Answer to Question #161670 in Chemistry for Fruitful Jaanai Uranta

Question

Calculate the % sodium in a 0.721 g detergent sample. 

Final yield is 0.320 g NaP2O4

Answer 1

The mass of sodium in 0.320 g of NaP₂O₄ is the number of the moles of NaP₂O₄ times the molar mass of sodium:

$n(NaP_2O_4) = n(Na)$

$n(NaP_2O_4) = \frac{m(NaP_2O_4) }{M(NaP_2O_4) } = \frac{0.721 }{148.93 } = 0.00484$ mol.

$m(Na) = n(Na) ·M(Na) = 0.00484·22.99$

$m(Na) = 0.111$ g.

The mass percentage of the sodium in the sample is:

$w = \frac{m(Na)}{m(sample)} ·100\%= \frac{0.111}{0.721} ·100\% = 15.4\%$ .

Answer: the % sodium in the detergent sample is 15.4%.