Question

How many moles are there in 20.0 grams of FeCl₃?

a) 0.123 moles.
b) 0.164 moles.
c) 0.273 moles.
d) 0.345 moles.

Answer 1

The number of moles in 20.0 grams of FeCl₃ is calculated by dividing the mass of the substance by its molar mass, resulting in 0.123 moles.

Step-by-step explanation:

To calculate the number of moles of FeCl₃ in 20.0 grams, first we need the molar mass of FeCl₃. The molar mass of FeCl₃ can be calculated as (55.85 amu for Fe) + (3 x 35.45 amu for Cl) = 162.2 amu. Next, we use the formula: moles = mass (g) ÷ molar mass (g/mol), which gives us moles = 20.0 g ÷ 162.2 g/mol. Calculating this, we find 20.0 g ÷ 162.2 g/mol = 0.123 moles. Therefore, the correct answer is a) 0.123 moles.