damn group 2 calculation help

hi, can anyone tell me how to do this calculation properly? i keep ending up with minus numbers, etc which clearly means i am doing it wrong

1(a)In an experiment to identify three unkown carbonates 0.500g of A,B and C, was each added in turn to an excess of hcl acid

carbonate A produced 61.0cm3 of carbon dioxide, carbonate B produced 96.0 cm3 and carbonate C produced 142.0cm3 all measure at room temperature and pressure. if all three carbonates have the general forumula of MCO3, use these values to find the relative formual mass of MCO3 and hence the relative atomic mass of M and threfore the identity of A, B and C

any replies appreciated :tsr2:

Reply 1

Artemidoros.

You could approximate molar volume to be 22.4 litres and hence use proportionality to get the number of moles of each of A, B and C (22.4 litres - 22400ml, eg. for B, 96/22400 = ?)

You could then get the Relative Molecular Mass, by dividing Mass by the number of moles you got, then, subtract the molar mass of C03 as it is consistent in each unknown, and hence work out the identity of each compound.

Reply 2

Artemidoros.

I could well be wrong. :teeth:

Reply 3

bindymackenzie

lol, well i did everything you said actually but used 24000cm3 instead of 22400, but i still got weird answers? i think may just ask my chemistry nerd friend to go over it with me tomorrow but thanks for reassuring me that my method was ok :biggrin:

Reply 4

Mth15

Use 24000 (as it says room temperature as opposed to standard).

Write the general formula:

MCO3 + 2HCl --> MCl2 + CO2 +H2O

Therefore moles of CO2 = Moles of Carbonate

Divide each volume by 24000, then use that number to divide your mass (to scale up to one mole) and minus 60 (for the carbonate) and read off the periodic table: I got Magnesium, Zinc and Barium Carbonates

Reply 5

bindymackenzie

yeah i think i did what you said - but i got different elements at the end, yours are probably a lot more likely than mine as i got barium for the first one

thanks a lot for the help though, now i know what element i should be getting :biggrin:

Related discussions

Latest

Trending

Articles for you

Edexcel A-Level Economics Paper 1 - Unofficial Mark Scheme - 18 May 2023

Try out the app

Continue on web