which is completely wrong... the correct answer is: Cr2O72- + 14H+ + 6e- → 2Cr3+ + 7H2O
how would you approach this question, and how can i get that answer?
hopefully this should be my last chem question today.. many thanks
Cr2O7 2- ==> Cr3+ balancing the atoms gives
Cr2O7 2- ==> 2Cr3+ now add waters to the RHS to balance oxygens
Cr2O7 2- ==> 7H2O + 2Cr3+ and add hydrogens to LHS to balance 7H2O
14H+ + Cr2O7 2- ==> 7H2O + 2Cr3+ and then add the electrons, we have a 6+ charge on the RHS and a 12+ charge on the LHS so we need to take six off the LHS so add 6 electrons
Cr2O7 2- ==> 2Cr3+ now add waters to the RHS to balance oxygens
Cr2O7 2- ==> 7H2O + 2Cr3+ and add hydrogens to LHS to balance 7H2O
14H+ + Cr2O7 2- ==> 7H2O + 2Cr3+ and then add the electrons, we have a 6+ charge on the RHS and a 12+ charge on the LHS so we need to take six off the LHS so add 6 electrons
I know this is 8 years late, but it will help me anyways
Its all about balancing.
First you have to balance the Cr Because it is Cr2 on the LHS it will be 2Cr on the RHS this means the charge will be 2- to 6+ As there are 7 oxygen's, the other side must have 7H2O in order to also have 7 oxygens with a neutral charge as 2 H+ balances 1 O-2. Then that means we have 14 H+ which needs to be added onto the other side. Finally balance the electrons. 6+ charge on the RHS 12+ charge on the LHS that means the LHS needs to add 6 electrons which have a negative charge. +6e- to balance the everything out.
I am doing my a-levels now, so plz dont hate that this is a late response.
I know this is 8 years late, but it will help me anyways
Its all about balancing.
First you have to balance the Cr Because it is Cr2 on the LHS it will be 2Cr on the RHS this means the charge will be 2- to 6+ As there are 7 oxygen's, the other side must have 7H2O in order to also have 7 oxygens with a neutral charge as 2 H+ balances 1 O-2. Then that means we have 14 H+ which needs to be added onto the other side. Finally balance the electrons. 6+ charge on the RHS 12+ charge on the LHS that means the LHS needs to add 6 electrons which have a negative charge. +6e- to balance the everything out.
I am doing my a-levels now, so plz dont hate that this is a late response.
Weird to think your probs at uni now and this thread is a decade old.