Calculate the mass fraction of NH3 KNO3 NA3PO4.

To calculate the mass fraction of an individual element that is part of a substance, we use the formula:

w% (element) = Mr (element): Mr (substance) * 100%.

Using this formula, we find the mass fraction of elements in the following compounds:

a) NH3:

w% (N) = 14: 17 * 100% = 82.3%,

then the share of hydrogen accounts for 100% – 82.3% = 17.7%.

b) KNO3:

w% (K) = 39: 101 * 100% = 38.6%

w% (N) = 14: 101 * 100% = 13.9%,

then oxygen accounts for 100% – (38.6% + 13.9%) = 100% – 52.5% = 47.5%.

c) Na3PO4:

w% (Na) = (23 * 3): 164 * 100% = 69: 164 * 100% = 42%

w% (P) = 31: 164 * 100% = 19%,

then oxygen accounts for 100% – (42% + 19%) = 100% – 61% = 39%.