Root-squared error

24.12±0.09 ml of 0.100±1x10-4 M HCl was required to neutralise 25.0±0.05 ml of NaOH.

Calculate the root-squared error in the concentration of NaOH in mol dm-3.

Whenever I calculate these I get the wrong answer, please could someone tell me how to do it and what answer you get?

Thanks

Reply 1

generalebriety

I've never heard of the root-squared error, and this sounds like it belongs in chemistry rather than maths. :smile:

I'll try and help you if you tell me what's going on though. :p:

Reply 2

dfghj

Oops forgot to say that concentration of the NaOH is 0.0965M.

Reply 3

dfghj

Oh I thought it was mathsy! I may give it a go in the Chem forum then.. :p:

Reply 4

generalebriety

It might well be. But I've never heard of it, Wikipedia's never heard of it... in fact, Google's barely heard of it. :p:

Sure you have the name right?

Reply 5

nota bene

wildelectricity

Oh I thought it was mathsy! I may give it a go in the Chem forum then.. :p:

Well, I guess some mathematicians have read chemistry though :tongue:

I would possibly be acle to answer if I knew what this root-square error was... is it something like adding terms and square them and then take the square root of it... :s-smilie:

Reply 6

dfghj

Yep it's called root-squared error, apparently. I've attached the notes we were given.

For this example question ...

24.12±0.14 ml of 0.100±1x10-4 M HCl was required to neutralise 25.0±0.05 ml of 0.0965M NaOH.

... the answer given was 0.0006

rtsqrderror.bmp282.9KB

Reply 7

generalebriety

Sorry, I really have no idea what that means. :p:

Reply 8

dfghj

Haha no problem ... I thought I did but I keep on getting the answers wrong and I have no idea why Oh well, thanks anyway!

Reply 9

nota bene

Well, I understand the method of calculating the thing, but I can't see which values are which in here... which are to be multiplied/divided... :s-smilie:

Reply 10

dfghj

I did it and got the answer right woo! Calculate like this...

0.0965 x sqrt [ (0.09/24.12)² + (1x10^-4/0.100)² + (0.05/25)² ]

Probably doesn't make much sense if you don't do chemistry, I guess.