A sample of sucrose is found to contain 72.28 xx 10^21 atoms of carbon. Find the mass of the sample in grams.

A sample of sucrose is found to contain 72.28 xx 10^21 atoms of carbon

1.	A sample of sucrose is found to contain 72.28 xx 10^21 atoms of carbon. Find the mass of the sample in grams.
Answer» Solution :The MOLECULAR formula of sucrose is `C_12H_22O_11`. From this formula, it is evident that one mole of sucrose CONTAINS 12 gram atoms of carbon. The molecular mass of sucrose is`(12 xx 12.01) + (22 xx 1.008) + (11 xx 16.0) = 342.296` amu. Since, 1 gram atom of carbon contains `6.022 xx 10^(23)`atoms, the number of gram atoms CORRESPONDING to `72.28 xx 10^(21)` atoms `=(72.28 xx 10^(21))/(6.022 xx 10^(23)) = 0.1200` `therefore` The gram moles of sucrose which contain 0.12 gram atoms of carbon `=1/12 xx 0.1200 = 0.0100` `therefore` The mass of 0.0100 moles of sucrose `=0.0100 xx 342.296 = 3.423 g`