Question

Calculate which of the following calcium nitrate or ammonium sulphate has a higher % of nitrogen. $ [Ca = 40,O = 16,S = 32,N = 14] $ .

Answer 1

Hint :As we know that a percentage is a number or ration which is expressed as a fraction of $ 100 $ .. In this question we have to find that which has the higher percentage i.e. calcium nitrate or ammonium nitrate . We can find this by the formula percentage by weight $ = \dfrac{a}{b} \times 100 $ , where $ a = weight $ and $ b = $ total weight.

Complete Step By Step Answer:
We know that the chemical formula of calcium nitrate is $ Ca{(N{O_3})_2} $ .
The molecular weight of nitrogen is $ 14g $ and we can see that the molecular weight of nitrogen in $ Ca{(N{O_3})_2} $ is twice i.e. $ 2 \times 14g $ $ = 28g $ .
Also we know that the molar mass or weight of $ Ca{(N{O_3})_2} $ is $ 164g $ .
Now by putting the values in the formula we can calculate the percentage of weight by the formula $ = \dfrac{{28}}{{164}} \times 100 = 17.073\% $ .
Now we will calculate the weight of ammonium sulphate by the same method as above:
We know that the chemical formula of ammonium sulphate is $ {(N{H_4})_2}S{O_4} $ .
The molecular weight of nitrogen is $ 14g $ and we can see that the molecular weight of nitrogen in $ {(N{H_4})_2}S{O_4} $ . is twice i.e. $ 2 \times 14g $ $ = 28g $ .
Also we know that the molar mass or weight of $ {(N{H_4})_2}S{O_4} $ . is $ 132g $ .
Now by putting the values in the formula we can calculate the percentage of weight by the formula $ = \dfrac{{28}}{{132}} \times 100 = 21.21\% $ .
Hence we can see that the percentage of nitrogen in ammonium sulphate is higher than in calcium nitrate.

Note :
Before solving this kind of question we should be fully aware of chemical formulas and should remember the molecular weight of nitrogen. We should also avoid calculation mistakes while solving and applying the formulas.