Sir I know it may sound a bit silly but when would we typically use the coefficient in the equation? For example at 20:07 why didn't we need to use the 8? (since it's 8CO2) Whereas for the second part we had to use the ratio to find how much octane burnt. Also for 24:09 I worked out the volume of butane first and then multiplied by 3 to work out the volume of ethene and then added them together to find the total volume. (The multiplied by 1000000 to get it in cm3) I got the same answer as you but typically for an exam question would it be better to do it how you did it by adding up the moles first or is how I did it fine? I know there's multiple ways of getting the right answer and as long as we remember that the question is asking for total volume that's the most important part but I'm just paranoid of getting answers wrong just in case this isn't the safest option.
@nishatjeonkim2096 hi, thanks for thinking so carefully about the video. Two really good questions 👏 Firstly, we use the coefficients in questions like this when we are working out the moles of one chemical using the moles of one of the others - using the ratios from the equation. So since for part 1 we used the idea gas equation to work out moles of gas then we don't use the 8. Then when working with octane we used moles of CO2 to work out moles of octane and needed the equation to do this. 2) your way is just as good and gets the same number of marks. I think the way I showed is maybe a little faster, but you should use the method that works best for you 😃
Thanks for the video. This question is slightly unrelated to the video. I was wondering what ""room temperature and pressure " is. Online, I get find different values for pressure = 100,000 Pa or 101,000 Pa and room temperature varies = 20 or 25 degrees. I was wondering which is correct for the AQA exam board for A-level chemistry ?
So for Room temp and pressure (RTP) it's 20, Standard Temp and Pressure is 25. STP is used much more than RTP. Pressure is the same for both and is simplified to 100kPa. Its true value is 101kPa but the precision is unnecessary.
Hi there, I think you're correct! When I made this video, I must have calculated with temp of 371K I think, instead of 317K. That's the only way I get 0.328. This obviously affects the mass too!
(1) I was confused why you used the R constant of 8.31 with Pa instead of kPa, but it seems like that's correct when using volume in meters cubed? I've only ever seen volume in liters on these types of questions but that doesn't mean that I won't on the exam. Is there a chart somewhere that lists every possibility of units to R constant? The cm and m cubed for volume is also new for me. (2) Do you have a video on unit conversions?
1) for the ideal gas equation you usually use the SI units for each quantity. 2) I've not got a unit conversion video actually- I weave it in to the topic videos when they come up really
Hi, yes, this video will be suitable for any exam board. I teach AQA so I always make sure it covers everything needed for AQA. All exam boards are at least 95% the same though. The main differences between them is not the content they include, but rather how they structure the course, what topics are on each exam and the question style
YOU ARE AMAZING SIR!! GOD BLESS YOU. Please continue what you are doing!!
Thank you for the lovely feedback. 😍 glad it was useful 👍
Was the answer wrong at 20:09? Because I used the same formula with the same units and got 0.741, not 0.0741.
Yes indeed, good spot! 👍
I added an extra zero for my answer
Such an excellent teacher with clear explanations, thank you sir.
You're very kind! I'm glad it's useful 😊
Really like your videos still helps me after 4 years of it being made😊, thank you
Thanks for watching and for the wonderful feedback! 😃
May God bless you, Sir! You’re the best!
Thank you for your kind words! It's really lovely to know that the videos are useful 😀
Sir I know it may sound a bit silly but when would we typically use the coefficient in the equation? For example at 20:07 why didn't we need to use the 8? (since it's 8CO2)
Whereas for the second part we had to use the ratio to find how much octane burnt.
Also for 24:09 I worked out the volume of butane first and then multiplied by 3 to work out the volume of ethene and then added them together to find the total volume. (The multiplied by 1000000 to get it in cm3) I got the same answer as you but typically for an exam question would it be better to do it how you did it by adding up the moles first or is how I did it fine? I know there's multiple ways of getting the right answer and as long as we remember that the question is asking for total volume that's the most important part but I'm just paranoid of getting answers wrong just in case this isn't the safest option.
@nishatjeonkim2096 hi, thanks for thinking so carefully about the video. Two really good questions 👏
Firstly, we use the coefficients in questions like this when we are working out the moles of one chemical using the moles of one of the others - using the ratios from the equation. So since for part 1 we used the idea gas equation to work out moles of gas then we don't use the 8. Then when working with octane we used moles of CO2 to work out moles of octane and needed the equation to do this.
2) your way is just as good and gets the same number of marks. I think the way I showed is maybe a little faster, but you should use the method that works best for you 😃
Thanks for the video.
This question is slightly unrelated to the video. I was wondering what ""room temperature and pressure " is. Online, I get find different values for pressure = 100,000 Pa or 101,000 Pa and room temperature varies = 20 or 25 degrees. I was wondering which is correct for the AQA exam board for A-level chemistry ?
So for Room temp and pressure (RTP) it's 20, Standard Temp and Pressure is 25. STP is used much more than RTP.
Pressure is the same for both and is simplified to 100kPa. Its true value is 101kPa but the precision is unnecessary.
Thank you @@chemistrytutor
hey sir i think you made a mistake at 18:07 because it should be 0.038mol
Hi there, I think you're correct! When I made this video, I must have calculated with temp of 371K I think, instead of 317K. That's the only way I get 0.328.
This obviously affects the mass too!
@@chemistrytutor and again at 20.07. It should be 0.741moles not 0.0741moles
@@07MurphyTricia Great spot, thank you for pointing this out for everyone 😀
@@chemistrytutor thank you
in 24:10, it says in the gas equation the mol is 0.8 not 0.2, so the answer should've been 6839.13cm cubed?
Thanks for tje question. I used 0.8 in the ideal gas equation for n, so the answer I got is correct in fact 👍
@@chemistrytutor ahh okay, thank you so much for replying and your videos are heaven-sent. I’m even starting to enjoy chemistry now. God bless 💖
@@ali7ah that's lovely to hear! Well done for sticking at it!
(1) I was confused why you used the R constant of 8.31 with Pa instead of kPa, but it seems like that's correct when using volume in meters cubed?
I've only ever seen volume in liters on these types of questions but that doesn't mean that I won't on the exam. Is there a chart somewhere that lists every possibility of units to R constant? The cm and m cubed for volume is also new for me.
(2) Do you have a video on unit conversions?
1) for the ideal gas equation you usually use the SI units for each quantity.
2) I've not got a unit conversion video actually- I weave it in to the topic videos when they come up really
@@chemistrytutor so that would be meters cubed, Pa, moles, and Kelvin?
@@marigeo24 exactly 💯
Sir 18:04 isn't the answer wrong? Shouldn't the answer be 0.038 mol?
You're absolutely right, good spot! 😃
I've clearly typed the wrong value into the calculator. This has had a knock on effect on the Mr value too!
Thank you so much sir
Very welcome! Glad it's useful 😊
Hi, I do Edexcel a level chemistry. Can I still use your videos?
Hi, yes, this video will be suitable for any exam board.
I teach AQA so I always make sure it covers everything needed for AQA.
All exam boards are at least 95% the same though. The main differences between them is not the content they include, but rather how they structure the course, what topics are on each exam and the question style