What is the concentration of a solution containing 2g of NaOH in 100cm 3 of solution? [Na = 23, O = 16, H = 1]

Correct Answer is : 0.50 mol dm-3

Correct Answer is : 0.50 mol dm-3

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JAMB Chemistry 2011 Paper

Question : 1

Total: 47

[Na = 23, O = 16, H = 1]

Solution:

Concept:

Concentration in mol dm⁻³ is moles of solute divided by volume in dm³.

Explanation:

Molar mass of NaOH:

M_r = 23 + 16 + 1 = 40 \, \text{g mol}^{-1}

Moles of NaOH:

\text{moles} = \frac{2}{40} = 0.05 \, \text{mol}

Convert volume:

100 \, \text{cm}^3 = 0.1 \, \text{dm}^3

Concentration:

\text{Concentration} = \frac{0.05}{0.1} = 0.50 \, \text{mol dm}^{-3}

Answer:

0.50 mol dm⁻³, which is option B.

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