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WAEC Chemistry 2017 Paper

Question : 7

Total: 50

\mathrm{(NH_{4})_{2}CO_{3}}

is [O=16.0, N=14.0, C=12.0, H=1.0]

Solution:

Concept:

The mass of one mole of a compound is its molar mass in grams.

Explanation:

The formula is

\mathrm{(NH_4)_2CO_3}

There are 2 nitrogen atoms, 8 hydrogen atoms, 1 carbon atom, and 3 oxygen atoms.

Molar mass

= (2 \times 14.0) + (8 \times 1.0) + 12.0 + (3 \times 16.0)

= 28.0 + 8.0 + 12.0 + 48.0

= 96.0\ \text{g}

Thus, one mole of

\mathrm{(NH_4)_2CO_3}

has a mass of

96.0\ \text{g}

Answer:

96.0\ \text{g}

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