Question

Find the number of moles in 508 g of ethanol (C2H5OH).

Answer 1

To find the number of moles we start by calculating the molar mass:
M(C2H5OH) = 2*M(C) + 6*M(H) + M(O)
M(C2H5OH) = 2* 12.01 + 6* 1.008 + 16
M(C2H5OH) = 46.068g

This is mass of one mole of ethanol. Total mass of ethanol can be calculated by using formula:
m = N * M
Where:
m = total mass
N = number of moles
M = molar mass

We rearrange formula for N:
N = m / M
N = 508 / 46.068
N = 11.03

508g of ethanol contains 11.03 moles.