Step-by-step explanation:
It is required the atomic masses of all elements that take part in this molecule:
MgNH4PO4.6H2O
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From the periodic table:
Mg) 24.3 u
N) 14.0 u
H) 1.00 u
P) 31.0 u
O) 16.0 u
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After that, the molecular weight is calculated as follows:
The molecular weight = 1 x 24.3 (Mg) + 1 x 14.0 (N) + 4 x 1.00 (H) + 1 x 31.0 (P) + 4 x 16.0 (O) + 6 x 2 x 1.00 (H) + 6 x 16.0 (O) = 245.3 g/mol approx.
Answer: 245.3 g/mol