Qualification > Sciences
Chemistry Help HERE ONLY !!
asus:
u guys...help me with this question..
ppr3 june 04 7 b) ii
heat619:
--- Quote from: Ibiza279 on May 31, 2009, 05:26:06 pm ---
--- Quote from: heat619 on May 31, 2009, 05:18:56 pm ---Is the pressure for the Contact Process 10 atm or 20 atm, cuz the mark scheme says 10 but the book says 20 :S
--- End quote ---
huh we learnt it was 1 atp not 10 or 20 n i checked wikipedia too they say its 1-2 atp so the rite answer is 1 atmospheric pressure
--- End quote ---
so its under normal pressure?
nid404:
--- Quote from: thukon on May 31, 2009, 05:31:13 pm ---@shogun. CaCO3= 40+12+16+16+16= 100
Number of moles of CaCO3 = 0.3/100= 0.003
Number of moles of HCL = 1 mol per dm3, and 1000cm3 = 1 dm3. 5/1000= 0.005
The reaction needs 1 mol of CaCO3 and 2 mols of HCl. So the HCl needs to be double the the CaCO3, but here there isnt enough, because the CaCO3 is 0.003, and the HCl needs to be 0.006, but its only 0.005. So CaCO3 is in excess.
I was kinda confused myself doing the question. Check with the mark scheme and tell me if im correct. If i am, +rep me PLZ. I REALLY NEED IT!!
--- End quote ---
ur right and i +repped u in the morning..it was -8.....there's sumthin wrong...but ill do it again
Ibiza279:
--- Quote from: thukon on May 31, 2009, 05:31:13 pm ---@shogun. CaCO3= 40+12+16+16+16= 100
Number of moles of CaCO3 = 0.3/100= 0.003
Number of moles of HCL = 1 mol per dm3, and 1000cm3 = 1 dm3. 5/1000= 0.005
The reaction needs 1 mol of CaCO3 and 2 mols of HCl. So the HCl needs to be double the the CaCO3, but here there isnt enough, because the CaCO3 is 0.003, and the HCl needs to be 0.006, but its only 0.005. So CaCO3 is in excess.
I was kinda confused myself doing the question. Check with the mark scheme and tell me if im correct. If i am, +rep me PLZ. I REALLY NEED IT!!
--- End quote ---
listen to check the mole ratio u dn need to check the moles in the chemical equation.
n as u get the answer 0.005 which is greater than 0.003 HCl is in excess believe me :)
n to get the volume of CO2 u gotta give me the complete balanced chemical equation first.
n yh heat619 its under normal pressure
effigs:
--- Quote from: Shogun on May 31, 2009, 05:24:25 pm ---here it is
(ii)one piece of marble 0.3g, was added to 5cm3 of hydrochloric acid, concentration 1.00 mol/dm3. which reagent is in excess? give reason for your answer.
mass of one mole of CaCO3 =100g
number of moles of CaCO3= .................................................................
number of moles of HCl=.......................................................
regent in excess is ...........................................................
reason....................................................................
[4]
(iii) use your answer to (ii) to calculate the maximum volume of carbon dioxide produced measured at r.t.p.
...[1]
explain to me what u have to do, plz dont just give me the answer, do explain every part on how to find the excess.
Thanks
--- End quote ---
number of moles of CaCO3= 0.003 (because mass of calcium carbonate over molecular mass of calcium carbonate = 0.003)
number of moles of HCl = 0.005 (because number of moles= volume (in dm3) x concentration =0.005)
reagent in excess= CaCO3
reason= beacuse as the mole ratio (in the equation on the previous page) is 1:2:1:1:1, the reaction would require HCl of two times the moles of CaCO3 (i.e 0.003 x 2 = 0.006) and since we have 0.005 moles of HCl which is lesser than required, CaCO3 is in excess [make sense??]
max. volume of carbon dioxide produced= 0.06 (because as we have 0.005 moles of HCl we have to work with it to find the number of moles of CO2 (mole ratio) and then times it by 24 [as per the formula] to get the answer)
well hope that helped...
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version