Answer:
4.041 moles C₂H₆
Step-by-step explanation:
To convert from grams to moles, you first need to determine the molar mass of C₂H₆. The molar mass is the combination of the atomic masses times the quantity of each element present in the molecule. The atomic masses usually be found on the periodic table. They represent how much the element weighs per one mole.
Carbon (C) Atomic Mass: 12.01 g/mol
Hydrogen (H) Atomic Mass: 1.008 g/mol
Molar Mass (C₂H₆): 2(12.01 g/mol) + 6(1.008 g/mol)
Molar Mass (C₂H₆): 30.068 g/mol
Now that you have the molar mass, you can multiply this ratio to the given value. Keep in mind that in order to go from grams to moles, the numerical value should be place in the denominator of the molar mass ratio. This allows for the cancellation of the unit 'grams'. The final answer should have 4 significant figures because the given value also has 4 sig figs.
121.5 grams C₂H₆ 1 mole
-------------------------- x ------------------------ = 4.041 moles C₂H₆
30.068 grams