Answer to Question #246427 in Chemistry for Yaya.13

Question

A beaker contains 7.85 g of Cu2O. A second beaker contains some FeCl3. If the two beakers contain the same numbers of formula units, what is the mass of the FeCl3?

Answer 1

Solution:

Mass of Cu₂O is 7.85 g

The molar mass of Cu₂O is 143.09 g/mol

Therefore,

(7.85 g Cu₂O) × (1 mol Cu₂O / 143.09 g Cu₂O) = 0.05486 mol Cu₂O

n(Cu₂O) = 0.05486 mol

Since the two beakers contain the same numbers of formula units, then:

N(Cu₂O) = N(FeCl₃)

n(Cu₂O) × N_a = n(FeCl₃) × N_a

where N_a is Avogadro's number (6.022×10²³ formula units mol^-1)

Therefore,

n(Cu₂O) = n(FeCl₃)

n(FeCl₃) = n(Cu₂O) = 0.05486 mol

The molar mass of FeCl₃ is 162.2 g/mol

Therefore,

(0.05486 mol FeCl₃) × (162.2 g FeCl₃ / 1 mol FeCl₃) = 8.8983 g FeCl₃ = 8.90 g FeCl₃

Mass of FeCl₃ is 8.90 g

Answer: The mass of FeCl₃ is 8.90 grams.