Question

A sample of ethane has the same mass as 10.0 millions molecules of methane. How many $C_2{H}_6$ molecules does the sample contain?

Answer 1

Mass of $1$ molecule of $C{H}_4=\frac{16}{6.022\times {10}^{23}}g$

Mass of $10$ million molecule of $C{H}_4=\frac{16}{6.022\times {10}^{23}}\times {10}^{7}g$

With ethane,

$\frac{16}{6.022\times {10}^{23}}\times {10}^7=\frac{16}{6.022\times {10}^{23}}\times X$

$x=5.3203\times {10}^6$ molecules