Chemistry Homework

Question

A 15.0 mL solution of Sr(OH)₂ is neutralized with 26.9 mL of 0.350 M HCl. What is the concentration of the original Sr(OH)₂ solution?

Answer 1

Write the balanced equation:

Sr(OH)₂ + 2HCl ==> 2H₂O + SrCl₂

Calculate moles of HCl used:

26.9 ml x 1 L / 1000 ml x 0.350 mol / L = 0.009415 moles HCl

Use the stoichiometry of the balanced equation for calculate moles of Sr(OH)₂ present:

0.009415 mols HCl x 1 mol Sr(OH)₂ / 2 mols HCl = 0.004708 mols Sr(OH)₂

Finally, divide by the volume of Sr(OH)₂ to get concentration:

0.004708 mols / 15.0 ml x 1000 ml / L = 0.314 mols / liter = 0.314 M Sr(OH)₂