# Calculate the mass of calcium that can react with hydrochloric acid of 150 g with a mass fraction of HCl 7.3%.

Given:

m (HCl) = 150 g

w% (HCl) = 7.3%

To find:

m (Ca) -?

Solution:

Ca + 2HCl = CaCl2 + H2, – we solve the problem based on the composed reaction equation:

1) Find the mass of acid in solution:

m (HCl) = 150 g * 0.073 = 10.95 g

2) Find the amount of acid:

n (HCl) = m: M = 10.95 g: 36.5 g / mol = 0.3 mol

3) We compose a logical expression:

If 1 mol of Ca requires 2 mol of HCl,

then x mol Ca requires 0.3 mol HCl,

then x = 0.15 mol.

4) Find the mass of calcium required for the reaction to proceed:

m (Ca) = n * M = 0.15 mol * 40 g / mol = 6 g.

Answer: m (Ca) = 6 g.

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