All Leaving Cert Chemistry posts
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    Paper discussion ddp.cronin

    I personally thought that was the hardest Chem so far. Usually titration is simple and straight forward. Found this one hard. Anyone get 4.8% for w/v

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      yes whooooo got 4.8

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      I got that too! I thought the paper was so hard, I was hoping for an A, got a B2 in the DEB, I'll be lucky to get that after that paper

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      What did you get for instanteneous rate at 4min

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      I got something like 7. .... I don't clearly remember but it was in the sevens

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      What did you get for the Kc?

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      Guys I got 48%. I reanalysed the paper and I don't think I'm wrong because they mentioned ORIIGINAL vinegar as opposed to DILUTED vinegar!!

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      pretty sure you'd be dead with 48% v/w in vinegar :) , but maybe you are right time will tell

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      I think 8.something for the instantaneous rate. I think they asked for the diluted vinegar no?

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      no its original

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      Googled it ... "optimum amount of acetic acid in vinegar is between 4 and 5 percent by weight." 4.8% sounds right

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      its 4.8%. Its 48% in the orginal but thats per L. You have to write it per 100cm

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      w/v is per litre and i got 4.8% were we suppose to know the makeup of arsine?

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      it gave it in the question. As with 3 hydrogen atoms

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      ahh fuck i couldent find it in the peroidic table too late now

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      What did people get for the KC value in question 7?

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      For Kc I got 12.25 but think it's wrong.. I got loads of different answers and wasn't sure which to put down, went with this in the end

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      Which titrations are used to standardise sodium hydroxide?

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      I said anhydrous sodium carbonate to standardise HCl and then HCL to standardise sodium hydroxide ?

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      Ah yeah thanks that sounds right

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      I got something like 3920 for the Kc definitely wrong lol

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      I got 196000

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      for the KC

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      KC was 196000

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      I got like 7.5 or something in the instantaneous rate.

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      I got around 7.5 in the instantaneous rate.

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      Agh I originally got that for Kc but thought it was wrong as there was a two at the start of the equation

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      Different values of Kc probably came from whether moles were divided by the 50Litre volume of the container, which I believe was to be divided before subbing into the Kc expression.

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      There was a misprint on the ordinary paper, HCL titration had the wrong chemical equation I think?

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      the kc i got had 4 numbers, but i converted the grams to moles, found the moles at equilibrium and divided by 50 then I used the formula to find the kc

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      If 4.8% is the answer then I messed up in a place where I wrote 0.8 instead of 0.08. This meant my other answers further down were also affected by this. How many marks will I lose for this? Will I only be marked down for the initial slip or will marks be taken away from the other answers as well?

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      I am hoping that they will account for slips. They would hardly be that cruel

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      to take off marks for the remainder for the question

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      Having done LC would you advise getting grinds if one only gets 74% in their summer house exam

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      I am a firm believer, when it comes to subjects like chemistry and biology, that one will only waste money on grinds. Let alone the fact that I had great teachers in these subjects, I feel that the textbooks are so comprehensive and easy to follow. Working hard on each chapter and understanding the material is vital and this is made easy by the great layout of information in the textbooks.

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      I got 4.8% for the concentration too, and 196,000 for Kc. My instantaneous rate was somewhere around 8 or 9 but they generally accept a range of values for that!

      Regarding grinds, I agree with Insa333 - I don't think any grinds teacher could explain the material better than the textbooks do! It takes time and work but it all clicks eventually

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