Question

The available
nitrogen in a urea
sample is found to
be 45% (by weight).
Find the actual urea
content in 560 g of
the sample.
252 g
504 g
280 g
540 g

Answer 1

Answer:

Here we have to assume that the impurities in urea sample do not contain nitrogen. Otherwise this problem cannot be solved.

Lets take X grams of sample.

Amount of N = 42 X/100

% of N in Urea is 28/60=7/15

(Mol. Wt of N/Mol. Wt of Urea)

Therefore amount of urea in sample is= 42 X/100 ÷ (7/15) = 0.9X

Thus % of Urea is 0.9X/X ×100 = 90%.