Answer:
0.801 moles H₂CCl₂
Explanation:
To find the amount of moles, you need to multiply the given mass by the molar mass. The molar mass is a ratio describing the mass (g) per every 1 mole. The molar mass of H₂CCl₂ can be calculated by adding the atomic masses of each atom within the molecule.
When multiplying a number by the molar mass, it is important to arrange the ratio in a way that allows for the cancellation of units (moles should be in the numerator). The final answer should have 3 sig figs like the given value (68.0 g = 3 sig figs).
Atomic Mass (H): 1.008 g/mol
Atomic Mass (C): 12.011 g/mol
Atomic Mass (Cl): 35.453 g/mol
Molar Mass (H₂CCl₄): 2(1.008 g/mol) + 12.011 g/mol + 2(35.453 g/mol)
Molar Mass (H₂CCl₂): 84.933 g/mol
68.0 g H₂CCl₂ 1 mole
------------------------- x ------------------ = 0.801 moles H₂CCl₂
84.933 g
