A-level Chemistry tutorials following the OCR (A) specification but suitable to most UK exam boards. Some videos in collaboration with Ashton Sixth Form College (ASFC Chemistry), Greater Manchester. I’m also on TikTok as @mrmurraygreen as of September 2022!
Check out the Google sheet with all my videos organised by module in the links below!
For all buffers calculation, which is more beneficial for me to memorize, the formula of Ka=HA/A- or Henderson-Hasselbatch relationship. I find it easier to use Henderson relationship but only WHEN question is asking for pH but what about for all types of question?
I’ll be honest in that I have been teaching this for 16 years and personally never found any worthwhile value in learning the Henderson Hasselbatch equation 🤷♂️😆🔵
@@mrmurraygreen Haha thanks Sir now that equation is carved in my brain sadly… Trying to remember the other one but why won’t formula be same for buffers and weak acid? Why does weak acid one have square root and the other no?
03:30 "completes" the circuit from what i understood, even without the salt bridge there's flow of electrons for some time but not for long. So the salt bridge kinda extends the duration of flow of electrons by balancing the net charge on both sides of the cell with the transfer of Ions as you said. So basically the salt bridge keeps the current in the circuit flowing and doesn't "complete" it right? I have a feeling what I understood is somehow wrong. Thanks btw you're helping me so much for my exams.
I disagree. It helps maintain the flow of the electrons and prevents the process stopping short very quickly. Without it , things would grind to a halt so we describe it this way. Thanks for watching and I’m glad the videos are useful! 🔵
Hi Sir, I've just recently discovered this channel and it's the most helpful resource for me right now. I want to make an application to Oxford to read chemistry soon and was wondering if there are any specific videos on this channel that dive into extra detail on any topic compared to what the exam spec says? I'm aware in interviews they like to extend far beyond it. Thank you!
Hello I have a question: for a heterogenous equilibrium like CaCO3(s) <--> CaO(s) + CO2(g), I know Kc = [CO2]. But we are told that Kc is temperature dependent and changing concentration doesn't affect Kc. Why doesn't the Kc change if we add in CO2 for example, increasing [CO2], if its proportional to Kc? I'd appreciate a detailed answer on this, thanks in advance Mr Murray! :)
Remember that the other species are still present in the vessel even though they aren’t in the Kc expression. They are only excluded because their concentrations are very high. So when you introduce more of a chemical, the chemistry of the reaction still happens and those large concentrations will still be involved in the shift required to restore the Kc back to its original value.
This is such a random question, but can you do a tattoo tour, I occasionally see your tattoos and they looks so interesting. Sorry for awkward question.
Hey 👋 I like this idea! Although they have a mix of stories (or total lack of story) behind them 😅 I’m getting a new one in Sept, I’ll do a montage once I’ve had that one added 🔵
in school i was taught that the lone pairs also are contributing to the chiral centers, so the NH(secondary amine) has a lone pair with 3 different groups, so it is a chiral center, if this thin is true then tertiary amine also has a lone pair, in total having 4(in the video) + 2 = 6
Hi, an excellent question! Pyramidal nitrogens which are bonded to 3 different groups (whilst still having a lone pair), e.g. amines like you mentioned, are classed as achiral as they invert their own shape at RTP back and forth between their own isomers. Therefore we do not include them in the count. If we were able to create conditions where the inversion doesn’t happen then we would include them.
Z and cis are not mutually exclusive (neither are cis and trans) here is some more guidance = ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-kK1X2b6CHKE.htmlsi=ysmM0gei_9RIEb-t
When I asked my teacher how to dicipher skeletal structure she explained it in a way where all I heard was "Hydrogen... Something, something, something... Hydrogen and something else..." This video helped so much. To be fair im only in year 9 but I want to know advanced science early to make it easier for myself in Biology and Chemistry A Levels in 2 years time.
Hello prof. Your teaching is excellent and really helps me understand the material. It would be great if you could upload longer videos soon for more in-depth teaching
Hello prof. You teach Chemistry very well you deserve millions of subscriber and millions of views and I am wondering if you have uploaded the lecture on atomic structure. Thanks!"
Hello, thanks for the feedback, and I’m sorry but I’m not sure what you’re referring to? I don’t remember saying I would be uploading a lecture on atomic structure?
@@mrmurraygreen I hope you're doing well. I wanted to ask if you have uploaded the lecture on atomic structure. I couldn't find it in the course materials and wanted to make sure I haven't missed it. If not, could you please upload it?
@@mrmurraygreen I wanted to ask if you have also uploaded the lecture on the wave properties of radiant energy and the electromagnetic spectrum. "Thanks for your time and assistance"
I got an E in my chemistry mock in January ever since then started watching ur videos and I honestly feel so good finishing my chemistry A-level with a smile mostly thanks to you ❤!
A 5 marker on making a standard solution came up in the unified paper today and it was almost exactly the same as this one! Thank you so much sir for all your videos, you helped me get through a level chemistry this year 😊
Hi sir, I haven’t commented before but I just want to let you know I watched this video this morning 20 minutes before the exam. I’ve never ever gotten an NMR question right but a very similar question came up and I’m confident I’ve done it well. Thank you.
Thank you for the video! I have a question: why do carboxylic acids, esters and amides not react with 2,4 DNHP and form an orange precipitate even if they do have the C=O bond?
Good question! Its position on the chemical shift scale and the very distressed splitting it has doesn’t follow a clear ‘roof’ shape like other peaks do. (i.e. other peaks go to a point in the middle using their splitting pattern)
I see your request and raise you 2 videos on this very topic! ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-GsaEmkw__1Q.htmlsi=BEpWUVK711rqy9n2 ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-kk2Xappp8NI.htmlsi=LWAg_oCoQJxYQ74R
Hey sir wouldn't there be 5 proton environments in total as the cooh signal is missing from the nmr? So would the final structure only have 5 proton environments? I know I am wrong but wasn't sure why.
Hi at 8.39. If you put peak at 2.4ppm quartet and 3 neighbouring but only put CH2 instead of ch3-ch2-co is that still considered correct or do you need the full structure at 2.4ppm to get the mark if that makes sense thanks
Edited! Sorry my initial reply misread what you asked! You should always show the immediate other section of the molecule that the peak you are analysing is bonded to. Use the chemical shift scale to identify possible functional groups and the splitting pattern to identify other H’s. That way I am able to say it’s not just a CH2 but instead a CH3-CH2-CO! Does that make sense? Does that answer your Q?
@@mrmurraygreenwanted to double check if you could get the mark without it. Because on some mark schemes the ch2 for example is in bold and the neighbouring aren’t. Sometimes I struggle with the neighbouring assignment and just the ch2 which would be in bold in the mark scheme but would that get you the marks e.g if it was for 4 marks and 1 mark represented one chemical shift analysis
@@mrmurraygreenif I’m stuck on what the neighbouring is would it be best to put the ch2 only which in mark schemes are bold or try and guess the neighbouring assignment . Cause for these they are usually 6 marks and 4/6 according to my teacher is for analysis for the nmr and since I stuggle with the final structure I am happy with getting the 4 analysis marks thanks
The bit in bold is the mark scheme’s way of showing what part of the molecule is responsible for the peak you are reporting on. You need to try and include the stuff around it to get the full analysis marks. Here are some general tips: How many H’s are in a peak comes from the relative peak area You can determine what functional groups it is bonded to based on its chemical shift data. Then you know how many H’s are on the next carbon(s) up based on the splitting pattern (and the n+1) rule. If you would like more practice with NMR then check out the year 2 playlist on my channel as there are lots of NMR tutorials in there.
@@mrmurraygreen thanks and one more questions if you get everything correct like all the analysis and attempted final answer but get it wrong how many marks can you get if it’s a six marker
Thanks 🙏🏻 There are lots in my Unified Chemistry walkthroughs playlist and in the level of response playlist already but I am always looking for feedback and this is a great suggestion. Perhaps a summary video before paper 3?!
