The percentage of phosphourus in a detergent product may be determined by sample treatment including the precipitation of magnesium ammonium phosphate MgNH4PO4*6H2O (MW=245.41), using an excess of both magnesium and ammonium ions. The separated ans washed precipitate is then heated strongly to decompose it to magnesium pyrophosphate Mg2P2O7 (MW=222.57), which is weighted. If a 5.00 g sample of a detergent yielded 0.225 g of the weighing form, calculate the percent of phosphorus (MW=30.97) in the sample.

Question

The percentage of phosphourus in a detergent product may be determined by sample treatment including the precipitation of magnesium ammonium phosphate MgNH4PO4*6H2O (MW=245.41), using an excess of both magnesium and ammonium ions. The separated ans washed precipitate is then heated strongly to decompose it to magnesium pyrophosphate Mg2P2O7 (MW=222.57), which is weighted. If a 5.00 g sample of a detergent yielded 0.225 g of the weighing form, calculate the percent of phosphorus (MW=30.97) in the sample.

Thanks for any help/

Determine the percent composition of P in Mg2P2O7 from the formula.
Then, the mass of P is .225 x that percentage.

percent P in detergent= 100*massP/5.00

check my thinking.

I'm confused in determing the percent composition of P in Mg2P2O7. I'm not quite sure what formula to use.

Answer 1

To determine the percent composition of phosphorus (P) in Mg2P2O7, you need to calculate the molar mass of Mg2P2O7 and find the molar mass of phosphorus in it. Then, you can calculate the percentage of phosphorus in the compound.

The molar mass of Mg2P2O7 can be calculated by multiplying the atomic masses of each element and their respective subscripts in the compound:

Molar mass of Mg2P2O7 = (2 x atomic mass of Mg) + (2 x atomic mass of P) + (7 x atomic mass of O)

= (2 x 24.31) + (2 x atomic mass of P) + (7 x 16.00)

= 48.62 + (2 x atomic mass of P) + 112.00

= (2 x atomic mass of P) + 160.62

Now, you know that the molar mass of P (phosphorus) is 30.97 g/mol.

Therefore, the percent composition of phosphorus in Mg2P2O7 can be calculated using the following formula:

Percent composition of P = (atomic mass of P / molar mass of Mg2P2O7) x 100

= (30.97 / ((2 x atomic mass of P) + 160.62)) x 100

Now, you can substitute the value of percent composition of P in the detergent formula to find the mass of P.

Mass of P = (percent P in detergent / 100) x 5.00 g

Finally, you can calculate the percentage of phosphorus (P) in the detergent sample using the following formula:

Percent of phosphorus in the sample = (mass of P / 5.00) x 100

I hope this explanation helps you in understanding how to determine the percent composition of P in Mg2P2O7 and calculate the percentage of phosphorus in the detergent sample. Let me know if you have any further questions!