Competition - post a photo you've taken of nature >>

OCR Gateway Chemistry C4C5C6 - 13/06/13

Scroll to see replies

Original post by benwalters1996

ImageUploadedByStudent Room1371061128.587693.jpg

Better orientation

Posted from TSR Mobile

thanks dude, helpful! btw this guy's really good too, i think it's been pointed out already: http://www.youtube.com/watch?v=NTzFN98uWt4

Reply 381

ryanb97

Original post by AR-13

It was 104 for the exam, not sure about c/w, jus say i scraped an a?

your 102 - was a very high B
Scraped an A means 80 ums

102 + 80 = 182

For a B you need 280
so in this exam you need 280 - 182 = 98 .... this is only a C

For a A you need 320
so in the exam you need 320 - 182 = 138 ....this is only a A ..an average one

i would really push for the A mate

Ryan

Reply 382

Mutleybm1996

Original post by ryanb97

If i got 40/48 in ca and 116/140 what would i need for an A? Raw mark wise?

Posted from TSR Mobile

Reply 383

tazza ma razza

thanks; but last year, people could sit c1,c2,c3 in january for the new spec. so just wondering if they did it this year.

also; what ums will A* begin at and at what mark will that be? my guess is 52 being A*

cheers

tazzzzzzza

Reply 384

ryanb97

Original post by L'Evil Fish

I'm worried now :lol:

Hopefully full marks in C4/5... Then C6 :mmm:

what if I forget things after my C4 exam?

As long as you make an entrance like this you will be fine :

Spoiler

Reply 385

AR-13

Original post by ryanb97

Thanks mate, i wud lov to get the a but i dnt thnk i no enough fr it, thnks btw

Posted from TSR Mobile

Reply 386

AR-13

Original post by AR-13

Thanks mate, i wud lov to get the a but i dnt thnk i no enough fr it, thnks btw

Posted from TSR Mobile

One last thing, wat wud the raw mark be for 98 ums

Posted from TSR Mobile

Reply 387

L'Evil Fish

Original post by ryanb97

As long as you make an entrance like this you will be fine :

Spoiler

Do you have a question on neutralization? I want to practise one...

Reply 388

BP_Tranquility

In biology, we're taught that fermentation does not occur in the presence of oxygen as normal respiration occurs, releasing CO2 and H2O.

In chemistry, we're taught that the presence of oxygen produces ethanoic acid. How do you reconcile these two ideas? :smile:

Posted from TSR Mobile

Reply 389

Knowing

Original post by BP_Tranquility

Posted from TSR Mobile

Where does it say that for chemistry?

Reply 390

Red Fox

Starting to worry about C6 but should secure at least 40 marks on C4 and C5.

Reply 391

BP_Tranquility

Original post by Knowing

Where does it say that for chemistry?

It says in my revision guide but also in the specification :smile:

ImageUploadedByStudent Room1371066972.000296.jpg

Posted from TSR Mobile

Reply 392

Mutleybm1996

Original post by Knowing

Where does it say that for chemistry?

the ethanoic acid comes from the presence of oxygen. otherwise ethanol is produced when there is no oxygen.

i'm sure that's the case...can't find it in the revision guide though!

Reply 393

Knowing

Original post by BP_Tranquility

It says in my revision guide but also in the specification :smile:

Posted from TSR Mobile

Oh I get it. Fermentation results in ethanol, not ethanoic acid.

Reply 394

ChloBrown98

I literally feel so unprepared for this exam tomorrow, can someone please tell me how to work out the molar mass and the mass of each element (c5) thanks!

Reply 395

Knowing

Original post by ChloBrown98

I literally feel so unprepared for this exam tomorrow, can someone please tell me how to work out the molar mass and the mass of each element (c5) thanks!

For the relative atomic mass of each element, look at the top number of their box in the periodic table.

To work out the molar mass, you work out the relative formula mass (basically add up all the relative atomic masses of all the elements in the formula/compound). This number is your molar mass (unit: grams/mole).

e.g. Molar mass of water.

Water = H2O
Atomic mass: H = 1, O = 16
Relative formula mass: (1 x 2) + 16 = 18

So the Molar mass of H2O is 18g/mol.

Hopefully this explains it :smile:

Reply 396

ChloBrown98

Original post by Knowing

Thank you! And it does explain it :smile:

I actually get it now, thanks!!! :biggrin:

Reply 397

Daniel97g

Can anyone explain how an ion-exchange resin works?

Reply 398

ChloBrown98

Original post by Daniel97g

Can anyone explain how an ion-exchange resin works?

Ions can be formed when electorns are lost or gained if this helps :smile:

and I have no clue about what the 'resin' part is. Sorry :frown:

Reply 399

Knowing

Original post by ChloBrown98

Thank you! And it does explain it :smile:

I actually get it now, thanks!!! :biggrin:

You're welcome ^^

Original post by Daniel97g

Can anyone explain how an ion-exchange resin works?

Basically you have an "ion-exchange column", which is packed with small beads. When you flush sodium chloride solution through it (salt water basically), the sodium ions get attached to the ion-exchange resin/beads. When hard water (water with calcium and magnesium ions in) passes through the ion-exchange column, the calcium/magnesium ions in the water are swapped with the sodium ions in the column, because calcium is more attractive. Therefore, the sodium ions replace the calcium/magnesium ions in the hard water, softening it.

(If all the sodium ions have been replaced, you just flush the column with NaCl solution again, clearing away the Ca/Mg ions, and regenerating it with new sodium ions)