Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
****Leaving Certificate Chemistry [All Levels] Before and After Discussion****
Options
Comments
-
-
Hi guys,
I'm going to have to cram desperately tonight, as I've neglected this subject completely.
If you were to advise me to study four experiments, what would they be? What other sections should I definitely cover in the limited time I have left? I'm definitely not doing Q8 so anything besides that.
Thanks!
Ammonium iron II sulphate titration, iron tab tirtation (basically all of the theory is the same so half the learning
)
Ethene , soap
Rates of reaction titration with H2O2 and MnO2
(I know that's five but :pac: )
If I were you I'd learn equilibrium and rates of reaction, oftern get a question to a question and a half on these two topics and have a glance over fuels.
If anyone has better predictions for the experiments, feel free to contradict me, I haven't spent much time analysing what has come up what year with chem :pac:0 -
The bonding, trends and history chapters always come up. Have you all your titrations learned? They shouldn't take more than 30 minutes to learn if you don't. Besides that I'd say soap, ethene/ethyne, and the two rates of reactions experiments.
I got full marks in Q5 in the mocks and that, Q4, and Q1 are the only ones I like really.
I like the titrations as I'm good at the maths side, but I never know the colour changes. Is there any place with all the colour changes for our titrations? Our teacher gave us a copy before but I'm sure I've lost it.
I'll definitely be doing the following Qs, so any specific tips would be appreciated. Q1,4,5,6,7. Then I'll have to do another experiment Q and in the mocks the remaining Qs I did were just a matter of picking the best of a bad lot (and avoiding Q8) so if I could cover anything tonight that'd cover me for another question I'll do that.0 -
I got full marks in Q5 in the mocks and that, Q4, and Q1 are the only ones I like really.
I like the titrations as I'm good at the maths side, but I never know the colour changes. Is there any place with all the colour changes for our titrations? Our teacher gave us a copy before but I'm sure I've lost it.
I'll definitely be doing the following Qs, so any specific tips would be appreciated. Q1,4,5,6,7. Then I'll have to do another experiment Q and in the mocks the remaining Qs I did were just a matter of picking the best of a bad lot (and avoiding Q8) so if I could cover anything tonight that'd cover me for another question I'll do that.
Methyl orange = Yellow to red.
Phenolphthalein = Pink to colourless
Any of the manganese titrations = Colourless to faint permanent pink.
EDTA titration = Wine red to blue.
Bleach = Reddish brown to pale straw yellow, then add starch indicator and it's blue-black to colourless.
I can't remember the winkler method one off my head
could he another starch one. 0 -
-
Advertisement
-
-
-
Methyl orange = Yellow to red.
Phenolphthalein = Pink to colourless
Any of the manganese titrations = Colourless to faint permanent pink.
EDTA titration = Wine red to blue.
Bleach = Reddish brown to pale straw yellow, then add starch indicator and it's blue-black to colourless.
I can't remember the winkler method one off my head could he another starch one.
Winkler is same as starch at end but few steps before that. Add drops of MnSO4 and Winkler reagents (Ki + NaOh) to get a white precipitate. If oxygen is present this will then form a brown precipitate. Add sulfuric acid to liberate iodine (reddish-brown) which undergoes same colour change as iodine in bleach.0 -
Winkler is same as starch at end but few steps before that. Add drops of MnSO4 and Winkler reagents (Ki + NaOh) to get a white precipitate. If oxygen is present this will then form a brown precipitate. Add sulfuric acid to liberate iodine (reddish-brown) which undergoes same colour change as iodine in bleach.
This was question 1 last year though wasnt it
Okay so im really looking for an A1 in Chemistry, and im good enough at it but ive really been slacking on the study be ause i feel i know stuff well enough already.. Whats everyone focusing on tonight and in the morning 0 -
jellytots95 wrote: »This was question 1 last year though wasnt it
Okay so im really looking for an A1 in Chemistry, and im good enough at it but ive really been slacking on the study be ause i feel i know stuff well enough already.. Whats everyone focusing on tonight and in the morning
Yeah I was just clarifying in case, and it could always come in section b as part of a water question this year! I feel the same about wanting an A1 but slacking lately. Current plan of attack is to go cover to cover in the textbook and anything I know well I'll just glance at, if I don't know something I'll make notes and see if it males sense. This kind of startegy helped in other subjects because you catch a lot of weird details which are omitted in general study and which examiners love to bring up. 0 -
Advertisement
-
-
-
-
-
-
-
-
-
-
-
Advertisement
-
-
-
-
-
-
-
little sis... wrote: »Thanks is that always how to check if something is polar/ soluble in water? We were just told to remember that v shaped and pyramidal make it polar/soluble in water.
And would it not make it very slightly polar ?
You find the difference between the electronegativity values and if it's less than .4 it's a non-polar compound.
I don't think it matters what you say regarding it's non-polarity/polarity if it's that close to .4, it'd probably be best to say it has negligible polarity now come to think of it. We looked at something in a marking scheme before with a similar electronegativity difference and I'm fairly sure they gave it to you whether you said slightly polar or slightly non-polar.
We did it the electronegativity difference way, I personally haven't heard of your way of doing it and it doesn't say it anywhere in our book as far as I can see :P0 -
You find the difference between the electronegativity values and if it's less than .4 it's a non-polar compound.
I don't think it matters what you say regarding it's non-polarity/polarity if it's that close to .4, it'd probably be best to say it has negligible polarity now come to think of it. We looked at something in a marking scheme before with a similar electronegativity difference and I'm fairly sure they gave it to you whether you said slightly polar or slightly non-polar.
We did it the electronegativity difference way, I personally haven't heard of your way of doing it and it doesn't say it anywhere in our book as far as I can see :P
Okay that's what I had originally thought but our teacher told us the shape of the molecule determines it's polarity :rolleyes: Thanks 0 -
little sis... wrote: »Okay that's what I had originally thought but our teacher told us the shape of the molecule determines it's polarity :rolleyes: Thanks
Maybe it does but I just never heard of that method
No bother 0 -
Advertisement
-
Advertisement