used in the reaction in order to produce 350.0 g of the product? 8. A 78.91 g sample of ethane, C,H, is completely oxidized in a reaction with 94.21 g of oxygen. What mass of products (in grams) are produced in the reaction? 9. 5.43 x 1023 formula units of sodium phosphate are reacted with 8.32 x 1024 formula units of copper(II) sulfate. Both reactants are in solution. How many grams of precipitate are produced in the reaction? Write the net ionic equation for this reaction. 10. What mass of precipitate is formed if 12.4 mL of a 1.25 M ammonium phosphate solution is added to a solution containing excess iron(II) sulfate?

Answer 1

Question 7.

Reaction: S + O₂ ----> SO₂

The mass of SO2 produced = 350 g = 350 g/(64 g/mol) = 5.46875 mol

Here, the reaction is 46% efficient.

i.e. (no. of moles of product/no. of moles of reactant)*100 = 46

i.e. (5.46875 mol/no. of moles of S) = 0.46

i.e. The no. of moles of S = 5.46875 mol/0.46 = 11.888587 mol

Therefore, the required mass of sulfur (S) = 11.888587 mol * 32 g/mol = 380.435 g