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

OP

Original post by -sophia-

I put that sodium floats and melts in water but sinks in alcohol

Hmm aren't both answers correct? Can't remember the context of the question except a similar one came up in a past old spec paper we did in class.

Reply 2583

-sophia-

9

Original post by Sulfur

Hmm aren't both answers correct? Can't remember the context of the question except a similar one came up in a past old spec paper we did in class.

I think so! :smile:

Reply 2584

Original post by Sulfur

Similarity - both produce water H2O
Difference - hydrocarbons and oxygen produce CO2, hydrogen and oxygen doesn't

I thanks

put that too :smile:

i wasn't sure as not many in my school answered it, what did you put for the tittration 6 marker?

Reply 2585

romaiseb

8

What two boxes did everyone join in the ester question?

Reply 2586

-sophia-

9

Original post by romaiseb

What two boxes did everyone join in the ester question?

Left hand side I put the second one (i think)
Right hand side I put the last one

Reply 2587

Krollo

17

Original post by romaiseb

What two boxes did everyone join in the ester question?

It was the second and the fourth, I think.

Posted from TSR Mobile

Reply 2588

Original post by romaiseb

What two boxes did everyone join in the ester question?

2nd and last i think?the one with ethanol and the one with water

Reply 2589

iodqwm

Original post by lyricalvibe

2nd and last i think?the one with ethanol and the one with water

was it a 2 marker? and i thought it was one line?

(edited 9 years ago)

Reply 2590

Krollo

17

Original post by iodqwm

was it a 2 marker?

One mark for left and one for right, I would expect.

Posted from TSR Mobile

Reply 2591

OP

Original post by lyricalvibe

I thanks

put that too :smile:

i wasn't sure as not many in my school answered it, what did you put for the tittration 6 marker?

I thought it was quite odd to be honest, don't even know why...

Titration 6 marker:

Fill burette with 25.0 cm3 of the acid
Pipette alkali into conical flask accurately
Put white tile under conical flask to observe reaction (change in colour) see change much more vividly
Slowly, drop by drop, add the acid to the alkali through the burette after adding about two drops of indicator
Keep adding until there's a colour change (neutralisation)
Calculate the total amount of acid used by total volume of acid - acid from end point
First titration is a rough titration, repeat at least three times to get +- 0.2 cm3 from rough titration
Once you've done three titrations, calculate the mean as it's accurate and the best estimate of the true value and takes into account the uncertainty of the data

(edited 9 years ago)

Reply 2592

corporal

5

Original post by romaiseb

sodium hydroxide isn't a gas is it? I'm so stupid :frown:

+ for the fertilizer question I said that fertilizers are used positively for fertilizers to increase growth of plants and increase yield - they are not just used for harmful reasons

It is also useful as the world is growing and more food needs to be fed to people.

Reply 2593

corporal

5

Original post by lyricalvibe

2nd and last i think?the one with ethanol and the one with water

Yeah it was the 2nd box linked to the last box( beacuse each side of the reaction - 12 hydrogen atoms)

Reply 2594

DDan123

8

Thankfully it was a decent paper :biggrin:

So pleased, hopefully P7 goes well

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Reply 2595

OP

For the ammonia one I wrote:

Ammonia is used to help the world food corporation (meant to say production, still right?) so that people can have food - the benefits outweigh the risks of hurting people - it can be used as a fertiliser that doesn't hurt people, but can hurt animals

How many out of three would you say?

(edited 9 years ago)

Reply 2596

username1344042

6

Original post by Sulfur

For the ammonia one I wrote:

Ammonia is used to help the world food corporation (meant to say production, still right) so that people can have food - the benefits outweigh the risks of hurting people - it can be used as a fertiliser that doesn't hurt people, but can hurt animals

How many out of three would you say?

I'm not sure if you had to mention that it increased crop yield. Also, I'm not sure they'd mark the corporation part :s-smilie:

I'd say 2 maybe 3?

Reply 2597

OP

Original post by olmyster911

I'm not sure if you had to mention that it increased crop yield. Also, I'm not sure they'd mark the corporation part :s-smilie:

I'd say 2 maybe 3?

Thank you

Reply 2598

Original post by Sulfur

I thought it was quite odd to be honest, don't even know why...

Titration 6 marker:

Fill burette with 25.0 cm3 of the acid
Pipette alkali into conical flask accurately
Put white tile under conical flask to observe reaction (change in colour) see change much more vividly
Slowly, drop by drop, add the acid to the alkali through the burette after adding about two drops of indicator
Keep adding until there's a colour change (neutralisation)
Calculate the total amount of acid used by total volume of acid - acid from end point
First titration is a rough titration, repeat at least three times to get +- 0.2 cm3 from rough titration
Once you've done three titrations, calculate the mean as it's accurate and the best estimate of the true value and takes into account the uncertainty of the data

Yep, it felt too much like C6
I said the same steps , i remembered your explanation partly aswell :smile:

i also included about standard procedure and how that means accuracy and how it's scientific standard procedure-is this even right?- quickly and how everything is for accuracy, also said somethimg about ignoring oytliers for the mean but i didn'tgo intovas much detail as you with things like the white tile-i just couldn't remember it :frown:

What did you put to balance the equation?

Reply 2599