CIE A Level Chemistry Solved Past Paper May/June 2018 P22

[@sakura.99_78]

Thanks A LOT for these videos , you made a level yearlys a whole lot easier so BIG TIME appreciation and respect

[@afrosweetness4597]

I HIGHLY APPRECIATE YOU MAKING THIS VIDEO, I HOPE YOU CONTINUE BEING OUR SAVIOUR. This revision for me was the best and not too long video which makes it soo much easier to sit through.

[@syedomer7733]

15:04 mr 284??

[@depresseddaemon914]

thank you so much! you've helped me alot... love from Malaysia💜

[@arsalahameed]

can't thank you enough for these videos, these are really helpful

[@manhaabdellah2682]

Thanks for making amazing videos. Id suggest you keep a marking scheme nearby so no technical terminology is missed. Formula mass is specifically for ions

[@madihamaysha9100]

for q2di, why did u multiply by 5? can u explain that part?

[@poly489]

13:51, why do we divide by the number of moles for iron only?

[@hafsashahid1088]

If you understood, pls tell me

[@vasundhara2274]

@@hafsashahid1088 multiply 39.2 with 10

[@sherbazriasat3087]

Maam u did a mistake in q.2.d)6.
Unhydrated mohr salt has Mr of 284, u wrote 108

[@examhelpweb2090]

Yes, you are right.

[@NiazManu]

Not enough explanation at all.

[@zainabishtiaq3668]

Fr

[@farzanaahmed8326]

For question 1 a shouldn't it be Mg + 2H2O __Mg(oH)2+H2

[@abdulhadiyaseen1288]

Isn’t reaction of Magnesium with cold water;
MG(OH)2 + H2?
Anyhow, really appreciate your help!!

[@examhelpweb2090]

Yeah it's H2 not H2O. Thanks for pointing that out.

[@abdulhadiyaseen1288]

@@examhelpweb2090 Thanks to you for putting great efforts!! 🙏

[@justArandomfellar]

@@examhelpweb2090 14:39 why is the Mr of anhydrous salt 108?? Can u plz explain.

[@mr-bean2306]

How you calculated Mr of unhydrated salt?

[@tantwh6474]

Mr=2x10^-3/0.784

[@zeeyadkhan4406]

(392-108)/18 does not equal 6 it equals 15.7, please explain

[@examhelpweb2090]

Oops! Mr of anhydrous salt is 284 so subtract that from Mr of hydrated salt and divide that by 18 to get 6. Thanks for correcting, I really appreciate that.

[@zeeyadkhan4406]

@@examhelpweb2090 Yes makes sense now, thanks for explaining, appreciated!

[@sultanskingo-_-2342]

15:35 , IS IT 25/2 or 12/2 and why? i got so confused on an easy question sorry.

[@onlyfornokia5250]

25/2 because O2 in the other side is 25 we need to balance it

[@sultanskingo-_-2342]

@@onlyfornokia5250 thank you

[@SameeraWalli]

please explain properly

[@damodarramdoyal5890]

Thank you

[@jawariazawaar3751]

Can you please explain question 2 last part

[@examhelpweb2090]

In order to get the value for x, you must at least know the Mr of water molecules that is present. To get that Mr, subtract the Mr of anhydrous salt from that of hydrated one. At last you now have the Mr of water that is present. Now to get the number of molecules of water present in the sample, divide the Mr of water by Mr of one molecule of water i.e. 18. Hope it is clear to you now.

[@jawariazawaar3751]

@@examhelpweb2090
Thank you Soo much 💞

[@baxtiyorduschanov3215]

0:38 if you do not balance the equation, do they give you a mark for only writing an equation?

[@examhelpweb2090]

Try to balance it because at most they may not give you the credit.

[@fawazkamran871]

Doing stuff wrong mr is 392-284 😂 14:58

[@tanatswadebwe8021]

thank you