Redox equations

[minilunchbox]

I'm having trouble balancing

and


I keep getting the wrong answer. Eep.

[chem-nerd]

Cu(s) -> Cu²⁺(aq) + 2e

HNO₃(aq) + 3H⁺(aq) + 3e -> NO(g) + 2H₂O(l)

3Cu(s) + 2HNO₃(aq) + 6H⁺(aq) -> 3Cu²⁺(aq) + 2NO(g) + 4H₂O(l)


PbS(s) + 4H₂O(l) -> PbSO₄(s) + 8H⁺(aq) + 8e

H₂O₂(l) + 2H⁺(aq) + 4e -> 2H₂O(l)

PbS(s) + 4H₂O(l) + 2H₂O₂(l) + 4H⁺(aq) -> PbSO₄(s) + 8H⁺(aq) + 4H₂O(l)

cancel out H⁺ and H₂O

PbS(s) + 2H₂O₂(l) -> PbSO₄(s) + 4H⁺(aq)

[minilunchbox]

The answers in the book says it's


and

[chem-nerd]

the first one is the same (they've just ionised the nitric acid)

and woops by me on the second one for having H⁺(aq) with no water present

[nala]

Just a couple of tips my chem teacher taught me when balancing redox equations (they make it much easier!):
-> firstly, balance the ions or metals involved (eg. Cu, Fe etc)
-> balance oxygen by adding the necessary number of water molecules to the needed side of the equation
-> balance hydrogen by adding H+
-> balance charges by adding electrons

this really helped me when I was struggling with redox, hope it helps!

[minilunchbox]

Just a couple of tips my chem teacher taught me when balancing redox equations (they make it much easier!):
-> firstly, balance the ions or metals involved (eg. Cu, Fe etc)
-> balance oxygen by adding the necessary number of water molecules to the needed side of the equation
-> balance hydrogen by adding H+
-> balance charges by adding electrons

this really helped me when I was struggling with redox, hope it helps!

KOHES method, yeah?

[nala]

I'm pretty sure that's it, it sounds familiar. I could just never remember what the letters stood for (I can never remember things like that ), so I just remembered the dot points.

[vcesuccess]

Just a couple of tips my chem teacher taught me when balancing redox equations (they make it much easier!):
-> firstly, balance the ions or metals involved (eg. Cu, Fe etc)
-> balance oxygen by adding the necessary number of water molecules to the needed side of the equation
-> balance hydrogen by adding H+
-> balance charges by adding electrons

this really helped me when I was struggling with redox, hope it helps!

Thats correct. Follow that and you'll never be wrong. Perhap you could copy that in your notebook.