i'm in yr 12 and i still suck at writting and balancing equations help!

[shady145]

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Originally Posted by squeenie

So that'd make it:



Awesome, nice work.

we can call it a team effort between you, me n anna =)
or if someone wants to correct me, you, anna and I. haha

[Dragonmaster262]

Originally Posted by squeenie

Still trying to balance the equation, but yeah, it's an example of a metal/acid reaction.

Isn't acid + metal-----> salt + hydrogen? If that's true than this equation is impossible.

[annabackwards]

Originally Posted by shady145

we can call it a team effort between you, me n anna =)
or if someone wants to correct me, you, anna and I. haha

Oh, awesome work! I forgot that you couldn't change 2 the Cu(NO3)2... no wonder it didn't work out XD

Originally Posted by Dragonmaster262

Isn't acid + metal-----> salt + hydrogen? If that's true than this equation is impossible.

That is true, but i think your teacher just wanted to know if you could balance something other than the standard reactions.

[autumn-angel]

I think there is an algebraic method to balancing chemical equations, but I don't know if that works in every case...

[Pwnage101]

there is. Using matrices (first year uni maths) helps out, but its is still possible to do without such knowledge.

justlet w, x, y and z, for example, be the molar ratios of each species, eg:

w C2H5OH (l) + x O2 (g) ----> y CO2 (g) + z H2O(l)

and just create a number of simultaneous equations using teh fact that the number of atoms of one element on the left must equal the number on the right, for eg:

2w = y for the C atom

6w = 2z for H atom

w + 2x = 2y + z for O atom

then putting in w for y and z

w + 2x = 2(2w) + 3w

ie w + 2x = 7w

2x = 6w

x = 3w

let w = 1 (will give smalles possible integer set for w, x, y, z)

thus w = 1, x = 3, y = 2, z = 3

thus equation becomes:

C2H5OH (l) + 3O2 (g) ----> 2CO2 (g) + 3H2O(l)

then again i would advise AGAINST using this method in exams, just do it in your head! much, much quicker and easier.

HINT: always do species on LHS and RHS that contain all of one lemenmt on that side

eg in the above example on the LHS ethanol had all Carbons on the left, and carbon dioxide all on the right

thus no matter what values we get, we know that the molar ratio of CO2 MUST BE TWICE the molar ratio of the ETHANOL for it to balance.

same with the H's - we know the molar ratio of H2O MUST BE THREE TIMES that of ethanol.

that gets u:

1 x 2 3

then u can work out how much O is needed, and if u end up witha fraction (eg 7/2) u just doube every term

hope that helps

[Sahand]

i can tell u what ATAR u'll get... if ur in a dumb class (which i think is the case) around 60
does that make u feel good superman??

[shady145]

Originally Posted by Sahand

i can tell u what ATAR u'll get... if ur in a dumb class (which i think is the case) around 60
does that make u feel good superman??

yep ^^ thats all u need, mmmm 60

[shady145]

Originally Posted by Sahand

i can tell u what ATAR u'll get... if ur in a dumb class (which i think is the case) around 60
does that make u feel good superman??

actually i dnt even know y i am at school, i should be saving the world from bad

[1bpcsmem]

Apparently its easier to balance the lower molecular mass specie first. (E.g. Balance hydrogen before oxygen due to oxygen's lower molecular mass) But I don't actually find that particular true as I simply just balance whatever species I feel like balancing first. If you are balancing alkanes, you can use the general formula if you want to although its not recommended:
CnH2n+2 + [(3n+2)/2]O2 ---> (n+1)H2O + nCO2

[adomad]

hey world, i just had a chem exam and this was one of the formulas that i had to balance. i got it after like 10 mins!!!! so stressful.



have fun

[shady145]

lol 10 minutes??? wat for, it just wasn't coming to u.
it took around 1 minute for getting my numbers right then another minute to check the atoms on each side
1:4------->1:2:2

[adomad]

Originally Posted by shady145

lol 10 minutes??? wat for, it just wasn't coming to u.
it took around 1 minute for getting my numbers right then another minute to check the atoms on each side
1:4------->1:2:2

i was exaggerating. probs like 3 or 4 and seeing how i normally do them faster, i was worried that i wouldn't finish the test on time

[greenie1113]

well you do em heaps quicker than i do

but thanks loads for all yoor help!!!

im slowly gettin better
hehe
but i'll get there soon enough =]

[evilelmo_2005]

Originally Posted by shady145

my teacher isnt the best either, she plays WOW instead of preparing our lesson XD
write and balance this. ethane burning in an excess of oxygen

MY PHYSICS TEACHER PLAY WOW TOO! wat's with teachers and WOW these days

[shady145]

Originally Posted by adomad

i was exaggerating. probs like 3 or 4 and seeing how i normally do them faster, i was worried that i wouldn't finish the test on time

ooo lol yea i c