Answer
a. Mass of calcium atom = 6.656 x $10^{-23}$ g
b. Mass of ethanol molecule = 7.645 g x $10^{-23}$ g
Work Step by Step
a. The molar mass of Ca is 40.07 g/mol. If we divide the mass of one mol Ca with Avogadro's number, we can find the mass of 1 calcium atom.
Mass of calcium atom = $\frac{40.07 g}{6.02 * 10^{23}}$
Mass of calcium atom = 6.656 x $10^{-23}$ g
b. First we find the molar mass of ethanol $C_{2}$$H_{5}$OH :
Molar mass of $C_{2}$$H_{5}$OH = 2 x AM C + 6
AM H + AM O
Molar mass of $C_{2}$$H_{5}$OH =2 x 12.011 + 6 x 1.00 + 15.999 = 46.021 g
If we divide the mass of one mol $C_{2}$$H_{5}$OH with Avogadro's number, we can find the mass of 1 ethanol molecule.
Mass of ethanol molecule = $\frac{46.021 g}{6.02 * 10^{23}}$
Mass of ethanol molecule = 7.645 g x $10^{-23}$ g
