An unknown metal chloride with the formula MCl3 undergoes electrolysis using a current of 6.50A for 1000 s and desposits 1.56g. What is the molar mass of the metal?
To find the molar mass of the metal, we need to know the amount of moles of the metal deposited during electrolysis.
Given:
Current = 6.50A
Time = 1000s
Mass of metal deposited = 1.56g
First, let's calculate the charge passed through the electrolyte using Faraday's law of electrolysis.
Q = It
Q = 6.50A * 1000s
Q = 6500 C (Coulombs)
Next, let's calculate the moles of electrons passed using Faraday's law of electrolysis.
1F (Faraday) = 96485 C
Moles of electrons passed = Q / 1F
Moles of electrons passed = 6500 C / 96485 C/mol
Moles of electrons passed = 0.0674 mol
Since each metal ion is reduced through the gain of three electrons (M3+ + 3e- -> M), the moles of metal deposited is one-third of the moles of electrons passed.
Moles of metal = 0.0674 mol / 3
Moles of metal = 0.0225 mol
Finally, we can calculate the molar mass of the metal using the formula:
Molar mass (g/mol) = Mass of metal deposited (g) / Moles of metal
Molar mass = 1.56g / 0.0225 mol
Molar mass ≈ 69.3 g/mol
Therefore, the molar mass of the metal is approximately 69.3 g/mol.