GCSE Chemistry - Bond Energies #44 (Higher tier)

This video covers:
- What bond energies are
- That bond breaking is endothermic
- That bond formation is exothermic
- How to calculate bond energies
- Two example calculations
This video is suitable for:
- Higher tier only
- All exam boards
- Triple and combined science

[@Cognitoedu]

Hello everyone - please be aware that for the last example, the energy for the reactants actually totals 2249, and not 2330 as we say in the video. Sorry for any confusion that caused!

[@akessi4755]

i was gonna say XD its fine

[@thekingofweebs9825]

Npp

[@roronoazoro250]

@@patrickstar1394 the guy in the freesciencelessons channel explains it really well if youre still confused

[@doubledd4831]

@@roronoazoro250 yeh, I just checked it out , thank you so much Roronoa

[@rizbroz742]

It's ok cognito

[@fatemafarahat4119]

I've been having alot of trouble understanding this topic and calculating overall energy change at school. I just watched this video and I understand everything so well now! Thank you so much! All your videos are awesome and help me aloooot with my studies.

[@Cognitoedu]

Great to hear, thank you!

[@zaynabzaman285]

thank you, love that these videos can be used at any time like 2 hours before the exam :D

[@issjjd4651]

💀 its almost 5am and I have an exam in 3 hours

[@ASerbUser]

@@issjjd4651 hope u did good girlie, i have an exam tomorrow and its 11PM rn i dont know muchh💀

[@issjjd4651]

@@ASerbUser 😭tyy good luck i have another biology today

[@heynotizzy7493]

Ya dead

[@willnorton8236]

melon

[@jackbashford5810]

I did my own working for the last example, and I didn’t get 2330 for the reactants. I actually got 2249, could you help me?

[@Cognitoedu]

Hi Jack, thanks for pointing this out - you’re totally correct. We’ll need to redo this soon - cheers for letting us know :)

[@loujane9181]

same!!

[@lizziebiology]

Me too. I think the dude just made a mistake that's all :)

[@KatieSmith934-56]

ye same i was really confused

[@mr.random8370]

@@Cognitoedu same!!!!!!!!!

[@ashtonclark6063]

Who is here in quarantine

[@nabeelahmed4862]

@Nazmul Huda hahah funny joke let's all laugh hahahhahuauhahuhuauaha

[@erin-iq8tm]

im going to fail chemistry omg edit i got a 9 🤑🤑🤑

[@eesaatava1665]

not if you're subscribed to this guy

[@hamzaabbasi2855]

Out a hundred isn't an achievement

[@erin-iq8tm]

@@hamzaabbasi2855 9 is equal to an a** its literally the highest grade you can get ??

[@hamzaabbasi2855]

@@erin-iq8tm I never said you did bad. I was stating a fact independent of your comment

[@erin-iq8tm]

@@hamzaabbasi2855 well that just doesn't rly make sense

[@thoughtsbright7928]

I hope you get over 1 million subscribers, you deserve it, I think compund intrest is taking place. THANK YOU. it really helped me wayyy better than my teacher explaintion.

[@areebamasood1819]

i am watching your each and every video with my full attention , i am having my igcse a day after tomorrow and it is really helping me. Thanks a lot

[@LukeFisher-k8r]

Hey just wanted to say the question on your website I think is wrong. Total bond energy of products: This is what is displayed as the total reaction energy or the energy required to break the bonds of the reactants (on your website). (3 x 413) + (1 x 339) + (1 x 427) = 2005 kJ This is what it should be unless I have made a silly mistake. (1293)+(339)+(427)=2059 kJ It just means when you subtract your answers the answer is obviously wrong. Just wanted to say thank you so much for your videos though they have helped me so much along with your website.

[@mohamedhisham5249]

Is this calculation (overall energy change) same as "Enthalpy change" ? thanks for your efforts.

[@nehamendes9621]

Wow this is actually really helpful

[@belinadehey1383]

For the last example i have got -97 as an answer not -16. could you help plox?

[@sanamgillani8465]

i got that too

[@fatimamohamed7893]

he made a mistake

[@sourrice1741]

Yep you are correct, they’re wrong and he said this in another comment

[@LiseniMqala]

Cognito you are actually my teacher thank you man❤❤

[@giftndagire1169]

Sorry was hitting the like button don’t mind the feedback…you just saved my national exams bro❤️

[@nelzhang161]

You are my life saviour!!! I love you so much

[@zaynazaman195]

i was wondering how you got +431 kj/mol at 00:34 ? Other than how to get the energy required, i understand this topic really well thanks to these videos

[@keeranaravinthan]

how are we supposed to know the diagrams of the molecules. like in the last one 2NH3, how are we supposed to know that N binds to 3 H molecules

[@unclekabab9849]

Hey Cognito, Do you ever have to balance an equation first before drawing out the bonds or do they give an already balanced equation in the exam?

[@LincolnJames-k4c]

I was having trouble understanding this topic at school. Tho know I understand this so well after watching this. Ty

[@YashbaLalani]

Is it just me or most of the underrated teachers are the best btw why did u draw 3 lines in N and N cuz the reaction is only between 2 Ns

[@NeoUno866]

I don't get the same answer for the energy required to break bonds. I get 2249 kJ/mol. Have I missed something?

[@ronelsahabandu4208]

recheck your calculations. u must have missed a value or sign

[@NeoUno866]

@@ronelsahabandu4208 Energy required to break bonds is wrong, check it yourself: (1 x 941) + (3 x 436) = 2249 (written as 2330 in the video)

[@NeoUno866]

@@ronelsahabandu4208 Just read a comment below, didn't see it before, they're planning on redoing the video I think.

[@leona34]

@@NeoUno866 you got it correct he made a mistake that’s all

[@Noor-yz3uf]

@@NeoUno866 why is only 3 times shouldn’t it be 6 cuz 2x3 is 6

[@azeenzahid]

you are so good at you r thing, thank you soo much, i am saved in my tests

[@fatimaabdulaal791]

thank you so much you helped me understand the topic so well

[@sumanpaul9512]

i need help to know where the six comes from in the last sum?

[@weronikao4430]

Bit late but if you mean the 6 N-H bonds its because there are 2 lots of NH3 bonds (NH3 means N-H, N-H, N-H) so there are 6 bonds altogether (2 x the 3 N-H bonds) Then you do 6 x 391kJ/mol (the energy required to form N-H bonds) to get 2346 kJ/mol for the total energy needed for the reactants

[@AbdulMajeed-eb9zp]

Thanks bro you just saved my test 😅

[@GarbageBandit]

Thank you so much for helping me understand this :)

[@willbonser9695]

really helpful. thank you!

[@epicrodri5355]

You teach brilliantly

[@yashamumtahina]

Thank you so much this video helped me a lot to understand. However, I wanted to know why we didn't multiply 2 with the bond energy for 2NH₃.

[@ashleyminder]

The bond energy for 2NH₃ is multiplied by 6 instead of individually by 2 and 3. Hope this helps :D

[@sadhanasingh1189]

So nice.really helpful

[@ObaidAlbalushi-l3r]

I really love your videos sir! keep up the good work! but can you please a video about co_ordinate bonds?

[@JohnDoe-rr6ou]

When will all your videos finally be uploaded?

[@Cognitoedu]

Hi Wais, cheers for the comment. We're currently working through the chemistry material for double award chemistry, and then physics. We're not exactly sure when they'll all be complete; but we're going as fast we can! The chemistry series will be complete in plenty of time for the exams this year. We're not sure how far through the physics material we'll get through yet :)

[@JohnDoe-rr6ou]

Cognito okay thank you :)

[@Noor-yz3uf]

Um why 3H2 only written 3 times shouldn’t it be 6

[@killeralexio]

Thank you for the help.

[@labik6273]

how do you understand that the nitrogen is in a triple bond form not double bond, i just dont get it

[@tntyeeter7532]

Bond Energies: Bond energy is the amount of energy needed to break one mole of a specific covalent bond. It is measured in kilojoules per mole. Endothermic and Exothermic Processes: Breaking bonds is an endothermic process, requiring energy from the surroundings. Bond formation is exothermic, releasing energy to the surroundings. Reaction Example (Hydrogen + Chlorine → Hydrogen Chloride): Breaking hydrogen-hydrogen and chlorine-chlorine bonds requires energy (endothermic). Forming two hydrogen-chlorine bonds releases energy (exothermic). Overall reaction energy change is calculated as the energy required to break bonds minus the energy released by forming bonds. Calculation Example: For the example reaction, the calculation involves the energy required to break the hydrogen-hydrogen and chlorine-chlorine bonds, minus the energy released by forming two hydrogen-chlorine bonds. Result: -184 kilojoules per mole, indicating an exothermic reaction. Another Example (Nitrogen + Hydrogen): Breaking one nitrogen-nitrogen triple bond and three hydrogen-hydrogen bonds (endothermic). Forming six nitrogen-hydrogen bonds (exothermic). Overall calculation results in -16 kilojoules per mole, indicating an exothermic reaction.

[@mhmm_em]

Cognito I love you!

[@tahaaaa-91]

Nice job dude

[@reisamiah462]

do you need to know how to label bond breaking and making on energy level diagrams

[@Cognitoedu]

Hey - yep you do need to know to write the energy change on the line, and to know which type of change (positive or negative) means bond breaking or bond making. I hope this answers your question! If not please ask again :))

[@reisamiah462]

@@Cognitoedu what do you mean by on the line"

[@Cognitoedu]

On energy change diagrams you have a horizontal line where you write the energy of the product/reactant, and that your arrow launches from and to. You need to label the energy values on those lines but don’t usually need to label ‘bond breaking’ or ‘bond forming’ on those diagrams :)

[@reisamiah462]

@@Cognitoedu oooooh ok ty

[@fatimamohamed7893]

@@Cognitoedu how do you know if its right or left?

[@kpopfanboy-vd4en]

Thx for help !

[@siphomamba-dv2ri]

How did you get the 2346

[@nirishvelraj6470]

can u explain how there is a triple bond in nitrogen at 3:26

[@zainyamin9973]

3 pairs of electrons are shared

[@zen8877]

@@zainyamin9973 how did he know to write that tho?

[@Eren_yaeger-v1m]

Why is Nitrogen not a single bond instead of a multiple bond

[@inkz3520]

as nitrogen is in group 5 it has 5 electrons in its outer shell so it needs to covalently bond with another nitrogen and both of them will share 3 of their own electrons so they both have a full shell with 8 electrons. In the questions they give you what bond it is anyway so don't worry about it too much

[@Eren_yaeger-v1m]

@@inkz3520 thank u so very much

[@Eren_yaeger-v1m]

@@inkz3520 fr needed that

[@tayl7rr241]

ONLY DOIN THIS THXS 2 COVID

[@yixyaxo]

ily

[@ryumadong7435]

gg ez

[@peterbowyer9923]

shoutout to Mathew simon he's got a shit trimmmm

[@echojr9886]

Thought you were meant to be a science channel cant do maths

[@francoistosi6883]

:(

[@khawlasamir8590]

Correct Answer for the last example: 2249-2346= -97 KJ/mol exothermic reaction because of the (-) sign. Thank you Cognito for your clear and straightforward explanation 😊 Keep it up!

[@lillylucie6066]

corona work!!!!!!!!!!!!!!

[@the81kid]

Just an FYI for anyone watching panicking that they don't get the same answer to the final problem: the answer is actually -97 kJ/mol (still exothermic) Don't want to complain about the video or videos though. I just wanted to help anyone watching. These videos are very clear and helpful. Many thanks!

[@drmaximole5956]

thanks bruh i was fr dumbfounded

[@itzpyxal]

Blud no need to complain he pinned the comment..

[@mrbosshindhi]

thanks bro I was also confused

[@user-gi3yr1gl7j]

You are so underrated thank you for your work

[@octannex]

You are the best teacher!

[@imranmughal4003]

You honestly need more views! The way you teach is wonderful! I told ALL my friends about your channel!!!

[@Cognitoedu]

Ah thank you very much Imran, we really appreciate it 😊

[@georgefelix6311]

Love the videos, the best educational KZbin channel out there

[@tedparsons2763]

Train

[@Rimple1985]

Thanks You So Much, I had Problems With It When I Was Taught In School But You Solved All My Problems.❤

[@DanielParton-jf7bb]

Really helped thanks!

[@zen8877]

How did you know that Nitrogen had a triple nitrogen nitrogen bond?

[@ParthPatel-oo4ku]

as nitrogen is in group 5 it has 5 electrons in its outer shell so it need to covalently bond with another nitrogen and both of them will share 3 of their own electrons so they both have a full shell with 8 electrons

[@zen8877]

@@ParthPatel-oo4ku thank you !

[@ahmedelamin1499]

hello i enjoy your videos but i have a question: When hydrogen bonds break, how are you certain that they will react with chlorine instead of hydrogen again?

[@sadewwidhanalage1900]

Thank you soo much for such clear explanations!

[@CL-fn7xj]

-97

[@burcu3444]

what a great lesson, thank youu

[@furkankuasar]

How come it can be exothermic if the products' bond energy is higher than the reactants? Can not understand.

[@Alexander-t6y]

The answer is -97 for the last example.... they made a mistake when they got 2330

[@erasalliu315]

The last example you shared with us is wrong because 941+3(436)= 2254 and not with 2330 as you wrote and the energy change is -92 kJ/mole

[@helpdesk482]

It is actually 2249

[@helpdesk482]

Energy change is -97

[@colemantong8359]

Hello there. Thank you so much for your helpful videos. I am a high school teacher and I would like ask if I could take screenshots of your video to use them for teaching purposes in my classroom?

[@Cognitoedu]

Hi Coleman, yep that's fine 👍 Thankyou for asking!

[@boombox2847]

Hi What App Did You Use To Make This?

[@danielstacey2660]

These are really fantastic videos. Thankyou

[@Cognitoedu]

Thanks very much Daniel!

[@l.p.m6716]

Thank u so much cognito this helped alot

[@xD-Hi]

can someone explain wtf is a double bond or a triple bond?!?

[@articticcblu]

amount of electrons they share between each other

[@Lunaassss]

One Question please answer as the exam is tmr and i have this confusion in 2:30 why do we um i dont know multiply by 2 with 431?? Please tell because my exam is tmr!! March 3rd 😭

[@articticcblu]

2 because there are 2 H-Cl bonds

[@deepajayan3328]

Thank you

[@pranaysanghvi1697]

Thank you

[@maryamalwahaibi4941]

Omg thank you so much I have a final exam soon and your video helped so much❤.

[@xyeonjvnzx]

3:54 why do u times by six

[@articticcblu]

because there are 6 N-H bonds, you can see

[@jellyparramore6458]

who ells is here because of your teacher?

[@danielkyereh1995]

what softwares did you use to make these videos

[@UniqueAkbar]

Y does nitrogen have triple bond even tho the base was 2

[@AbdulMajeed-eb9zp]

Bro the ans of the last one is -97. Pls help !!!

[@EPICGamer-ee2qm]

Uhh! What else can I say than just Thank You! :)

[@SalsaKingoftheApes]

Really clear, thankyou

[@nginaannie5015]

thank you in advance.😌

[@Anne-uh5rj]

a small doubt, if my answer is a positive value then is it an endothermic reaction ?

[@saadkamran5740]

Yup positive value means endothermic.

[@katieyakip5497]

Omg ty so much bro😊👍

[@Brochesski]

I’m in year 8 and about to have my end of year tests, and this really helped me, Thank you! Edit: Now i also understand higher level questions and can say that i fully understand this!

[@Cognitoedu]

Great work Noah, glad we could help 😊

[@Brochesski]

@Rockdude Clamer well i picked them this year cos im in year 9 so ig theyre close now 🤷‍♂️

[@eveyxp]

@@Brochesski yeah year 10 sucks , can't believe you were doing this in year 8?! are u ok lol

[@Brochesski]

@@eveyxp ngl probably not 😟😟

[@eveyxp]

@@Brochesski BLESS , just had a exam on this, half of the stuff that came up were shit i did in september 💔