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

OP

Original post by olmyster911

No don't say that omg

To be honest, there hasn't been much in the way of maths in the papers this year (besides the P1-3), so I don't think they're going to ruin our lives by putting one of those in :unsure:

I want this paper to be maths based! Means less marks on stupid questions such as 'Why do scientists use standard procedure' or 'Explain what a standard solution is' - too much information to remember!

Reply 2323

Pandorax

11

I really hope it's not maths based because I can't do any of the maths DX Does anyone know what the grade boundaries were for the sample paper thing? It was really hard ;w; Like what were the grade boundaries for a C?

Reply 2324

username1344042

6

Original post by Sulfur

I want this paper to be maths based! Means less marks on stupid questions such as 'Why do scientists use standard procedure' or 'Explain what a standard solution is' - too much information to remember!

I like learning and applying science though! I don't want more maths - I've finished with that and I'm glad of it xD

Reply 2325

OP

Chromatography questions:

When the substance stops moving through mobile phase and is in the stationary phase, has it reached dynamic equilibrium?
When chemicals begin to go through the mobile phase, and separate (i.e three dots on the same line) what does this mean? - that it contained three different chemicals?
If chemicals on different lines stop next to each other, does that mean that they're the same chemical, and, if this happens but one of the chemicals keeps on moving further up, does it mean that it contains the same chemical and other chemicals?

Reply 2326

Student.178

9

Does any one have C7 past paper links? :smile:

Reply 2327

Pandorax

11

What is dynamic equilibrium? :s

Reply 2328

peacefully_

2

Can anyone some up Carboxylic acids and Alcohols please? I'm having trouble remembering them

Reply 2329

Original post by Pandorax

What is dynamic equilibrium? :s

Where the rate of the forwards and backwards reaction is the same and the reaction continues, there's just no change because the reactants and products are reacting and forming at the same rate. :smile:

Reply 2330

username1344042

6

Original post by peacefully_

Can anyone some up Carboxylic acids and Alcohols please? I'm having trouble remembering them

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

Reply 2331

Titration calculations,whatttt :frown:

I just can't understand them

Reply 2332

azo

8

Original post by Sulfur

Chromatography questions:

When the substance stops moving through mobile phase and is in the stationary phase, has it reached dynamic equilibrium?
When chemicals begin to go through the mobile phase, and separate (i.e three dots on the same line) what does this mean? - that it contained three different chemicals?
If chemicals on different lines stop next to each other, does that mean that they're the same chemical, and, if this happens but one of the chemicals keeps on moving further up, does it mean that it contains the same chemical and other chemicals?

No, dynamic equilibrium is when equal amounts of the substance being tested are leaving the mobile phase for the stationary phase, and leaving the stationary phase for the mobile phase.
Yes, it contains 3 different chemicals. They travel different distances because they spend different lengths of time in the mobile phase as some are more/less soluble in the solvent.
If chemicals stop on the same line it means they COULD be the same, but doesn't prove that they are the same. I don't really understand your last question :frown:

Hope I helped :smile:

Reply 2333

OP

Original post by azo

No, dynamic equilibrium is when equal amounts of the substance being tested are leaving the mobile phase for the stationary phase, and leaving the stationary phase for the mobile phase.
Yes, it contains 3 different chemicals. They travel different distances because they spend different lengths of time in the mobile phase as some are more/less soluble in the solvent.
If chemicals stop on the same line it means they COULD be the same, but doesn't prove that they are the same. I don't really understand your last question :frown:

Hope I helped :smile:

Thank you very much you have helped!

My last question was basically: if you place two chemicals on the baseline, and they're in the mobile phase and moving separately (like a race between two snails) and then finally they stop moving. You see that there's two matching dots, side by side, and that one of the chemicals has still continued going - does that mean that the second chemical contains the first substance AND another substance?

Reply 2334

azo

8

Original post by Sulfur

Thank you very much you have helped!

My last question was basically: if you place two chemicals on the baseline, and they're in the mobile phase and moving separately (like a race between two snails) and then finally they stop moving. You see that there's two matching dots, side by side, and that one of the chemicals has still continued going - does that mean that the second chemical contains the first substance AND another substance?

Hmmm I'm not 100% sure, but I know that if it travels the same distance it doesn't prove it's the same substance. So I think that shows that the second chemical contains another substance (as it has travelled further) and a chemical that COULD be the first substance but doesn't prove that it is.

Reply 2335

OP

Original post by azo

Hmmm I'm not 100% sure, but I know that if it travels the same distance it doesn't prove it's the same substance. So I think that shows that the second chemical contains another substance (as it has travelled further) and a chemical that COULD be the first substance but doesn't prove that it is.

Thank you very much! I'm now hoping for questions on chromatography tomorrow :biggrin:

Reply 2336

Anyone got any mnemonics for remmebering how to make an ester, a standard solution and all the long winded things like that?

Reply 2337

superdarklord

12

Original post by katiemckkk

Anyone got any mnemonics for remmebering how to make an ester, a standard solution and all the long winded things like that?

It's a terrible one :tongue:

For making an ester, Really Didn't Predict Dis.
Reflux, distillation, purification, drying.

The more stupid they are, the more likely I'll remember them :colondollar:

Posted from TSR Mobile

Reply 2338