**Chemistry...Before/After

Hayezer · 19-06-2012 9:00pm

I said adding too much of the acid would make water acidic, corroding water pipes. I said too much chlorine would make water undrinkable? Bit of a guess.

ChemHickey · 19-06-2012 9:08pm

Yellowstars wrote: »

what did ye say for Q7 problems arising after adding too much of fluorin or chlorine(there the ones i chose). oh and q8 9(e) the reagent and catalyst to bring about conversion R. and the instantaneous rate at 60 seconds? aaaand 4e.the oxidation/reduction balance?

I didn't do q7 but too much chlorine would be untasteful. I would have picked the acid/base saying too much acid and it would damage teeth, too much base would damage piping.

hydrogen with nickel catalyst

I got like 27? I think I'm wrong!

I can't remember the ox,red question.

BL1993 · 19-06-2012 9:09pm

Hayezer wrote: »

I said adding too much of the acid would make water acidic, corroding water pipes. I said too much chlorine would make water undrinkable? Bit of a guess.

Same. I also mentioned that too much chlorine irritates eyes if you wash your face with the water. :P

Yellowstars · 19-06-2012 9:09pm

thanks!

wb 4b. balanced nuclear reaction?

..also for 7c..would u get away with saying heavy metals kill fish?

ShaunaMoll · 19-06-2012 9:14pm

Yellowstars wrote: »

what did ye say for Q7 problems arising after adding too much of fluorin or chlorine(there the ones i chose). oh and q8 9(e) the reagent and catalyst to bring about conversion R. and the instantaneous rate at 60 seconds? aaaand 4e.the oxidation/reduction balance?

For the problems arising after adding too much fluorine, you could say that it gives the water a bad taste, and too much chlorine irritates skin membrane.

I'm guessing you meant Q8 (d) - reagent was h2 and catalyst was Ni?

Didn't do the rate of reaction question!

ChemHickey · 19-06-2012 9:16pm

Btw, it's too much FLUORIDE not fluorine... lets hope you didn't say fluorine.

ei.sderob · 19-06-2012 9:16pm

I got a pretty small answer for the instantaneous rate as I put time on the x axis. Think it's right though, I mean I can't think of anything I did wrong for it...:/

Hayezer · 19-06-2012 9:18pm

ei.sderob wrote: »

I got a pretty small answer for the instantaneous rate as I put time on the x axis. Think it's right though, I mean I can't think of anything I did wrong for it...:/

I got 0.00 something i think :pac:

ChemHickey · 19-06-2012 9:19pm

Time was supposed to go on the y axis wasn't it?

ei.sderob · 19-06-2012 9:20pm

Hayezer wrote: »

I got 0.00 something i think :pac:

I think that's right like. I mean it can't be too large a number as it's grams per second like! Pretty hopeful for the A1. What did ye say for the pipette filler? That was odd.

ShaunaMoll · 19-06-2012 9:21pm

ChemHickey wrote: »

Btw, it's too much FLUORIDE not fluorine... lets hope you didn't say fluorine.

Hahaha, yeah I said NaF - my brain is pretty much fried right now, typing skills aren't the best!

ei.sderob · 19-06-2012 9:21pm

ChemHickey wrote: »

Time was supposed to go on the y axis wasn't it?

Really? I mean if you're in control of time then shouldn't it be on the x? I'm probably wrong though!

abbeymate · 19-06-2012 9:27pm

Well everyone, I got the 8 test tubes the for ethene experiment but feel terrible after remembering that I didnt multiply by two for the titration calculations :-S Such a stupid mistake! :-/ Anyway, before I take a few heavy swigs of concentrated alcohol from my conical flask in depression, how much marks will I lose? As in in my answer for grams per litre completely wrong seeing as I got the first part wrong?

FaoiSin · 19-06-2012 9:28pm

ei.sderob wrote: »

Really? I mean if you're in control of time then shouldn't it be on the x? I'm probably wrong though!

Nah you're right as far as I know. I didn't like that question that much as I wasn't sure if my calculations were accurate so I did organic.

Did anyone else find the organic really nice?

finality · 19-06-2012 9:29pm

ChemHickey wrote: »

Time was supposed to go on the y axis wasn't it?

I think time was the x axis. Because the rate is loss of grams/time

and if time is on the x axis then that equals the slope of the graph. If time's on the y axis you'd have to invert the slope to get the instantaneous rate.

ChemHickey · 19-06-2012 9:31pm

finality wrote: »

I think time was the x axis. Because the rate is loss of grams/time

and if time is on the x axis then that equals the slope of the graph. If time's on the y axis you'd have to invert the slope to get the instantaneous rate.

Ah sure, I won't be counting that question anyway! :L I made stupid mistakes in all of that question!

I did 10questions and all three parts in 10 and 11 so I should be covered for the A1... touch-wood.

And I was only going by the way the graph I thought would look.. and I hate rates anyway! :L

ei.sderob · 19-06-2012 9:31pm

abbeymate wrote: »

Well everyone, I got the 8 test tubes the for ethene experiment but feel terrible after remembering that I didnt multiply by two for the titration calculations :-S Such a stupid mistake! :-/ Anyway, before I take a few heavy swigs of concentrated alcohol from my conical flask in depression, how much marks will I lose? As in in my answer for grams per litre completely wrong seeing as I got the first part wrong?

What part are you talking about multiplying by two for? You had to divide by two for the finding the mass of Na2Co3 and then the HCL titration was as normal. I could be completely misinterpreting your question though!

ChemHickey · 19-06-2012 9:33pm

ei.sderob wrote: »

What part are you talking about multiplying by two for? You had to divide by two for the finding the mass of Na2Co3 and then the HCL titration was as normal. I could be completely misinterpreting your question though!

I think he/she means that they didn't put HCL over two, then multiplying across by two then when you need to get the M on it's own. I think

finality · 19-06-2012 9:33pm

abbeymate wrote: »

Well everyone, I got the 8 test tubes the for ethene experiment but feel terrible after remembering that I didnt multiply by two for the titration calculations :-S Such a stupid mistake! :-/ Anyway, before I take a few heavy swigs of concentrated alcohol from my conical flask in depression, how much marks will I lose? As in in my answer for grams per litre completely wrong seeing as I got the first part wrong?

I don't think you're supposed to multiply by 2. Is this question 1? You're told it's a 0.05 molar solution - that's 0.05 moles per litre. It doesn't matter that you've only made 500cm^3 of it as it's still a 0.05 molar solution.

Even if you got the moles per litre wrong, you'd still get the marks for the grams per litre provided your work for that part of the question was correct.

ei.sderob · 19-06-2012 9:33pm

ChemHickey wrote: »

Ah sure, I won't be counting that question anyway! :L I made stupid mistakes in all of that question!

I did 10questions and all three parts in 10 and 11 so I should be covered for the A1... touch-wood.

And I was only going by the way the graph I thought would look.. and I hate rates anyway! :L

I can NEVER find the time to do extra questions in Chem exams! Are you doing something with Chemistry in college? Just going by your name like...

ei.sderob · 19-06-2012 9:35pm

finality wrote: »

I don't think you're supposed to multiply by 2. Is this question 1? You're told it's a 0.05 molar solution - that's 0.05 moles per litre. It doesn't matter that you've only made 500cm^3 of it as it's still a 0.05 molar solution.

Even if you got the moles per litre wrong, you'd still get the marks for the grams per litre provided your work for that part of the question was correct.

Do you divide the .05 by 2 when finding the mass of Na2CO3 or what's the deal with that??

FaoiSin · 19-06-2012 9:35pm

Yeah I made a mistake by getting it in 500cm^3 instead of one litre. Hopefully won't lose that many marks. Confident I got the rest of the paper right anyway. Can't believe I didn't spot it.

ChemHickey · 19-06-2012 9:35pm

ei.sderob wrote: »

I can NEVER find the time to do extra questions in Chem exams! Are you doing something with Chemistry in college? Just going by your name like...

I'll be doing Math Science in Galway which involves chemistry in the first two years so ya, kinda... Kinda tempted to do a postgrad in chem though... just love it. I had time to do the water question too! But I decided against it as I said I'd reread the paper instead! Good thing I did as I saw the titration figures had to be to 2 decimal places... Phewwww.

ShaunaMoll · 19-06-2012 9:36pm

Anyone know what the other pair of structural isomers were in the reaction scheme in Q8?

Think I said Propanal and Propanone but it was a total guess!

Hayezer · 19-06-2012 9:37pm

Organic was great, think I may have gotten 50/50 if I remember correctly. Did 10 questions, hopefully I'll get a B3 or B2?

ChemHickey · 19-06-2012 9:37pm

ei.sderob wrote: »

Do you divide the .05 by 2 when finding the mass of Na2CO3 or what's the deal with that??

I think the OP of that question forgot to put n=2 for HCL, he/she had it at n=1 and then when cross multiplying, there was no x2 on the RHS

finality · 19-06-2012 9:37pm

ei.sderob wrote: »

Do you divide the .05 by 2 when finding the mass of Na2CO3 or what's the deal with that??

Yeah. You do, I THINK I did in the exam...hopefully :L

ChemHickey · 19-06-2012 9:38pm

ShaunaMoll wrote: »

Anyone know what the other pair of structural isomers were in the reaction scheme in Q8?

Think I said Propanal and Propanone but it was a total guess!

CORRECT!

ei.sderob · 19-06-2012 9:38pm

I'm not sure if I saw the "to two decimal places"....I hope I have. This will eat away at me now!!!:P

ShaunaMoll · 19-06-2012 9:39pm

ChemHickey wrote: »

CORRECT!

Oh THANK GOD. Love organic and it nearly killed me thinking that I got that part wrong!

**Chemistry...Before/After

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