How many molecules of ethane (C2H6) are present in 0.628 g of C2H6? Round your answer to three significant digits.

Answer 1

To determine the number of molecules, we need to use Avogadro's number (6.022 x 10^23 molecules/mol) and the molar mass of ethane (30.07 g/mol).

First, we calculate the number of moles of ethane:
moles = mass / molar mass
moles = 0.628 g / 30.07 g/mol = 0.0209 mol

Next, we convert moles to molecules using Avogadro's number:
molecules = moles * Avogadro's number
molecules = 0.0209 mol * 6.022 x 10^23 molecules/mol = 1.257 x 10^22 molecules

Rounded to three significant digits, there are 1.26 x 10^22 molecules of ethane in 0.628 g.