# ocr chemistry evaluation task 3 - evaluating carboxyllic acids - (help)

titrations
measuring % error
carboxyllic acids

any other relevant answers related with the evaluative test out of 20 marks

thanks

Posted Tue 24th April, 2012 @ 15:07 by M.Ahmed

Percentage error is:

Percentage Error = Maximum Error / Measured Value X 100

For example.
Maximum Error for the following apparatus are:
Balance = +/- 0.01
Pippette = +/- 0.1

And the Measured value for each are:
Balance = 0.15
Pippette = 25

Then...the percentage error is:
Balance percentage error = 0.01 / 0.15 X 100 = 66.66%
Pippette percentage error = 0.1 / 25 X 100 = 0.3%

You can now also work out your maximum total error.
Maximum total Percentage error = Balance Percentage error + Pippette Percentage error
Maximum total percentage error = 66.66 + 0.4 = 67.06%

Answered Tue 24th April, 2012 @ 16:46 by Oliver

Apparently there are something to do with isomers in the paper, can someone add more info? This is my last shot at it.

Answered Fri 27th April, 2012 @ 19:01 by AJSarah

Hi, I haven't done it yet but apparently you need to know about E/Z isomers, calculations using mole, percentage error, Equation between Metal hydroxide and carboxylic acid, reactions of alkenes with bromine water and infrared spectroscopy.

Has anyone done the A2 Evaluative on Benzoic Acid?

Answered Sun 13th May, 2012 @ 20:58 by Pri 0103

Is this what we need to know? Thanks so much :D

The carboxylic acids are jsut like hydrocarbons, but have a C=O and C-O-H coming from the end carbon (carbon is the same).

Not sure about the other 2 :/

Answered Tue 24th April, 2012 @ 15:33 by Oliver

How do you work out titrations though and why do you do a titration ......?.?.

Answered Tue 24th April, 2012 @ 16:59 by M.Ahmed

When you worked out the % error for the balance ,,,, would it not be 6.66% .?
And then when you would work out the total %error would it not be ..... 6.666+0.4=7.066% ?????

Thanks

Answered Tue 24th April, 2012 @ 17:29 by M.Ahmed
Edited by M.Ahmed on Tue 24th April, 2012 @ 17:34

@Oliver thanks sooo much :)

Answered Wed 25th April, 2012 @ 13:29 by Amyy

M.Ahmed, How did you know that titrations would be in the evaluative? We jsut got told that it had carboxylic acids, and it was an evaluative.

Answered Wed 25th April, 2012 @ 16:09 by Oliver

Not saying. You deserve to do badly.

Answered Thu 26th April, 2012 @ 16:30 by Oliver

hi there guys i need sum info on the task 3 (Evaluative Taks)

thanks

Answered Thu 26th April, 2012 @ 19:11 by Doctor

thanks man you are awesome

Answered Fri 27th April, 2012 @ 16:04 by Doctor

can you please be a little more specific as this is  a 15 marker it's pretty important i need a really good grade in it man

thanks

Answered Fri 27th April, 2012 @ 16:05 by Doctor

thank you mate

Answered Sun 29th April, 2012 @ 18:38 by Doctor

is there some sort of infra red spectroscopy that will be in the evaluative task

thanks ASAP

Answered Mon 30th April, 2012 @ 16:09 by Doctor

yes you need to identify a carboxylic acid on an ir spectrum

Answered Thu 3rd May, 2012 @ 11:07 by anna

Hi so pls pls pls pls pretty pls with sugar on top can anyway give me a bit more detail about what going to be on the paper,

It's tommorrow and I have a french oral on the same day and then another evalutive task the very next day so it'd be a great help

Thanks

Answered Tue 8th May, 2012 @ 22:19 by Chika