Question

1.8 g of ethane gas is used to

boil 200 cm' of water. What
is the number of molecules
of the ethane gas?
[Relative atomic mass of
C = 12 and H = 1, Avogadro
constant = 6.02 x 10^23 mol ]​

Answer 1

3.6 x 10²²molecules

Step-by-step explanation:

Given parameters:

Mass of ethane gas = 1.8g

Unknown:

number of molecules of ethane gas = ?

Solution:

To solve this problem, we first find the number of moles of ethane gas.

Molar mass of ethane, C₂H₆ = 2(12) + 6(1) = 30g/mol

Number of moles =
`(mass)/(molar mass)`

Insert the parameters and solve;

Number of moles =
`(1.8)/(30)` = 0.06mole

1 mole of a substance contains 6.02 x 10²³ molecules

0.06mole of ethane will contain 0.06 x 6.02 x 10²³ = 3.6 x 10²²molecules