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National 5 Chemistry

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Original post by Ethan100
I scrolled up and found it :biggrin: Thanks so much


Aha its okay, chemistry is like the only subject I can do :smile::biggrin:
Original post by Ethan100
Eve I understand the picture you showed me but I am having difficulty knowing how to start. Im trying to do the 2015 15 b question


Okay lemme get it....
Reply 282
Original post by eve_4342
Hmmm... I don't know that stuff XD what about the extraction of metals from ores?


Dunno either lol
For titration calculations, In order for me to find an average I must only use the titre that are 0.2 cm^3 between each other right ?
Reply 284
Original post by Ethan100
For titration calculations, In order for me to find an average I must only use the titre that are 0.2 cm^3 between each other right ?


Yes the titre bit. Add the two then divide by 2
Original post by Ethan100
For titration calculations, In order for me to find an average I must only use the titre that are 0.2 cm^3 between each other right ?



use the 1st and 2nd titre, not the rough one!!!!
Original post by Ethan100
For titration calculations, In order for me to find an average I must only use the titre that are 0.2 cm^3 between each other right ?


IMG_2450.JPG
Original post by eve_4342
use the 1st and 2nd titre, not the rough one!!!!


I got the question correct by following your working :biggrin: THANKS

In order for a titration to be rough it must be o.2 cm^3 away from the other ?
In the 2015 paper it doesn't say rough titration it just says titration 1,2,3.

Oh and if the number of moles isn't 1 what numbers would I put in the equation ?
(edited 7 years ago)
Original post by Ethan100
I got the question correct by following your working :biggrin: THANKS

In order for a titration to be rough it must be o.2 cm^3 away from the other ?
In the 2015 paper it doesn't say rough titration it just says titration 1,2,3.

Oh and if the number of moles isn't 1 what numbers would I put in the equation ?


I would just use the 2nd and 3rd one to be on the safe side.
Where it says n1 or n2, put in the number of moles e.g if it was 2c6H12O6, the is 2 where the n would be instead of one.

Its fine!!!
Reply 289
Original post by eve_4342
I would just use the 2nd and 3rd one to be on the safe side.
Where it says n1 or n2, put in the number of moles e.g if it was 2c6H12O6, the is 2 where the n would be instead of one.

Its fine!!!


Do you guys use the c1v1 method?
This is how I work out the average

Titre 1 + Titre 2 then divide both by 2 and that's your answer
This is how I do titration questions, I find it the easiest method...

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how many marks are balancing equations worth and are they really important to know. Also what are the best things to learn if you are looking to scrape a pass would really appreciate it if someone answered thanks :smile:
Original post by Aston177
how many marks are balancing equations worth and are they really important to know. Also what are the best things to learn if you are looking to scrape a pass would really appreciate it if someone answered thanks :smile:


You may get a multiple choice question on balancing equations, or there may even be a question on it in section 2, You also need to know how to balance equations as part of a calculation.

If you want an easy 3 marks look at how to calculate the rate of reaction Unit 1 :smile:
Just a quick question... In titration questions the Volumes are in cm^3 I change it to litres when doing the question but do I change it back when I have an answer ?
Reply 295
Original post by Ethan100
Just a quick question... In titration questions the Volumes are in cm^3 I change it to litres when doing the question but do I change it back when I have an answer ?


Hmm good question. Dunno the answer.
Reply 296
Original post by Aston177
how many marks are balancing equations worth and are they really important to know. Also what are the best things to learn if you are looking to scrape a pass would really appreciate it if someone answered thanks :smile:


1 mark usually.

Learn Eh=Cm DeltaT - This is worth 3 marks
Learn =change in quanitity/change in time - Easy 3 marks
Mole calculations, So n=cv n=mass/gfm - Easy few marks
Original post by Jay431
1 mark usually.

Learn Eh=Cm DeltaT - This is worth 3 marks
Learn =change in quanitity/change in time - Easy 3 marks
Mole calculations, So n=cv n=mass/gfm - Easy few marks


@Aston177 Also learn percentage Mass calculations, another easy 3 marks
For the Eh=cmDeltaT m must be measured in kg right ? So I must change the units ?
Thanks so much for the help so far guys. I would like to ask when you are told to work out the gfm but are given the solution in words how do you find that out?

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