Answer:
It's not entirely clear whether your question is asking for the percent composition of phosphorus in the substance or the percent composition of all the elements in the substance that contains phosphorus. In either case, the percent composition of phosphorus in this substance is 16.9%.
The percent composition of all the elements in the substance is 48.1% nickel, 16.9% phosphorus, and 35.0% oxygen.
Step-by-step explanation:
The percent composition of a substance in a sample can be found by dividing the mass of each element present in the sample by the total mass of the sample, and then multiplying by 100%.
To find the percent composition of the substance, we compute the total mass of the sample by adding the masses of all the elements present:
7.22 g + 2.53 g + 5.25 g = 15 g
Next, we divide the mass of each element by the total mass of the sample (15 g) and multiply by 100%.
Nickel: (7.22 g / 15 g) * 100% = 48.13%
Phosphorus: (2.53 g / 15 g) * 100% = 16.87%
Oxygen: (5.25 g / 15 g) * 100% = 35.00%
Given to three significant figures, the percent composition of the substance is: 48.1% nickel, 16.9% phosphorus and 35.0% oxygen.