moles

Hey guys! I'm really stuck on one problem and i'm not making you do my homework I just really don't know how to get to the bottom of it. I will write down how i did it and please tell me what i did wrong. Thanks.

'The metal nickel combines with carbon monoxide to form the compound nickel carbonyl, Ni(CO)x. When 2.95 g of nickel was warmed gently in carbon monoxide, it was converted completely into 8.55 g og nickel carbonyl. Find the mass of carbon monoxide which had combined with the 2.95 g of nickel and then deduce the value of x in the formula.'

So i guess the mass of CO is 8.55-2.95= 5.60 g
Then I found out how many moles of Ni combined which is 0.05 and found out how many moles of xCO which was like 0.09. Then 5.60/0.09= 62.2 and this divided by 28 ( the Ar of CO) gave me 2. That should be x. Just that when i googled nickel carbonyl it said that its formula was Ni(CO)4 not 2. HELP PLEASE!!!!

Reply 1

vinny221

Firstly, write out the equation:

Ni + xCO==> Ni(CO)x

Then work out the number of moles of the metal and CO. 2.95/60= ~0.05 moles for the metal and (8.55-2.95)/28= 0.2 moles of CO. Then compare the ratio of metal and CO:

0.05:0.2
1 :4

Therefore, x=4 so we have Ni(CO)4.