AQA Chemistry Unit 2 (resit) CHEM2 10th June

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Does anyone know the answer to why acidifying bleach is dangerous question, I really didn't get it so i just put down that Nacl and Naclo are already acidic so acidifying further would give a strong acid which is dangerous as corrosive-but that seems way too simple to be correct. :/

The eq. is NaOH + Cl2 <-> ClO- + H+ + NaCL

If you add acid you incr. the conc. of H+ Ions which will cause the eq. to shift left, thus producing Cl2 which is toxic.

(edited 7 years ago)

Reply 301

Randomer98

You wouldn't be able to resit AS but you would be able to resit A2

Reply 302

Jackmilne95

Original post by RME11

The eq. is NaOH + Cl2 <-> ClO- + H+ + NaCL

If you add acid you incr. the conc. of H+ Ions which will cause the eq. to shift left, thus producing Cl2 which is toxic.

Isnt it 2NaOH + Cl2 -> NaClO + NaCl + H2O?

Reply 303

Hdhcuksbdjcuhs

Hi i also made a mistake on the fermentation one and spoke about advantages and disadvantages of hydration rather than fermentation. Did u find out if we lose or gain marks as we did imply the points.

Reply 304

Hopefulmedic15

Original post by Jackmilne95

Isnt it 2NaOH + Cl2 -> NaClO + NaCl + H2O?

Yes that's the correct equation.

I don't know what would be the correct answer to the question but I'm assuming they wanted us to say the H+ would react with the OH- ions on the LHS which would remove them, so equilibrium would shift to the left to oppose the decrease of OH- and would produce more toxic Cl2 gas.

I fluffed up and said it would react with the NaCl to form HCl but I don't think that's right.

Reply 305

Jackmilne95

Original post by Hopefulmedic15

Ok cool. I just said that acidifying the solution would cause the equilibrium to shift to the left to oppose the increase in H+ ions and so the conc/moles of chlorine gas would increase and chlorine gas is toxic in high concs

Reply 306

Jackmilne95

Original post by EmmaHarvard

Can someone put together mark scheme please?

Put together some rough answers on page 12 for quite a few questions. They should all be correct

Reply 307

tayyabs17

Hey does anyone know how many marks in total question 9 was?

(edited 7 years ago)

Reply 308

nooonooo

Original post by RME11

The eq. is NaOH + Cl2 <-> ClO- + H+ + NaCL

If you add acid you incr. the conc. of H+ Ions which will cause the eq. to shift left, thus producing Cl2 which is toxic.

ahhh, thank you, don't know why I didn't think to write out the equation

Reply 309

Superwoman212

Did you guys tick the box 'oxidising agent'?

Reply 310

soLit

Original post by girl :D

omd yes!!!!!!!!!!!!!!

Hate to break this ...

They ignore partial charges UNLESS they are incorrect. If they are wrong, they penalise you.

Reply 311

Hasib98

Original post by jessyoung

Guys I'm pretty sure there was a double bond in the alcohol. The molecular formula was C4H8O for A and B and C4H10O for P and Q

yeah there had to be one, it was a tertiary alcohol too right?

Reply 312

jbman690

Is the paper you guys did different from the one the yr 12s did? i cant remember any of these questions

Reply 313

House6797

hey guys im in A2, i didnt do the unit 2 test, but to summarise how did people find it?
were there a lot of curveballs, like were questions weirdly written

trying to prepare for my chem 4 paper on tuesday

Reply 314

Hopefulmedic15

Original post by jbman690

Is the paper you guys did different from the one the yr 12s did? i cant remember any of these questions

Yes it's a different paper to the new spec the year 12s did

Reply 315

Hasib98

Original post by lahigueraxxx

Okay it was definitely the alcohols that we had to identify (A and B). I finished early and went through the paper to double check everything and initially I had written the aldehyde and ketone but the question definitely wanted the alcohols! Thank god i double checked!

oh crap i wrote the corresponding aldehyde and ketone ffs

Reply 316

Bsg.01

That exam was really goood

Reply 317

Hasib98

Original post by Simple Harmonic

What did everybody draw for the hydration of prop-1-ene mechanism? I used sulfuric acid instead of water, everybody's answer in my class conflicted with mine but using sulfuric acid is actually the technically correct mechanism.

yes bro sulfuric acid, which would then go on to form the secondary alcohol. thank god i realised otherwise i would've left the mechanism that would form a primary alcohol

phew

Reply 318

Hasib98