Answer:
Molarity Cu²⁺ = 0.423M Cu²⁺
Step-by-step explanation:
40.8g of copper (II) acetate into 200mL of a 0.700M sodium chromate
The reaction of copper acetate with sodium chromate occurs as follows:
Cu(CH₃COO)₂(aq) + Na₂CrO₄(aq) → CuCrO₄(s) + 2CH₃COONa
In water, the Copper(II) acetate dissociates in Cu²⁺ cation.
To know final molarity of Cu²⁺ we need to calculate the moles of Cu²⁺ that don't react with chromate ion, thus:
Moles of 40.8g of copper(II) acetate (Molar mass: 181.63g/mol) are:
40.8g × (1mol / 181.63g) = 0.2246 moles of Copper(II) acetate
Moles of sodium chromate are:
0.200L ₓ (0.700mol / L) = 0.140 moles of sodium chromate.
As 1 mole of Copper(II) acetate reacts per mole of sodium chromate, moles of Copper(II) acetate = Moles of Cu²⁺ that remains after the reaction are:
0.2246mol - 0.140moles = 0.0846 moles of Cu²⁺
Molarity is ratio between moles of solute (Moles Cu²⁺) and volume in liters of solution (200mL = 0.200L):
Molarity Cu²⁺ = 0.0846 moles / 0.200L
Molarity Cu²⁺ = 0.423M Cu²⁺