Question

What is the molarity of a hydrochloric acid solution, HCl (aq), if 30.00 mL of the solution is required to completely react with 25.00 mL of a 0.200 M magnesium hydroxide solution, Mg(OH)2 (aq)? Be sure to write out the balanced chemical reaction between these two compounds.

Answer 1

0.333 M

Step-by-step explanation:

Step 1: Write the balanced equation

2 HCl(aq) + Mg(OH)₂(aq) = MgCl₂(aq) + 2 H₂O(l)

Step 2: Calculate the reacting moles of Mg(OH)₂

25.00 mL of a 0.200 M magnesium hydroxide react. The reacting moles of Mg(OH)₂ are:

`25.00 * 10^(-3) L * (0.200mol)/(L) = 5.00 * 10^(-3) mol`

Step 3: Calculate the reacting moles of HCl

The molar ratio of HCl(aq) to Mg(OH)₂ is 2:1. The reacting moles of HCl are:

`5.00 * 10^(-3) molMg(OH)_2 * (2mol)/(1molMg(OH)_2) =1.00 * 10^(-2)molHCl`

Step 4: Calculate the molarity of HCl

`(1.00 * 10^(-2)mol)/(30.00 * 10^(-3)L) = 0.333 M`