The NO3- and NO2 simply dont get involved right? Because the carbonate ion is CO3(2-) and you cant join together two negetively charged ion because of electrostatic repulsion. So because they aren't involved the NO3-, is just a spectator and NO2 is also still there
Hi, can someone explain the buffer question on the June 2012 paper, question 3c (ii) please? I get a pH of 4.12 when the mark scheme answer states 4.22 as the answer
Hi there, the way I worked this out was as follows:
Step 1: Simple, combining the 2 equations given as the copper is reacting with the HNO3.. so, u just balance and combine them, Cu(s) + 4HNO3(l) --> Cu2+(aq) + 2NO3-(aq) + 2NO2(g) + 2H20(l)
Step 2: It says that the sodium carbonate, is neutralised by any acid.. You should know that.. when acid + carbonate --> salt + CO2 + H20 So, I did.. NaCO3 + 2HN03 (as any acid, this was given so I used this- it makes no difference.. btw, u see I am writing out the equation first just to make it a bit easier to understand.. from the equation, u can then deduce the ionic equation), so NaCO3 + HN03--> Na(NO3)2 + C02 + H20
End point = point at which indicator changes colour (pH)
Equivalence point = point at which the number of moles of H+(?) = The number of moles of OH- (I think)
Okay thanks. I just did January 2013, and my ass was kicked. I need to mark it but Jesus christ, that was tough.
The level of questions has SIGNIFICANTLY gotten harder.
They through in so much AS-Stuff I had no clue about. Has anyone done it? It's going to be very hard to get an A* in Chemistry..... Jesus.
On Physics and Maths I'm finally after all my hard work scoring above 90's but Chemistry 5, whats going on, Chem is supposed to be my strongest subject.
January 2013 might have been the hardest thing I've ever done in my life. I had no clue what to do for Question 8. If they make another dumb paper like that one, I will literally fight someone.
Okay thanks. I just did January 2013, and my ass was kicked. I need to mark it but Jesus christ, that was tough.
The level of questions has SIGNIFICANTLY gotten harder.
They through in so much AS-Stuff I had no clue about. Has anyone done it? It's going to be very hard to get an A* in Chemistry..... Jesus.
On Physics and Maths I'm finally after all my hard work scoring above 90's but Chemistry 5, whats going on, Chem is supposed to be my strongest subject.
This Paper was so hard, thank you for taking the time to do this....think I should do some Maths and then mark this tomorrow can't stress over this for too long....
January 2013 might have been the hardest thing I've ever done in my life. I had no clue what to do for Question 8. If they make another dumb paper like that one, I will literally fight someone.
I took it in January... I got an E I was so gutted because I need a B for uni and I was so confident haha, it really kicked my ass! Hopefully this time it will be a lot easier!
This Paper was so hard, thank you for taking the time to do this....think I should do some Maths and then mark this tomorrow can't stress over this for too long....
I agree, it was a challenging paper! You're welcome, I'm glad that I can help! I'm guessing you've just done Jan 13 as a mock? You may have done better than you think! At least we have a difficult paper as a mock, it means we can see the type of stretch and challenge questions they can ask and learn how to tackle them I hope your revision is going well!
Hey Guys I just cracked redox titrations I was feeling the same helplessness and stress as you guys but now I love them. Personally I recommend everyone struggling with them to sit down with your teacher, personal tutor or even anyone you know who can help. What really helped me was going through it with someone step by step. I can't stress this enough. DRAW A DIAGRAMMATIC picture of whats going on EXACTLY. If the stem says ' 25cm^3 of solution was taken from the original sample of 250cm^3' DRAW IT IN YOUR diagram like an equation of whats going to what on a seperate sheet of paper show yourself that its been divided by ten so that when you get your moles you know to times it by ten to get you moles in 250 etc. I can't stress it enough about how important it is that you make it clear what the student in the question is doing. Once you do this it becomes so much easier. http://www.chemteam.info/Redox/WS-redox-titration-problems.html This site also has some really good questions which I feel were challenging enough to warm you up for exam questions. Hope this helps. AND GOING THROUGH IT WITH SOMEONE WHO KNOWS EXACTLY WHATS GOING ON IS EQUALLY IMPORTANT. I feel it's something that needs to be taught to you in great detail.
Now I have a problem myself. If anyone can show me some good note of what goes on in lattice enthalpy of hydration & solution questions I'd really appreciate it. I Just don't understand the concepts of why a metal higher then another in the group of the periodic table would have a higher lattice enthalpy of hydration. I thought it'd be the other way round. (This paragraph is probably is wrong in terms of the chemistry of it which shows how confused I am by the concepts).