Urgent help with chemistry please...

This has got to do with redox equations. I have to determine what is oxidized and what is being reduced, and what the oxidizing and reducing agents are. The equation is as follows:
2Cs + Br2 ---> 2CsBr
I wrote down that caesium is being reduced therefore it's the oxidizing agent, and bromine is being oxidized thus it's the reducing agent. After checking the answer sheet I realised it's the other way round but I don't understand why. Caesium has a 1+ charge so if it's becoming neutrally charged, it's gaining an electron... Hence why I put reduction. Can someone please explain this to me/ I would very much appreciate it. Thank you in advance.

Reply 1

Formless

17

All Uncharged (uncombined and free) species (Cs) have an oxidation number of 0 to begin with.
CsBr, (Cs has an oxidation of +1) and (Br has -1) thus OIL RIG - Caesium loss an electron and gave it to Br so it (Cs) is Oxidised

(edited 8 years ago)

Need state symbols.

Original post by futbol

Need state symbols.

+1 rep

Reply 4

danr2

3

actually the book is right.. if you expand the equation and right the ionic equation for both you'll get 2CS---2Cs+ + 2e- and br2--2br + 2e-

you could see from there that caesium is being oxidised and barium is being reduced

Reply 5

a.j.lovett

1

Hello, I am a second year chemistry undergrad. The pneumonic you need to remember is OILRIG; Oxidation is losing, Reduction is gaining. You then need to identify what is gaining/losing an electron. Caesium starts off neutral, then forms
Cs + in the salt, CsBr. Caesium has lost an electron and therefore is oxidised. Bromine has gone from being neutral to being negatively charged, it has gained an electron and so is reduced.

An oxidising agent oxidises what it is being reacted with and so the oxidising agent is reduced. I think you understand that concept, you have just got your answer muddled! I hope this helps!

Reply 6

Wolfram Alpha

OP

20

Original post by Formless

All Uncharged (uncombined and free) species (Cs) have an oxidation number of 0 to begin with.
CsBr, (Cs has an oxidation of +1) and (Br has -1) thus OIL RIG - Caesium loss an electron and gave it to Br so it (Cs) is Oxidised

Thank yo for your help.

Reply 7

Wolfram Alpha

OP

20

Original post by a.j.lovett

Hello, I am a second year chemistry undergrad. The pneumonic you need to remember is OILRIG; Oxidation is losing, Reduction is gaining. You then need to identify what is gaining/losing an electron. Caesium starts off neutral, then forms
Cs + in the salt, CsBr. Caesium has lost an electron and therefore is oxidised. Bromine has gone from being neutral to being negatively charged, it has gained an electron and so is reduced.

An oxidising agent oxidises what it is being reacted with and so the oxidising agent is reduced. I think you understand that concept, you have just got your answer muddled! I hope this helps!

Thanks for your help; it was of great use to me. Have a good day.

Reply 8

Wolfram Alpha

OP

20

Original post by danr2

actually the book is right.. if you expand the equation and right the ionic equation for both you'll get 2CS---2Cs+ + 2e- and br2--2br + 2e-

you could see from there that caesium is being oxidised and barium is being reduced