Question

In a certain electrolysis experiment, 1.24 g of Ag were deposited in one cell (containing an aqueous AgNO3 solution), while 0.650 g of an unknown metal X was deposited in another cell (containing an aqueous XCl3 solution) in series with the AgNO3 cell. Calculate the molar mass of X.

Answer 1

Answer:

The correct answer is 169.56 g/mol.

Explanation:

Based on the given information, the mass of Ag deposited is 1.24 g, and the mass of unknown metal X deposited in another cell is 0.650 g. The number of moles of electrons can be determined as,

= 1.24 g Ag * 1mol Ag/107.87 g/mol Ag * 1 mol electron/1 mol Ag ( the molecular mass of Ag is 107.87 g/mol)

= 0.0115 mole of electron

The half cell reaction for the metal X is,  

X^3+ (aq) + 3e- = X (s)

From the reaction, it came out that 3 faraday will reduce one mole of X^3+.  

The molar mass of X will be,  

= 0.650 g/0.0115 *3 mol electron/1 mol

= 56.52 * 3

= 169.56 g/mol