A white powder, of mass 2g, consists of a mixture of N-phenylethanamide and its isomer 4-methylbenzamide. On treatment of the powder with hot NaOH, a volume of NH3 is released measuring 150cm3 at 100 000Pa and 20degrees C.
Find the percentage by mass of 4-methylbenzamide in the mixture and explain your reasoning.How to calculate percentage by mass?
First, you need to calc the molecular weight of 4-methylbenzene.
Write out the chemical equation.
Calculate the mol of NH3 released from its volume.
Mol = g/molecular weight or volume/22.4
Then, calculate how many moles of 4-methybenzene is needed to give out the correspond mole of NH3.
Finally, convert the mole of 4-methylbenzene back to g, and convert it to % by divided with 2g x 100%
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