3. A volume of 90 mL of 0.2 M HBr neutralizes
a 60 mL sample of NaOH solution. What is
the concentration of the NaOH solution?

0.3M

Explanation:

Step 1:

Data obtained from the question. This include the followingb:

Volume of acid (Va) = 90mL

Concentration of acid (Ca) = 0.2M

Volume of base (Vb) = 60mL

Concentration of base (Cb) =?

Step 2:

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

HBr + NaOH —> NaBr + H2O

From the balanced equation above,

The mole ratio of the acid (nA) = 1

The mole ratio of the base (nB) = 1

Step 3:

Determination of the concentration of the base, NaOH.

The concentration of the base can be obtained as follow:

CaVa /CbVb = nA/nB

0.2 x 90 / Cb x 60 = 1

Cross multiply

Cb x 60 = 0.2 x 90

Divide both side by 60

Cb = 0.2 x 90 /60

Cb = 0.3M

Therefore, the concentration of the base, NaOH is 0.3M

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