Identity of metal from electrolysis

AI Thread Summary
The discussion focuses on identifying a trivalent metal ion based on electrolysis data, where 1.18g of metal was plated out using a current of 5.0A for 10 minutes. The calculations reveal that 3000 coulombs were used, leading to 0.031092 moles of electrons and subsequently 0.010364 moles of the metal. Through trial and error, the molar mass of indium was found to be the closest match at 114.82 g/mol, compared to the calculated molar mass of 113.86 g/mol. The conclusion confirms that indium is the correct identity of the metal. The discussion emphasizes the importance of using the molar mass formula for accurate identification.
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Homework Statement


A solution of a trivalent metal ion is electrolysed by a current of 5.0A for 10 minutes during which time 1.18g of metal was plated out. The identity of the metal is:

A cobalt
B chromium
C indium
D gallium
E bismuth

Relative atomic masses:
1 faraday = 96,486 coulombs.

Homework Equations


current*time=coulombs
coulombs/96486=faraday
1 faraday = 1 mol of electrons

The Attempt at a Solution


5.0*10*60=3000 coulombs
3000/96486=0.031092 mol of electron

Since trivalent metal ion, mol of metal = 0.031092/3 = 0.010364 mols

Trial and error by dividing 1.18 by molar mass shows indium is closest. 1.18/114.82 = 0.1028. Is this the correct answer?

Cheers!
 
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Yes, indium sounds good.
 
Thanks!
 
To avoid trial and error use this formula:

Molar mass (g/mol)=mass(g)/number of moles(mol)
M=m/n
M= 1.18g/ 0.010364 mol
M=113.86 g/mol

Cd
113.86-112.41=1.45 difference
Indium
114.82-113.86=0.96 difference

So the closest answer is Indium
 

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