As Chemistry ocr planning exercise Watch

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Craghyrax
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#161
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#161
Man! That was such a relief! It was so much easier than it could have been. I was very very very lucky!
Our lecturer gave us a mock almost identical to the practical and I practised the maths just before going in..so it was great!
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police
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#162
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#162
very lucky indeed craghyrax.....

what did u write for your three errors?
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Craghyrax
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#163
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#163
I wrote four or five I think. I wrote about obviously the issue of heat being lost, and the inadequacy of the apparatus in buffering the temperature..also affect of outside temp could affect internal (not likely but said it anyway) I wrote that after you emptied the anhydrous solids into the beaker, because you leave the lid off cause you're in a hurry to check temp, the anhydrous residue remaining in the empty container absorbs water from humidity of atmosphere which affects weight of the container when you reweigh it, which gives you innaccurate figure for mass. I wrote that the thermometer was really difficult to accurately read exact temp. I suggested digital thermometer and data logger. I suggested that using the same beaker and same thermometer for each for test could have resulted in contamination, and even with rinsing out with distilled water , remaining droplets in beaker could have slightly affected the molarity of acid inside by slightly diluting it (hey.. one mole can make a difference..lol). I can't remember what else if anything.
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tozhan
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#164
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(Original post by suzukiescudo)
werent u suppose to subtract it anyway?

a - (-b)= +answer
yeh, minus a negative number is positive...you add.

i subtracted... i got 16kjmol-1 ish, should have benn 60-70kjmol-1 ish
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mubarak
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#165
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#165
Well its not over yet, how far how fast and chains and rings can make or break the grades!
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alisajoosab91
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#166
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#166
hi i need help with a planning execise. can any1 help me please?

To determine the % purity of magnesium ribbon

Strips of magnesium ribbon become corroded on their surface is they are left lying around in the laboratory for several days. The corrosion layer is mainly a mixture of magnesium oxide and magnesium hydroxide, but a small amount of magnesium carbonate is sometimes present

plan experiment:
(a) to find out whether or not the corrosion contains any magnesium carbonate
(b) to determine the % purity by mass of magnesium in a corroded sample of magnesium ribbon using an acid of your choice

(16 marks)
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Pav90
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#167
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#167
Hang on, my plan is something about showing that sulfuric acid is dibasic and I'm doing OCR... Anyone else have this? PM me if possible.
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inteligant
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#168
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#168
yh im doin the ocr prove sulphuric acid is dibasic too
does any one know the mthod for gas collection?
cant find it anywhere on the net:confused:
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xavierx
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#169
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#169
one method is titration one gas collection that's what is says on the sheet other than that i have no idea.
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ryana12
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#170
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#170
hey i really need help...ive just been told that my chemistry coursework has to be in on monday....i was away but my teacher has told me if i dont get it in then forget it...all my class mates havent had any help either he jus gave us the sheet and told us them they had a week to do it.....would people be able to help me please add me on msn [email protected]

please thnx
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Craghyrax
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#171
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Just to clear up confusion: I can't help people with Chemistry because it was two years ago I did it, and I've forgotten everything. I'm now doing a degree in Social Sciences :p: Sorry to be a wet blanket. I'm only posting because a few people have PMd me in the last few days
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quintsy
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#172
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#172
To avoid confusion considering the age of this thread, could we maybe start a new one to discuss your coursework please? Others who can help you will be more likely to notice it that way.
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