How many significant figures do we give for values in chemistry?????

[raamish]

hey guys! help me out im really confused how many significant figures to give in the values.Sometime 2 sig fig are given and sometime 3 or 4 significant figures. Please somebdy help me

 

[Soulgamer]

It totally depends on the question. Care to give an example?

 

[raamish]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_23.pdf

In question no.2 how many significant figures shoud be given for the moles? SHould the same no. of significant figures be given for the whole question?

 

[Soulgamer]

Dude its simple, in this question give the moles to 1 significant figure.

a(i) 12/ 44 x 1.32= 0.36g
0.36/12= 0.03 moles
(ii) 0.06/1= 0.06 g
=0.06 moles
There you go I even solved the moles part for you

 

[oldfashionedgirl]

read the question very carefully in this regard and take note if all the values given in question paper are according to some particular sig. figure or not. If yes, then u have to give answers according to THAT particular number of sig. figures.
If not, then u can give ur answer correct to 2 or 3 sig. figure, but i'd suggest to keep it to 2.

 

[raamish]

ok man!

read the question very carefully in this regard and take note if all the values given in question paper are according to some particular sig. figure or not. If yes, then u have to give answers according to THAT particular number of sig. figures.
If not, then u can give ur answer correct to 2 or 3 sig. figure, but i'd suggest to keep it to 2.

okay man now can u tell me how to draw 3d structures of hydrocarbons ?

 

[oldfashionedgirl]

ok man!
okay man now can u tell me how to draw 3d structures of hydrocarbons ?

by 3d do u mean optical isomers?

 

[raamish]

hmmm ill give u a question: http://www.xtremepapers.com/papers/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w11_qp_23.pdf

Now in question 2bii) how will we draw the 3d structure?

 

[raamish]

Any method of knowing which bond will go out of the surface and which bond will go into the surface?