# Tips for Chemistry Practicals (P3)

#### toxicdevil

how to calculate the percentage error? in my mock i Did 0.05 multiply by 2 (as two reading from burette) and divide by hundered mulitply by the Reading of burette but i got zero. marks.

#### Mustehssun Iqbal

ur welcome ... how r u guys preparing for practical ?
trying to use imagination and solving past papers xD

#### perkypearl

trying to use imagination and solving past papers xD
lol ok .. so u were doing that imagining a test tube in ur hand and taking its mass HAHAHAHA

#### Mustehssun Iqbal

lol ok .. so u were doing that imagining a test tube in ur hand and taking its mass HAHAHAHA
haha didn't reach the test tube part yet. I remember taking the mass in kind of a tiny bucket. Done this one in the lab. xD

#### Mustehssun Iqbal

Here's another question. How many significant figures are to be used in calculations and in table of data??

#### perkypearl

Here's another question. How many significant figures are to be used in calculations and in table of data??
wt i know is u r suppose to write the s.f according to question .. if in question there r two s.f thn we will write 2 s.f

#### Mustehssun Iqbal

wt i know is u r suppose to write the s.f according to question .. if in question there r two s.f thn we will write 2 s.f
got it . Thanks a lot

#### Mustehssun Iqbal

What apparatus to use to measure a solvent/ liquid of volume 20 cm^3??

#### toxicdevil

It an be a 10cm3 pipette used twice or a burette or a measuring cylinder

#### Mustehssun Iqbal

It an be a 10cm3 pipette used twice or a burette or a measuring cylinder
Ok thanks a bunch

#### Mustehssun Iqbal

Two more questions on Chemistry paper 3:
when we use a different method of molar calculation than the one given in the marking scheme, and our answers are correct, do we get the marks then??
Second question, this might sound silly but, do we have to learn the table of test for ions??

#### Tazyeen K

Two more questions on Chemistry paper 3:
when we use a different method of molar calculation than the one given in the marking scheme, and our answers are correct, do we get the marks then??
Second question, this might sound silly but, do we have to learn the table of test for ions??
You dont need to learn the table for the tests of ions. Its always given!

#### iKhaled

Two more questions on Chemistry paper 3:
when we use a different method of molar calculation than the one given in the marking scheme, and our answers are correct, do we get the marks then??
Second question, this might sound silly but, do we have to learn the table of test for ions??
memorizing them will help u to save time though, but it is always given its all up to u if u wanna memorize it or not and for the first question u asked i was gonna ask the same question and i also want to know how to draw a line of neutralization to determine the volume used blabla on the graph? do uk how?

#### sidbloom

i usually mess up my question paper and it get stained with various chemicals (thanks to the fact that out lab is always crowded and people are always borrowing stuff from u ) so will i get any sort of deduction for that
and also u said that we can ask for new chemical if we think that they are not right and then one more thing u said that do not take more the 45 min to do the salt analysis so should we do that question first and then head on with the second question

#### user

I remember one paper too where they asked to test for Aldehyde and Ketone, but I don't think it was a recent one.
it was a recent one..i think june 2011 or may be one in 2010

#### farhan143

can any 1 explain me what is a rough titration!!!!
given in 2011 may/june.

#### user

can any 1 explain me what is a rough titration!!!!
given in 2011 may/june.
aoa wr wb
it's like u just add the solution from the burette faster...and roughly get to know where's the end point... instead of adding drop by drop..
so if ur rough titre is around 23 for example..
then when u do it next, an accurate one..u can add 20 cm^3 directly..and then start to add drop by drop

#### farhan143

aoa wr wb
it's like u just add the solution from the burette faster...and roughly get to know where's the end point... instead of adding drop by drop..
so if ur rough titre is around 23 for example..
then when u do it next, an accurate one..u can add 20 cm^3 directly..and then start to add drop by drop

this question involved a lot of calculations....

this is from the year 2011 may/june.......

#### farhan143

Can any1 tell me the Hess's Law formuale, the enthalpy change formula !!!!!
because 2011 may/june second question involved a lot of it !!!!

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