GCSE OCR 21st Century Triple Science (CBP1-7) Thread

Reply 2360

Pandorax

11

Can anyone make a list of the math formula things we need to know? many thanks!

Reply 2361

Sulfur

OP

Original post by LouiseDB42

The dynamic equilibrium occurs as the chemical/compound/substance is constantly moving between the stationary and mobile phases. Depending on how soluble the compound is in the mobile phase and how attracted the compound is to the stationary phase influences the position of the dynamic equilibrium....so if a compound is very soluble in the mobile phase and not very attracted to the stationary phase it spends more time in the mobile phase and this means that it is carried further up the paper or has a shorter retention time (in gas chromatography) :smile:

Thank you very much! :smile:

Reply 2362

LouiseDB42

Original post by Sulfur

Thank you very much! :smile:

You're very welcome :smile:

that lovely paragraph was the result of today's marathon of a revision session at school!?

Reply 2363

Pandorax

11

My mnemonic for production chemicals
Max- starting Materials (feedstocks)
Saw- Synthesis
Piglet-separation of Products
With- handling Waste
Pooh- Monitoring purity

It's weird, I know.XD

Reply 2364

peacefully_

2

Original post by olmyster911

ALCOHOLS = -OH functional group. Think alcOHol :tongue:

~ reacts gently with sodium
~ used for solvents & fuels
~ ethanol soluble in water
~ ethanol is a good solvent
CARBOXYLIC ACID = -COOH functional group
~ react like other acids
~ can be tested for by reacting with carbonates & doing squeaky pop
~ they smell like rancid butter & sweaty socks
~ ethanoic acid is vinegar

Thanks

Reply 2365

username1344042

6

Can someone explain gas chromatography in note form please?? :s-smilie:

Reply 2366

katiemckkk

1

Original post by olmyster911

Can someone explain gas chromatography in note form please?? :s-smilie:

•

The mobile phase is the carrier gas

•

The stationary phase is the column

•

At the end of the column is a detector which detects when the substances reach the end

•

There is a recorder which is what records the data for the graphs that you get from gas chromatography

•

The time for a gas to move through the column is called the retention time

•

The graph shows the retention time and it also has peaks, these peaks show the quanities of the gases in the mixture

Hope it helped, anyone else feel free to add any more info :smile:

Reply 2367

katiemckkk

1

Links for june C7 paper??

Reply 2368

username1344042

6

Original post by katiemckkk

•

The mobile phase is the carrier gas

•

The stationary phase is the column

•

At the end of the column is a detector which detects when the substances reach the end

•

There is a recorder which is what records the data for the graphs that you get from gas chromatography

•

The time for a gas to move through the column is called the retention time

•

The graph shows the retention time and it also has peaks, these peaks show the quanities of the gases in the mixture

Hope it helped, anyone else feel free to add any more info :smile:

Thanks a lot! Just one thing..In my revision guide it says the stationary phase is oil? :confused:

Reply 2369

katiemckkk

1

Original post by olmyster911

Thanks a lot! Just one thing..In my revision guide it says the stationary phase is oil? :confused:

yeah sorry about that, the stationary phase is oil it's just packed into a column so I got confused but oil is right :colondollar:

Reply 2370

username1344042

6

Original post by katiemckkk

yeah sorry about that, the stationary phase is oil it's just packed into a column so I got confused but oil is right :colondollar:

I'm sticking with the column! My class notes say column too so I think you were right, at least partially :tongue:

Reply 2371

Sulfur

OP

Please be a nice paper tomorrow, but one that has low grade boundaries too... Come on!

Reply 2372

Fishhy34

5

the specimen paper was very hard :frown:

Reply 2373

Student.178

9

Could someone please explain chromatography to me in a simple way because my book is to detailed. Thank you. :smile:

Reply 2374

lyricalvibe

16

Can someone explain interpreting titrations? Just like the steps please? :smile:

LAST PAGE

Reply 2375

lyricalvibe

16

Original post by Fishhy34

the specimen paper was very hard :frown:

Can you link it please :smile:

Reply 2376

JasonBrown2K14

4

Original post by JazzyT17

Could someone please explain chromatography to me in a simple way because my book is to detailed. Thank you. :smile:

I'll summarise the notes in my guide - paper or gas?

Paper:

1 - Solvent moves up paper.
2 - Chemicals in sample dissolve and move between it and the paper. This sets up an equilibrium (where the two reactions are balanced).
3 - In the mobile phase, the chemicals move UP the paper FROM the baseline WITH the solvent.
4 - Before the solvent reaches the top of the paper, the paper is removed from the beaker.
5 - Different chemicals in sample form different spots on chromatography paper (usually it's filter paper). Chemicals that are in the mobile phase for longer from spots further up the paper (obviously - since they are moving for longer).

Any other problems (or if you want to know about gas chromatography or calculating the Rf values from chromatography) let me know and I can try to explain. I will try my best to help but I'm no C7 expert but I have been revising it for 2 days solid and explaining it helps me to understand too. :smile:

Original post by lyricalvibe

Can you link it please :smile:

There's two!

http://www.ocr.org.uk/Images/80682-unit-a173-02-chemistry-modules-c7-higher-accredited.pdf

http://www.ocr.org.uk/Images/137265-unit-a173-02-chemistry-module-c7-higher.pdf

(edited 9 years ago)

Reply 2377

Fishhy34

5

Original post by lyricalvibe

Can you link it please :smile:

http://www.ocr.org.uk/Images/80682-unit-a173-02-chemistry-modules-c7-higher-accredited.pdf

Reply 2378

Student.178

9

Original post by JasonBrown2K14

I'll summarise the notes in my guide - paper or gas?

Paper:

1 - Solvent moves up paper.
2 - Chemicals in sample dissolve and move between it and the paper. This sets up an equilibrium (where the two reactions are balanced).
3 - In the mobile phase, the chemicals move UP the paper FROM the baseline WITH the solvent.
4 - Before the solvent reaches the top of the paper, the paper is removed from the beaker.
5 - Different chemicals in sample form different spots on chromatography paper (usually it's filter paper). Chemicals that are in the mobile phase for longer from spots further up the paper (obviously - since they are moving for longer).

Any other problems (or if you want to know about gas chromatography or calculating the Rf values from chromatography) let me know and I can try to explain. I will try my best to help but I'm no C7 expert but I have been revising it for 2 days solid and explaining it helps me to understand too. :smile:

There's two!

http://www.ocr.org.uk/Images/80682-unit-a173-02-chemistry-modules-c7-higher-accredited.pdf

http://www.ocr.org.uk/Images/137265-unit-a173-02-chemistry-module-c7-higher.pdf

Thank you so much! :smile: