What is the concentration of an unknown Mg (OH) 2 solution if it took an average of 15.4mL of

0.100M HCl solution to neutralize 10.0mL of the Mg (OH) 2 solution?

Your answer

0.077M

Explanation:

Step 1:

The balanced equation for the reaction. This is given below:

2HCl + Mg (OH) 2 - > MgCl2 + 2H2O

From the balanced equation above,

The mole ratio of the acid (nA) = 2

The mole ratio of the base (nB) = 1

Step 2:

Data obtained from the question.

Concentration of base Cb = ... ?

Volume of base (Vb) = 10mL

Concentration of acid (Ca) = 0.1M

Volume of acid (Va) = 15.4mL

Step 3:

Determination of the concentration of the base, Mg (OH) 2.

The concentration of the base can be obtained as follow:

CaVa/CbVb = nA/nB

0.1 x 15.4 / Cb x 10 = 2/1

Cross multiply to express in linear form

Cb x 10 x 2 = 0.1 x 15.4

Divide both side by 10 x 2

Cb = (0.1 x 15.4) / (10 x 2)

Cb = 0.077M

Therefore, the concentration of the base, Mg (OH) 2 is 0.077M