Redox chemistry: help me understand the answer
I don’t get how the mark scheme gets a 3:2 mole ratio. Can someone explain?
Cr electrode increases in mass therefore Cr3+ is being reduced to Cr. Cr3+ + 3e- -> Cr
X electrode decreases in mass so X is being oxidised. X is 2+ as it makes XSO4 and SO4 has charge 2-. Therefore X -> 2e- + X2+
To combine the equations you need to multiply the Cr one by 2 and X one by 3. Total equation would be 3X... -> 2Cr...
Therefore Cr:X is 2:3.
I assume the top line 'question is about d-block metals' refers to the rest of the question which is why they used Mg which isnt a d-block metal.
X electrode decreases in mass so X is being oxidised. X is 2+ as it makes XSO4 and SO4 has charge 2-. Therefore X -> 2e- + X2+
To combine the equations you need to multiply the Cr one by 2 and X one by 3. Total equation would be 3X... -> 2Cr...
Therefore Cr:X is 2:3.
I assume the top line 'question is about d-block metals' refers to the rest of the question which is why they used Mg which isnt a d-block metal.
(edited 10 months ago)
Original post by user8937264980
Cr electrode increases in mass therefore Cr3+ is being reduced to Cr. Cr3+ + 3e- -> Cr
X electrode decreases in mass so X is being oxidised. X is 2+ as it makes XSO4 and SO4 has charge 2-. Therefore X -> 2e- + X2+
To combine the equations you need to multiply the Cr one by 2 and X one by 3. Total equation would be 3X... -> 2Cr...
Therefore Cr:X is 2:3.
I assume the top line 'question is about d-block metals' refers to the rest of the question which is why they used Mg which isnt a d-block metal.
X electrode decreases in mass so X is being oxidised. X is 2+ as it makes XSO4 and SO4 has charge 2-. Therefore X -> 2e- + X2+
To combine the equations you need to multiply the Cr one by 2 and X one by 3. Total equation would be 3X... -> 2Cr...
Therefore Cr:X is 2:3.
I assume the top line 'question is about d-block metals' refers to the rest of the question which is why they used Mg which isnt a d-block metal.
Thanks, this makes a lot of sense
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