GCSE OCR 21st Century B7 C7 P7 - W/C - Monday 20th June 2016

PM me your email address and I will try and send some P7 resources to you. I dont own them btw!.

Does anyone have any tips for remembering information (e.g functional group, properties, reactivity etc) about alkanes, alkenes, carboxylic acids and esters? It would be greatly appreciated, seen as I'm worried I'll get mixed up in the exam

Our teacher taught us a mnemonic for remembering how many carbon atoms are in the chemicals. It goes like this, Monkeys Eat Peanut Butter. M - one carbon atom E - two carbon atoms P - three carbon atoms B - four carbon atoms

For example Methane comes under monkey and contains only one carbon atom. Whereas Butane contains 4 carbon atoms. For alkanes, these are surrounded by hydrogen atoms and so once you know how many carbon atoms are in them, the rest is simple! This also applies to alcohols and carboxylic acids.

Thanks!

Hey guys! im in this absolute g's class too. i like p7 interesting topic, just wish there were more past papers we can try on.

Who's the G ? Mr. Cowen ?


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oh i mean im the op's class and school. i dont know who mr. cowen is - but our science teacher is pretty alright too!

Got 100UMS on C7 AMA

Do you have any advice on this exam and do you have any ways to remember how to draw esters as I struggle with this. Thanks

My method for naming/drawing esters:

In the name, you put the alcohol first and the carboxylic acid second. A comes before C in the alphabet, so this makes sense.

For the drawing, it's the inverse. You want to start with drawing the carboxylic acid part first (on the left hand side), then the alcohol.

I'll give you a worked example. The question says draw the ester formed when butanoic acid is heated with ethanol (with an acid catalyst ). Firstly, name the ester (ethyl butanoate). Then start by drawing 4 carbons, draw the relevant hydrogens on the first 3 carbons, then the double bond with oxygen and the single bond with oxygen. Then attach to the other end of the oxygen that is single bonded the first carbon from the ethanol, and then the second carbon afterwards.

Remember also that water is formed in this reaction as you lose a H+ from the carboxylic acid, and an OH- from the alcohol, which react together to form H2O.

Thanks, this is really helpful. Please may you also do stuff to do with titrations as this seems complicated?

okay do you do moles in C7 or C6? I can't remember.

My method for naming/drawing esters:

In the name, you put the alcohol first and the carboxylic acid second. A comes before C in the alphabet, so this makes sense.

For the drawing, it's the inverse. You want to start with drawing the carboxylic acid part first (on the left hand side), then the alcohol.

I'll give you a worked example. The question says draw the ester formed when butanoic acid is heated with ethanol (with an acid catalyst ). Firstly, name the ester (ethyl butanoate). Then start by drawing 4 carbons, draw the relevant hydrogens on the first 3 carbons, then the double bond with oxygen and the single bond with oxygen. Then attach to the other end of the oxygen that is single bonded the first carbon from the ethanol, and then the second carbon afterwards.

Remember also that water is formed in this reaction as you lose a H+ from the carboxylic acid, and an OH- from the alcohol, which react together to form H2O.

I don't remember doing them at all?

I've looked up on a couple of websites and they all say that the carboxylic acid loses the OH and the alcohol loses the H to make H20??