need a hand with some work

hi guys i havent been on for a while cos ive got loads of work at the mo. anyway im really stuck on a question i have to do for my chemistry assignment

this is it exactly:

3.575g of a hydrated metal carbonate (M2CO3.xH2O) require 25.0cm3 of 1.5M hydrochloric acid in a titration. calculate the relative molecular mass of the hydrated carbonate.

the numbers in the brackets are supposed to be subscript, but it wouldnt let me put them in on here.

anyway, can anyone help me with this cos i fully understand titrations and doing calculations on them, but from what i see there just isnt enough info here to answer the question. dont ask me if im being blonde and if there are some other details written above the question because their isnt. all i have is a list of questions like this.

i would appreciate any help anyone can give.

oh yeah and ill try and get on here more

Hi,

Firstly, calculate the number of moles of HCl that was needed to neutralise the metal Carbonate:

Number of moles = (Molarity * Volume) / 1000
Number of moles = (1.5M * 25cm^3) / 1000
Number of moles = 0.0375 moles

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So, 0.0375 moles of HCl were needed to neutralise the metal Carbonate.

HCl dissociates to H+ and Cl-
M2CO3 dissociates to 2M, C, and 3O.

Therefore, 0.0375 moles of HCl neutralised 2M (i.e. - 2 of the metal ions). How many moles neutralised 1? Divide 0.0375 by 2 to get 0.01875 - This is the number of moles of the metal Carbonate.

Therefore, we can now calculate the molecular mass of the metal Carbonate using the following formula:

mass = (number of moles * molecular mass)
molecular mass = mass / number of moles
molecular mass = 3.575g / 0.01875 moles
molecular mass = 190.667 atomic mass units

So, answer is 190.667!!

Kevin

yes all the best for your assignment.

thanks chucky.

hey guess what, it was the same as all the other questions i had, just written very differently. im a dumbass :L.

anyway yeah thanks for the help, sounds like you enjoyed working that out

I used to love doing these equations in Chemistry class but I'm a bit rusty. Was the way I did it correct?

Chucky wrote:I used to love doing these equations in Chemistry class but I'm a bit rusty. Was the way I did it correct?

wow i love this site. before i knew i had AS i just thought i was wierd, i enjoy doing them too. and yeah it was correct, or at least i hope so cos it was the same way i was doing all the others before i got stuck. i wont get it back for a while cos i handed the project in now so i cant be sure.

hehe, yippee! Yeh, I really love doing these chemical equations. I also love doing Maths in general. My favourite is solving a very complex algebraic equation with lots of variables. It's like writing poetry or something. In the second year of my course, I got 100% for the maths module for the year. The lecturer then told me that no-one ever got that in the history of the course. I'm not a genius at it, I just love doing it.

Kevin

yeah maths is great , as long as it has plenty of parts in it (i get bored very easily). nice grade aswell. i only got an A at GCSE which would have been about 80% i think if i remember correctly. i love the feeling of accomplishment you get when you do something really long winded and it works out alright at the end. great fun. i like to rearange equations aswell.

The thing about maths is that it's the easiest subject to get 100% in because it's either right or wrong, if you know what I mean. It's not like English where anyone rarely gets full marks. That's another thing I like about maths: It's specific, defined, and clear.

yeah, thats one of the best things about it, you can just check and definatly know if you are wrong or not and nobody can argue with you about it. its great how you can do very complex things with it aswell. e.g. i know most computer programs have alot of mathematical elements in, especialy 3d games.