A compound has the formula Mg 3 X 2 . If1.87g of X combines with 4.86 g of magne

Question

A compound has the formula Mg3X2. If1.87g of X combines with 4.86 g of magnesium, what is the atomicweight of X? a. 7.0 b. 14.0 c. 21.0 d. 28.0 e. 32.0
This question was already on the website. The person who awnswer it said that the answer was 6.2 gm. However, I know the answer is b. 14. Can you explain? Thanks A compound has the formula Mg3X2. If1.87g of X combines with 4.86 g of magnesium, what is the atomicweight of X? a. 7.0 b. 14.0 c. 21.0 d. 28.0 e. 32.0
This question was already on the website. The person who awnswer it said that the answer was 6.2 gm. However, I know the answer is b. 14. Can you explain? Thanks

Explanation / Answer

The answer is 6.15 gms not 14

3 atoms Mg combine with 2 atoms of X

=>1 atom X combines with 3/2 atoms of Mg

No.of moles of Mg = 4.86/24 mol = 0.2025 mol

=>1.87 gm X = 3/2 x 0.2025 mol = 0.30375 mol

molar mass of X = 6.15 gms

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