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

azo
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#2341
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#2341
(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

Hope I helped
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Sulfur
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#2342
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#2342
(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

Hope I helped
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?
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azo
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#2343
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(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.
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Sulfur
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#2344
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(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
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katiemckkk
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#2345
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Anyone got any mnemonics for remmebering how to make an ester, a standard solution and all the long winded things like that?
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superdarklord
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#2346
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(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
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

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katiemckkk
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#2347
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#2347
(Original post by superdarklord)
It's a terrible one
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

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Hahah thanks!! I always remember them better when they're stupid ones, for making a chemical I have Pass Sally Some Massive Headphones
Preparing feedstocks
Synthesis
Separating products
Measuring purity
Handling waste and by products
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azo
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#2348
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#2348
We don't need to know formulas of esters do we ?
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Amyjonesx
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#2349
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#2349
How do we "evaluate sustainability"? Do we just talk about RAWSHEEP ?
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Krollo
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#2350
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#2350
I've got a few mnemonics knocking around if anyone wants some:

Producing stuff sucks mighty hard - Preparation, Synthesis, Separation, Monitoring, Handling
SHARPWEE (sustainability)
Monkeys eat peeled bananas - Methane, Ethane, Propane, Butane
Rape dat purple dinosaur - Reflux, Distillation, Purification, Drying



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Sulfur
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#2351
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#2351
How would you see dynamic equilibrium in chromatography?
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Sulfur
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#2352
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#2352
(Original post by Krollo)
I've got a few mnemonics knocking around if anyone wants some:

Producing stuff sucks mighty hard - Preparation, Synthesis, Separation, Monitoring, Handling
SHARPWEE (sustainability)
Monkeys eat peeled bananas - Methane, Ethane, Propane, Butane
Rape dat purple dinosaur - Reflux, Distillation, Purification, Drying



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Do you have one for quantitative analysis of titrations?
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-sophia-
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What does this from the specification mean???

16. understand the main stages of a quantitative analysis:


 a. measuring out accurately a specific mass or volume of the sample
 b. working with replicate samples
 c. dissolving the samples quantitatively
 d. measuring a property of the solution quantitatively
 e. calculating a value from the measurements (IaS1.4)
 f. estimating the degree of uncertainty in the results (IaS1.5–1.6)
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Amyjonesx
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#2354
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(Original post by -sophia-)
What does this from the specification mean???

16. understand the main stages of a quantitative analysis:


a. measuring out accurately a specific mass or volume of the sample
b. working with replicate samples
c. dissolving the samples quantitatively
d. measuring a property of the solution quantitatively
e. calculating a value from the measurements (IaS1.4)
f. estimating the degree of uncertainty in the results (IaS1.5–1.6)
I dont understand that either my revision guide is so different to this
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-sophia-
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#2355
(Original post by Amyjonesx)
I dont understand that either my revision guide is so different to this
Mines got a really complicated flow chart :confused:
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JazzyT17
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#2356
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#2356
What is carboxylic acids general formula?
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JazzyT17
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#2357
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#2357
Does anyone have c7 past papers that they could give me the link of? thanks in advance.
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Krollo
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#2358
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#2358
(Original post by Sulfur)
Do you have one for quantitative analysis of titrations?
No, to be honest I tend to eschew the formulae and just think of the ratios involved.

Essentially the ratio of actual mass to relative formula mass is always constant in a reaction. If you remember that, you can work out everything you need on the fly.

(Though the spec says you'll get the formula anyway, if I've interpreted it correctly.)


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Sulfur
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#2359
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#2359
(Original post by JazzyT17)
What is carboxylic acids general formula?
Alkanes - no functional group
Alcohols - OH
Carboxylic acids - COOH
Esters - COO
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Amyjonesx
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#2360
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#2360
(Original post by JazzyT17)
What is carboxylic acids general formula?
If you mean like CnH2n+2 there isnt one for carboxylic acids what i normally do is draw it out and count how many C's and H's
remember they should end in COOH though


what are the states of carboxylic acids at room temperature?
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