Question

ERCENTAGE COMPOSITION
Calculate the percentage by weight of :a] C in carbon dioxide, b] Na in sodium carbonate, c] Al in
aluminium nitride. [C=12, O=16, H=1, Na=23, Al=27, N=14 ] [Ans.27.3% of C, 43.4% of Na, 65.85% of All
Calculate the percentage of iron in K3Fe(CN)6. [K=39, Fe=56, C=12, N=14] [Ans. 17.02% of Fe]​

Answer 1

Explanation:

percentage by weight=

total weight

weight

×100

Therefore,

(a)percentage by weight of C in carbon dioxide-

Weight of carbon in CO

2

=12g

Weight of CO

2

=44g

∴ percentage by weight =

44

12

×100=27.27%≈27%

(b)percentage by weight of Na in sodium carbonate-

Weight of sodium =23g

Weight of sodium in Na

2

CO

3

=2×23=46g

Weight of Na

2

CO

3

=106g

∴ percentage by weight =

106

46

×100=43.4%

(c)percentage by weight of Al in aluminium nitride-

Weight of aluminium in AlN=27g

Weight of AlN=41g

∴ percentage by weight =

41

27

×100=65.85%

Hence the given statement is true.