Year 12s: what will be the first way you research your future options? >>

IGCSE CHEMISTRY 2013 (May 20th & June 10th)

Scroll to see replies

Yep those are the exact titration calculations: what is the concentration of..... what is the volume of ..... etc.

They're so solid. Like diamond solid.

Reply 101

Enigma Machine

Original post by tw15st3d

when you say titrations, what exactly are the types of question you are referring to? i.e. ones tod o with mol/dm3 and you have to work out the concentration of something else??

Yup; you set it up to find out quite accurately how much of one solution to react with another (usually acid-alkali)

Original post by amalik_

Any notes on making salts would be appreciated because I'm still a bit confused about them, thanks!

Posted from TSR Mobile

I still find making salts a bit complicated, but here goes.

You need to know whether the salt will be insoluble or not and should therefore know off by heart that:
1. All salts of potassium and sodium are soluble
2. Ammonium salts are soluble
3. All nitrates are soluble
4. All chlorides are soluble except silver chloride
5. All sulfates are soluble except barium sulfate and calcium sulfate
6. All carbonates are insoluble except sodium carbonate, potassium carbonate and ammonium carbonate (refer to 1 and 2)

Method:
1. Mix together the two soluble salt solutions
2. Allow to react and filter to separate the precipitate
3. Wash with distilled water to remove one of the solutions (reaction dependent)
4. Dry it

The aim is to use two soluble salt solutions to make something that is NOT soluble; the precipitate. Try to see the link - the salts react and you want to end up with something insoluble.

Original post by Jake97

can somebody explain cracking (thermal and catalytic) in great detail please? And the precise conditions please

The purpose of catalytic cracking is to make long alkanes into shorter alkanes; usually because the supply of short alkanes is a lot smaller than the demand but the supply of long alkanes is a lot higher than the demand.
Conditions:
A temperature of 600-700 degrees C
A catalyst of either aluminium oxide (alumina) or silicon dioxide (silica)

(edited 10 years ago)

Reply 102

Enigma Machine

Original post by dathtom

How about the entire course??? Pretty Please :please:

No can do broski

edit: electrolysis notes incoming! (photos, as requested by Olympiad)

(edited 10 years ago)

Reply 103

username877577

Original post by Bude8

No can do broski

edit: electrolysis notes incoming! (photos, as requested by Olympiad)

Also, if you look at my visitor posts on my profile Bude posted notes there too!

Posted from TSR Mobile

Reply 104

Enigma Machine

Original post by Olympiad

QFA

Electrolysis:

Spoiler

Reply 105

username877577

Original post by Bude8

Electrolysis:

Spoiler

Thank you so much!

Posted from TSR Mobile

Reply 106

Enigma Machine

Original post by Olympiad

Thank you so much!

Posted from TSR Mobile

np, sorry my handwriting/the photos aren't brilliant!

Reply 107

amalik_

Thanks so much for your replies about the salts they're really helpful :smile:

Posted from TSR Mobile

Reply 108

amalik_

Hi guys could someone please please explain to me just one part of titrations calculations? I can do it all except for the final part on question 6)d)iii on the sample assessment material? In the answers I don't get why you have to times it by 1000 not divide by 1000. Thanks so much any help would be appreciated :smile:

Posted from TSR Mobile

Reply 109

Scruff the cat

Original post by Olympiad

I zinc that joke is so funny my tummy hertz

Posted from TSR Mobile

I was going to tell you a joke about sodium and hydrogen but NaH :cool:

Reply 110

Theabsolutelad

Does anybody have any idea of the grade boundaries? I know that this is a new syllabus but aqa is usually around 80%

Reply 111

Enigma Machine

Original post by Theabsolutelad

Does anybody have any idea of the grade boundaries? I know that this is a new syllabus but aqa is usually around 80%

Roughly 140/180

Reply 112

alexgr97

Can someone quickly tell me the official colours in acid, alkali and neutral solutions for:

1) Universal indicator
2) Methyl orange
3) Phenolphthalein

Thanks!

Reply 113

Enigma Machine

Original post by amalik_

Posted from TSR Mobile

Just had a look. You don't times by 1000, you are meant to divide by 1000.

Reply 114

Enigma Machine

Original post by alexgr97

Can someone quickly tell me the official colours in acid, alkali and neutral solutions for:

1) Universal indicator
2) Methyl orange
3) Phenolphthalein

Thanks!

2. Acid - red, alkali - yellow

3. Acid - colourless, alkali - pink

Reply 115

username877577

Original post by Scruff the cat

I was going to tell you a joke about sodium and hydrogen but NaH :cool:

watt, so unfair!
All the good jokes argon anyway,
Physics jokes on the other hand have potential...

Reply 116

Enigma Machine

Original post by Olympiad

watt, so unfair!
All the good jokes argon anyway,
Physics jokes on the other hand have potential...

Is Silicon the same in Spanish?

Si

Reply 117

username877577

Original post by Bude8

Is Silicon the same in Spanish?

Si

It's Silicio I think, why?

Posted from TSR Mobile

Reply 118

Enigma Machine

Original post by Olympiad

It's Silicio I think, why?

Posted from TSR Mobile

What's the chemical formula for silicon? Check again and then look at my post :smile:

Reply 119

username877577

Original post by Bude8

What's the chemical formula for silicon? Check again and then look at my post :smile:

oooh sorry, thought you were asking what it was in Spanish - our teacher showed us this periodic song in Spanish lool 'twas catchy,

Yeah it's Si!

Posted from TSR Mobile