Hi guys, just some quick question. For a mass spectrum. if we were to put down/ give a fragment, would it be incorrect to represent say C02H+ as CH02+ ? Hope that makes sense. If so why? Thanks
Hey, could someone please just check my thought process is correct.
When a redox reaction produces a solid, the equilibrium moves to the right (so the constant increases) so the value for the cell's emf will increase? Which explains why, despite a negative Ecell, it could still occur?
That's right, though, I'm not sure whether it is the equilibrium constant or the reaction coefficient that is affected by the equilibrium shift. (I thought the equilibrium constant is only affected by temperature?)
And I think it's suitable to say the cell's emf increases and becomes positive?
I think the answer is B (for the parent ion peak at least) because the RAM of bromine is 80, this however is an average resulting from the mass of the two most common stable isotopes of Bromine; one being Br-79, and the other being Br-81. Br-80 is much less common and only has a half life of about 18 minutes so it won't appear in the mass spectrum. Therefore there will be one peak for the bromoethane with Br-79 in it (29 + 79 = 108) and one peak for the bromoethane with Br-81 in it (29 + 81 = 110).
Woah! Thanks!
In normal Mr calculations, we are supposed to use 80/79.9 for bromine, unless specified otherwise right?
That's right, though, I'm not sure whether it is the equilibrium constant or the reaction coefficient that is affected by the equilibrium shift. (I thought the equilibrium constant is only affected by temperature?)
And I think it's suitable to say the cell's emf increases and becomes positive?
But the top position could be any group, could rotate ring until different top position, im sure there is a method for choosing the start number?
I think they actually use a different naming system that we don't learn about using: 'ortha' for adjacent substituents (eg 1,2) 'meta' for being next door but one (eg 1,3) 'para' for opposite substituents (eg 1,4)
Luckily we don't have to learn this though and hopefully they won't mind what number we use.
Hi mate, I was wondering how is it all going and what are your plans for chemistry. What are you aiming for? What do you need to get the grade? If you did unit 1, how did it go?
Can't find a unit 4 thread but does anyone know how to work out question 21(a)(ii) in edexcel unit 4 January 2012 paper? It's about orders of reaction and initial rate... The mark scheme doesn't explain how to get the answer.
Can't find a unit 4 thread but does anyone know how to work out question 21(a)(ii) in edexcel unit 4 January 2012 paper? It's about orders of reaction and initial rate... The mark scheme doesn't explain how to get the answer.
I haven't done unit 4 since the Jan exam but I'll give it a go. You work out in a)i) that k = 1.03 x 10-4 Then since you are given the rate equation: rate = k[CH3CH2Br][OH-] And you know that the concentration of both reactants is 0.02, you can just sub everything in to find out the initial rate: rate = (1.03 x 10-4) x (0.02) x (0.02) = 4.1 x 10-8 moldm−3s−1
I haven't done unit 4 since the Jan exam but I'll give it a go. You work out in a)i) that k = 1.03 x 10-4 Then since you are given the rate equation: rate = k[CH3CH2Br][OH-] And you know that the concentration of both reactants is 0.02, you can just sub everything in to find out the initial rate: rate = (1.03 x 10-4) x (0.02) x (0.02) = 4.1 x 10-8 moldm−3s−1
Can someone explain how to work out the answer for this? answer is D but how, i thought sodium carbonate gets rid of acid impurities, and i havnt come across sodium sulphate as a drying agent
Can someone explain how to work out the answer for this? answer is D but how, i thought sodium carbonate gets rid of acid impurities, and i havnt come across sodium sulphate as a drying agent
It's anhydrous sodium sulphate as it says in the question stem.