Higher Chemistry 2012-2013

OP

Why does chemistry have to be so bloody difficult?
Can someone help me please? :frown:

Consider the following two oxidations.
Fe2+ → Fe3+ + e-
Sn2+ → Sn4+ + 2e-
Which of these reactions is likely to take place in solution?

- Iron(II) ions will react with tin(II) ions.
- Tin(IV) ions will react with iron(III) ions.
- Iron(III) ions will react with tin(II) ions.
- Tin(IV) ions will react with iron(II) ions.

Reply 162

Original post by Nessie162

Why does chemistry have to be so bloody difficult?
Can someone help me please? :frown:

Consider the following two oxidations.
Fe2+ → Fe3+ + e-
Sn2+ → Sn4+ + 2e-
Which of these reactions is likely to take place in solution?

- Iron(II) ions will react with tin(II) ions.
- Tin(IV) ions will react with iron(III) ions.
- Iron(III) ions will react with tin(II) ions.
- Tin(IV) ions will react with iron(II) ions.

Think about the electrochemical series.

Reply 163

OP

Original post by Hype en Ecosse

Think about the electrochemical series.

Here I am pg 11 in the data book looking at the Electrochemical series and absolutely nothing is coming to my mind.

Iron is higher in the El. series than Tin.
I see it says that the reductions in the data booklet are going Solutions --> Solids. But I still don't know how to answer the question.
How do I know which reaction is likely to take place in a solution?

Reply 164

Original post by Nessie162

Here I am pg 11 in the data book looking at the Electrochemical series and absolutely nothing is coming to my mind.

Iron is higher in the El. series than Tin.
I see it says that the reductions in the data booklet are going Solutions --> Solids. But I still don't know how to answer the question.
How do I know which reaction is likely to take place in a solution?

Ah, have you not done the electrochemical stuff yet? Cells, half-cells, redox?

Basically, electrons flow "down" the electrochemical series. The most negative values for E^o give electrons to higher values. So you shove these 2 reactions into solution together, and it asks you what happens.

You have the two redox reactions from the question in the data book (just looked myself!), it's now just a matter of making sure you've got the equation the right way around, so you know what'll flow where. Remember, the most negative (or rather, the lowest) E^o gives up electrons!

Reply 165

OP

Original post by Hype en Ecosse

xx

We have. We finished the course.
They were probably doing this in class when I was off, because I don't remember learning anything about cells.
Thanks for help anyway.
I'll ask my teacher tomorrow to explain this to me in more detail. :smile:

Reply 166

Original post by Nessie162

We have. We finished the course.
They were probably doing this in class when I was off, because I don't remember learning anything about cells.
Thanks for help anyway.
I'll ask my teacher tomorrow to explain this to me in more detail. :smile:

If you want the answer, btw the reduction potentials of those reactions are:

Sn^{4+} + 2e^- \leftrightarrow Sn^{2+} \ \ E^o = 0.15V \\ Fe^{3+} + e^- \leftrightarrow Fe^{2+} \ \ E^o = 0.70V \\ \\

Reverse the equations to obtain the standard oxidation potentials: So Sn one = -0.15, Fe one = -0.70V. It goes from most negative to least negative, therefore it'd be Fe(III) reducing (reacting with) Sn(II). I might be mistaken, but I think that's right. :tongue:

If you're taking Chemistry at AH, cells and electrochemistry make a lot more sense there than they did at Higher.

Reply 167

OP

Thanks again.
Yeah, I'm taking Chem at AH, but I have no idea how I'm going to pass it if I'm struggling with the higher.
Hopefully you're right :biggrin:

I like things that make sense.
Is the AH much more difficult than the higher in your opinion?

Reply 168

CSM1996

14

I've finished the course also and I've never been off and I've never done cells... I've done redox but I've never noticed the E/V bit? I've never been taught anything about it, do I need to know what it is/does??

Reply 169

OP

I thought it was just me.
Now as I'm looking through my revision book it doesn't look like cells are a part of the higher course but then is there any other way to do the question I posted before?
This question was a part of Unit 3 practice NAB from scholar website.

Reply 170

StaciGA

We have FINALLY finished the course just in time for the Easter break! :biggrin:

I have never been so glad to finish a course in all my life! I have quite a strong dislike for chemistry, because I had a bad experience of it in Standard Grade. I JUST passed the prelim, like I got 53% which got me a C :/
That was with hardly any studying though, so I can't be that bad at it surely?

I really need to start studying this subject though. I tend to avoid it because of my dislike for it. It is very difficult though, which makes me avoid it even more.
Any ideas to encourage me to actually study this subject?
I would like to try and get an A, but I know that would require a LOT of work, but I really would like to prove my teacher wrong and do way better than she expects me to.

Reply 171

Original post by StaciGA

We have FINALLY finished the course just in time for the Easter break! :biggrin:

I have never been so glad to finish a course in all my life! I have quite a strong dislike for chemistry, because I had a bad experience of it in Standard Grade. I JUST passed the prelim, like I got 53% which got me a C :/
That was with hardly any studying though, so I can't be that bad at it surely?

I really need to start studying this subject though. I tend to avoid it because of my dislike for it. It is very difficult though, which makes me avoid it even more.
Any ideas to encourage me to actually study this subject?
I would like to try and get an A, but I know that would require a LOT of work, but I really would like to prove my teacher wrong and do way better than she expects me to.

I definitely don't think it's ever too late to turn things around, and think the only thing standing in the way of someone getting an A at Higher is the work involved.

Three things that you actually need to succeed:

1. Productivity
2. Motivation
3. Time

Productivity is simply being efficient and effective with your time. Don't spend 5 hours revising how to name hydrocarbons when you've known that **** by heart since Standard Grade - focus on things you don't know, struggle with or need to refresh; don't spend 2 hours reading through the textbook and just highlighting stuff. It's such a terrible way to learn. Don't sit and study while watching Spongebob Squarepants or whatever - distracted study is hardly study at all.

Effective study is easy, but people don't realise it. Always aim for understanding as opposed to memorisation wherever you can; don't use ineffective methods like reading over and over, or just copying out from the textbook. Actually do something active with the information. There's lots of information about studying EVERYWHERE. You just have to look for it.

Cal Newport's blog has a lot of information about studying, but you have to be careful because while there is a lot of good advice, there is a bit of pseudoscience as well. But it's a great place to start!

Lots of stuff on Reddit, but again, all completely subjective advice from non-experts; but lots of good advice in there. Maybe have a quick browse through /top/. More in the productivity /top/
There are even some superhumans out there, and there's no reason why you can't do that either. You'll be surprised just how much you can learn, and how massive your memory is.
http://www.youtube.com/watch?v=sbinQ6GdOVk
http://www.youtube.com/watch?v=K1ycE5Ydb3U

Motivation, it's up to you to find. Different things motivate different people, and there's lots on the internet about it. Go find yours and get cracking! You should relish the challenge! :biggrin:

Time is simple. Simply spend time studying; don't go too long without breaks; don't spend too much time on breaks; try to make studying part of your daily routine; don't leave it until the last minute; be consistent.

Reply 172

BigChimp

4

Original post by nerd434

For motivation, you more or less just want to type the likes of "Motivating Videos" into YouTube. Sure, the majority of the videos will be directed towards Black bodybuilders but the general message is always there... at least, it's always enough to spur me on for the time being.

"Black body builders" - that's gold right there.

This was posted from The Student Room's iPhone/iPad App

Reply 173

CSM1996

14

I need some help with a question, I'm not really sure how to go about it.

Use electronegativity values to describe the overall polarity of dichlorodifluoromethane molecules.

I know the electronegativity values but I am unsure how to go about it as it has 3 elements, C Cl and F, all the ones I've done previously have been two elements. Any help?

Reply 174

coultra1

Hi, I'm having some trouble with this question from 2008! I've tried it so many times that I just keep ending up in a huge muddle.. :P
It's from 2008, multiple choice question 35.

Equal volumes of 0.1mol/l solutions of the following acids and alkalis were mixed.
Which of the following pairs would give the solution with the lowest pH?
A. Hydrochloric acid and sodium hydroxide
B. Hydrochloric acid and calcium hydroxide
C. Sulphuric acid and sodium hydroxide
D. Sulphuric acid and calcium hydroxide

Thanks :smile:

Reply 175

CSM1996

14

Original post by coultra1

Hi, I'm having some trouble with this question from 2008! I've tried it so many times that I just keep ending up in a huge muddle.. :P
It's from 2008, multiple choice question 35.

Equal volumes of 0.1mol/l solutions of the following acids and alkalis were mixed.
Which of the following pairs would give the solution with the lowest pH?
A. Hydrochloric acid and sodium hydroxide
B. Hydrochloric acid and calcium hydroxide
C. Sulphuric acid and sodium hydroxide
D. Sulphuric acid and calcium hydroxide

Thanks :smile:

I think you need to work out which acid (HCL OR H2SO4) is the strongest out of them. Then for the alkali you need to work out whether sodium or calcium is the weakest. As if I'm right, strong acid + weak base = low pH.

Reply 176

ManicPumpkin

3

Hi!

I'm probably being thick (as per usual) but I do not get Higher 2012 Section A Q4

A solution of potassium carbonate, made up using tap water, was found to be cloudy.
This could result from the tap water containing
A sodium ions
B chloride ions
C magnesium ions
D sulphate ions.
(You may wish to refer to the Data Booklet.)

I cannot find anywhere in the Data Book that would help me with this question

Any help would be much appreciated! :-)

Reply 177

TheFOMaster

13

Original post by ManicPumpkin

Hi!

I'm probably being thick (as per usual) but I do not get Higher 2012 Section A Q4

A solution of potassium carbonate, made up using tap water, was found to be cloudy.
This could result from the tap water containing
A sodium ions
B chloride ions
C magnesium ions
D sulphate ions.
(You may wish to refer to the Data Booklet.)

I cannot find anywhere in the Data Book that would help me with this question

Any help would be much appreciated! :-)

Look up the solubility table on page 7 :smile:

The answers there :smile:

Reply 178

ManicPumpkin

3

Original post by TheFOMaster

Look up the solubility table on page 7 :smile:

The answers there :smile:

Ah I see! Thank you very much! :smile:

Reply 179