Help with chemistry

Hey im currently going to take a AQA test on chapter 1-7 for chemistry if anyone is confident and good at chemistry can you please help out x

Reply 1

gapyear2018

Original post by heyitscraziix

Hey im currently going to take a AQA test on chapter 1-7 for chemistry if anyone is confident and good at chemistry can you please help out x

I'm quite good at chemistry, what do you need help with?

Reply 2

heyitscraziix

Original post by ScienceFantatic

I'm quite good at chemistry, what do you need help with?

Balancing Equations please

Reply 3

gapyear2018

Original post by heyitscraziix

Balancing Equations please

Ok so here's an example

Na + Cl2= NaCl

So on the left side there is 1 sodium atom(Na) and 2 chlorine atoms(Cl2)

and on the right side there is 1 sodium atom and 1 chlorine atom

We need to balance it to make sure there are the same amount of sodium and chlorine atoms on both sides. So we put a 2 in front of the NaCl(on right)to make 2NaCl. However the 2 multiplies the compound so there are now 2 sodium atoms as well as chlorine atoms on both sides. Since we have an inbalance of sodium atoms we need to add a 2 to Na on the left side to have 2Na

So 2Na+ Cl2= 2NaCl

If we count it up we see there are 2 sodium atoms on both sides and 2 chlorine atoms.

Balance Na+O2=Na2O and tell me what you get

(edited 8 years ago)

Reply 4

Kugelmugel

My trick for balancing equations (hopefully I can explain this!) is to write out what you've started with.

For example, the reaction for photosynthesis:

1) write out the reaction with no balancing numbers, so here:
CO2 + H2O -> C6H12O6 + O2 (imagine the numbers are small!)

2) Write out how much of each atom you have on each side:
Side one (carbon dioxide and water) - C = 1, O = 3, H = 2
Side two (glucose and oxygen) - C = 6, O = 8, H = 12
So now you know how much of each element you have on each side of the equation!

Now you need to play around with these numbers so that they match up, I like to start with an element, for example carbon. As you can see we have 6 times more carbon on one side of the equation than the other, so lets balance that first.

3) So the next step would be to repeat step 2) with the new equation (aka with 6CO2), then work out what else changes from here! AKA because you're now putting 6CO2 the amount of oxygen will also change so you need to balance that too.

I'm sure that sounds really complicated, but once you've done it a few times it becomes fairly straightforward! If you need any clarification don't hesitate to ask!

Is there anything else you need help with? My sister is doing her GCSEs at the moment too :smile:

good luck!

Reply 5

gapyear2018

Original post by Kugelmugel

good luck!

soz m8 beat you 2 it :wink:

(edited 8 years ago)

Reply 6

Kugelmugel

Original post by ScienceFantatic

soz m8 beat you 2 it. For someone who doesn't know how to do it at all- your starter is too complicated js.

Haha I was typing while you posted, yeah you did! I read yours, it explains it way better than mine, I have to admit :colondollar:

Reply 7

gapyear2018

Original post by Kugelmugel

Haha I was typing while you posted, yeah you did! I read yours, it explains it way better than mine, I have to admit :colondollar:

Haha- yours is still helpful- hopefully they understand both examples! Lol

Reply 8

Kugelmugel

Ah one tip I have though, if the question is asking you to write out the equation yourself, make sure you know the formulas of the compounds they use a lot (sodium hydroxide/carbonates/etc) or know how to work them out from the data sheet, I know at A2 sometimes I make mistakes writing the formulas and that makes it a billion times harder to balance!