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Tuesday 28th june gcse ocr chemistry exam c4 c5 c6 higher paper

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Reply 20

Vorsah

Original post by cuckoo99

em the answers to the last question were Al3+ + 3e- = Al
and 2O2- ----> O2 + 4e-

i think :smile:

i didnt get dat

Reply 21

cuckoo99

what did you get then lol ? and im sure what i did is right. but pardon my ignorance if im wrong :smile:

Reply 22

sivaa015.310

Original post by cuckoo99

em the answers to the last question were Al3+ + 3e- = Al
and 2O2- ----> O2 + 4e-

i think :smile:

Im doing this paper for the mock please can u tell me the answer for the last question please: I understand Al3+ + 3e- = Al
but what is 2O2 = O2 + 4e- ????

Reply 23

Cricket1256

I am doing this paper for the Mock as well....

Reply 24

Pride

Original post by sivaa015.310

Im doing this paper for the mock please can u tell me the answer for the last question please: I understand Al3+ + 3e- = Al
but what is 2O2 = O2 + 4e- ????

Original post by Vorsah

i didnt get dat

Original post by cuckoo99

what did you get then lol ? and im sure what i did is right. but pardon my ignorance if im wrong :smile:

2O^2- --> O₂ + 4e^-

Basically, you have 2 O_2- ions on the left. Then two electrons are taken from each oxygen atom, so you have O₂ and 4 electrons...

does that make sense? It's hard to visualise, but it's because it's been balanced, it can be quite confusing.

(edited 12 years ago)

Reply 25

cuckoo99

Original post by sivaa015.310

Im doing this paper for the mock please can u tell me the answer for the last question please: I understand Al3+ + 3e- = Al
but what is 2O2 = O2 + 4e- ????

2O2- -----> O2 + 4e- means : there are 2 oxygen ions with a charge of 2- this means they both have gained 2 electrons but then when u write the arrow( -------->) O2 + 4e- this means the 2 oxygen ions both lost those 2 electrons so now ur left with O2 and the 4 other electrons so
2O2- -----> O2 basicaly means that 2 oxygen ions have lost 2 electrons , this means they are not ions but simple atoms and yuo have the 4 electrons that were bonded to the 2 atoms of oxygen left over
hope that helps