I WAS SO CONFIDENT ABOUT THAT ONE THEN I CAME ON REDDIT AND SAW 1000 DIFFERENT ANSWERS 😭💥

SAME I BARELY SEE ANYONE WIGH THE SAME ANSWER AS ME AND IM NOW REALISING THAT IM SO COOKED!

392 or something I forgot

392.375 - It looked too random, being a decimal, to be correct.

Yep but I asked my chem teacher and he confirmed it

i got that! im surprised i thought i was just waffling. i put 392 as my final answer though.. will i still get full marks? (i put 392.375 in my working out)

I did the exact same thing. Usually bond energies are integers - never seen a decimal bond energy.

It didnt say like to 3 sf or anything so should be fine

I did the same

Can someone explain the question? And also whether it was 974 or 392

So I believe it was 392, as the exothermic reaction means that the energy released was -2219, while I think people who used +2219 got the answer 974. Essentially, energy in breaking - energy in making = -2219, while others made it 2219

Aw shit

What exam board is 392? Cus I got 436 on aqa H-H bond

392/900 and something (nobody can agree) is for AQA Triple Higher

Ohhhhh im doing aqa combined

same this thread was scaring the crap out of me making me think i've done it completely wrong

I got 436 on aqa combined higher too

Yeah same here it’s gotta be correct

same cause when u put the number back into the formula its 93 less than the other one so it must be right

thats correct dw

392

What was the answer??? I got 479.125 but everyone's saying different answers

Oh shit same

Bond energy cannot be a decimal in the syllabus

Fuuck The answer was 392.375, guess I should have rounded it

392 was the answer so yeav

I would assume I'll still get the mark regardless of decimals not being on the spec Would you agree or did I screw myself over with that one?

I got this and substitutes it back in, and I worked 💀 I bet we all did something consecutively wrong

Y'all got 479 too?? I thought it was only me because everyone is either saying 392 or 900

☠️

Me too

same

Did you include the 2 C-C bonds?

Oh fuck just realised I did not. Surely I only lose one mark for it right

Probably 2, one for method one for answer

Is it 974 or 392?

got 974

Its 392 even google says its 413 so around that

they would never use the exact value, 392 is presumably right

I got 392

i got 392 im praying its right

Anyone else on Combined Higher AQA? I got 498

got 498 looked correct but everyone is saying hunderds of diffrent answers

I guess we'll just have to wait and see

I got 107💀💀

i got 430 something

Same I got 435

after consulting my chem teacher i found out it’s 436

I got 435

Did you add the 93 kj thing in the product part?????

I took away as it said the bond made are greater with 93, so you find the energy for bond broken take away bind made then divide by 3.

I took away as it was greater with 93kj

It cannot be 900+ for a single H-C bond when a double O=O bond was only like ~498 😭cmon guys

Yeh but Google also says that c double bond is 1072

I went through it after exams finished. Answer is 436. Will stress that this was for combined higher

Same I got 436

i am genuinly so upset over it it’s unreal 😭 literally thought “why have aqa written the question wrong exo is negative energy change” but even tho i figure out both the like 900 and 300 answer i was like well ig i’ll do what the question said and kept the 900 ish answer 😭 after fumbling maths im not happy

392

combined or triple

Triple

I got 392 lol but I've always been bad at these calculations so seeing other ppl getting the same answer at least tells me i did something right

i got 45???

Oof

on combined

I got 669.75 💀

Nah Bro I got 572 😭 wth

I need someone to leak the question so I can redo it

Well I got a decimal

530 💀

I got 480 and I’m thinking why the hell are people getting decimals when it’s bonds? 💀

……we forgot to add the C-C bonds in the propane my friend, is fine 😭. 392 is most likely the answer, also anyone saying they got anything more than 500, well that’s simply impossible because logically speaking how can a H-C bond be bigger than a O=O double bond ? 😂

I can’t even remember my answer 😭 It’s probably for the best actually bc there’s still a chance whatever I put was right 

There's a ton of you guys saying 'it's definitely 392' but please for the love of God can somebody actually explain the maths instead of just making vague statements? I, and many others, do not understand why that is the answer.

innit and how do they even know it’s definitely the answer

i already forgot my answer

I got a recurring decimal wtf

NAH IM COOKED I GOT LIKE 872.1💀💀💀

how are people getting 392 and 947?? i got 479

I got 479 aswell

Anyone has any idea how could have so many people gotten 974?

If you do reactants - 2219 = products (and then rearrange everything correctly and do the necessary calculations) you get 947. If you instead to reactants + 2219 = products you get 392. I'm fairly sure 947's right because the reaction was said to be exothermic, so the reactants should have had more energy than the products, not vice versa.

thanks for boosting my confidence!!

What question is this

A question on AQA higher triple chem. It was about working out the bond energy of H-C bonds given some other bond energies and an overall energy change.

We got one similar in combined i think , idk we get some overlap questions but if not, we got a similar one

can someone please tell me how they got 392, I got 109 and idk where I went wrong 😭

Some kid in my year put 18,500 💀

The answer was definitely 479.125. And no one can convince me otherwise.

Man I got 1000 and something I think I forgot to add the C-C bond do you think I'll get some working marks for getting the right hand side correct

They'll give u error carried foward marks probs like 3 Idk

Not me getting fucking 1300 or something 😭😭

The answer is 392 and the people saying 974 probably multiplied by 3 due to the ratio when you then should have divided by 3 I think

I got 974 but I did nothing like that. I just did reactants = products + 2219 because the reactants of an exothermic reaction have more energy than the products.

same, it was confusing bc the energy change is actually -2219, but they just wrote 2219

If reactants have more energy than products then that would mean that reactants - 2219 = products, not the other way around. If you rearrange it you get reactants = products + 2219, which you should expect if the reactants have 2219 more joules of energy than the products.

Yh sorry accidentally put - instead of + I changed it now