Answer to Question #206034 in Chemistry for marianna

Question

Potassium nitrate reacts with carbonic acid to produce potassium carbonate and nitric acid. A chemist adds 15.15 g of potassium nitrate to 0.228 mol of carbonic acid, and gets 8.45 g potassium carbonate. Write a balanced chemical equation, including all the states of matter.  Determine the limiting reactant and the amount of potassium carbonate (in grams) produced. What is the theoretical yield of potassium carbonate? Determine the percent yield of potassium carbonate in this reaction

Answer 1

2KNO₃ + H₂CO₃ = K₂CO₃ + 2HNO₃

According to the equation, n (KNO₃) = 2 x n (H₂CO₃) = 2 x n (K₂CO₃)

n = m / M

M (KNO₃) = 101.1 g/mol

M (H₂CO₃) = 62.03 g/mol

M (K₂CO₃) = 138.2 g/mol

n (K₂CO₃) = 8.45 / 138.2 = 0.061 mol

n (KNO₃)_available = 15.15 / 101.1 = 0.15 mol

n (H₂CO₃) = 0.228 mol

The required amount of n (KNO₃) = 2 x n (H₂CO₃) = 2 x 0.228 = 0.456 mol. This is more than the available amount (0.15 mol). That is why KNO₃ is the limiting reactant. Due to this, the anticipated amount of K₂CO₃ is:

n (K₂CO₃) = 1/2 x n (KNO₃) = 0.15 /2 = 0.075 mol

m (K₂CO₃) = n x M = 0.075 x 138.2 = 10.365 g

% (K₂CO₃) = 8.45 / 10.365 x 100 = 81.5%