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Atoms And Molecules

Question
CBSEENSC9005066

Calculate the mass in grams of the following:

(i) One mole of sulphuric acid (H2SO4).

(ii) 0.5 mole of aluminium sulphate Al2(SO4)3.

(iii) 0.05 mole of ammonia (NH3).

(iv) 0.7 mole of hydrogen chloride (HCl).

Solution

left parenthesis straight i right parenthesis space 1 space mole space of space straight H subscript 2 SO subscript 4 space equals space 2 plus 32 plus 64 space equals space 98 space straight g
space space space molecular space mass space equals 98 straight g

left parenthesis ii right parenthesis space 1 space mole space of space Al subscript 2 left parenthesis SO subscript 4 right parenthesis space equals space 2 space cross times 27 space plus space left parenthesis 32 plus 64 right parenthesis subscript 3 space equals space 342 space straight g space space
space space space space space space molecular space mass space equals 342 straight g
therefore space 0.5 space mole space of space Al subscript 2 left parenthesis SO subscript 4 right parenthesis subscript 3 space equals space fraction numerator 342 space cross times space 5 over denominator 10 end fraction space equals space 171 space straight g

left parenthesis iii right parenthesis space 1 space mole space of space NH subscript 3 space equals space 14 plus 3 space equals space 17 space straight g
therefore space 0.05 space mole space of space NH subscript 3 space equals space 17 space cross times space 0.05 space equals space 0.85 space straight g

left parenthesis iv right parenthesis space space 1 space mole space of space HCl space equals space 1 space plus space 35.5 space equals space 36.5 space straight g
space space space space space space space 0.7 space mole space of space HCl space equals space 0.7 space cross times 36.5 space equals space 25.55 space straight g space