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Calculate the mass of the following : (i) 1 atom of sodium (ii) 10 molecules of argon (iii) 1 molecule of CO_2 (iv) 1 molecule of H_2SO_4. |
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Answer» Solution :(i) The gram atomic mass of sodium = 22.99 This mass contains `6.022 xx 10^(23)` sodium ATOMS. `therefore` Mass of one atom of sodium `=(22.99)/(6.022 xx 10^(23)) = 3.817 xx 10^(-23) g` (ii) Argon is monoatomic. Therefore, its one molecule contains only one atom. HENCE, gram molecular mass of argon = its gram atomic mass 39.95 g. This mass contains `6.022 xx 10^(23)` molecules Hence, mass of 10 molecules of argon `=(10 xx 39.95)/(6.022 xx 10^(23)) = 6.634 xx 10^(-22)g` (iii) Gram molecular mass of `CO_(2)` `=12.01 xx (2 xx 16.0) = 44.01 g` This mass contains `6.022 xx 10^(23)` molecules. Therefore, mass of one molecule of `CO_(2) = (44.01)/(6.022 xx 10^(23)) = 7.308 xx 10^(-23) g` (iv) Gram molecular mass of `H_(2)SO_(4)` `=(2 xx 1.008) + 2.06 + (4 xx 16.0) = 98.076` g This mass contains `6.022 xx 10^(23)` molecules. Therefore, mass of one molecule of `H_(2)SO_(4) = (98.076)/(6.022 xx 10^(23)) = 1.629 xx 10^(-22) g` |
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