CheMistry

[SAUD ASLAM]

25cm square of1.5mol/dm2 of HCL was used.
2Hcl +CaCO3----->CaCl2+h2O+CO2

How many volume of carbon dioxide is made at RTP?

Marking Scheme says 0.9dm wheras I am getting 0.45

 

[Silent Hunter]

its which paper????????

 

[SAUD ASLAM]

October November 2005 Q5

 

[Chem_master]

hmmm.....quite difficult well according to my answer the volume is 1.8 dm3

 

[Silent Hunter]

well my answer is also 0.45 dm3 ........... what i think is that they (examiners) have not taken the number of moles of those substances into consideration......if we do the same calculation with 1 mole of HCL unlike here where 2 moles are given , we will get 0.9 dm3. OR IT MIGHT HAVE BEEN THEIR MISTAKE!

 

[SAUD ASLAM]

Yes ExamIners Is Wrong thistime

 

[bikermicefrmars]

Yup...examiners can be wrong!

I also got 0.45mol

@chemmaster....ohh bhai 1.8 kidhar se?

 

[UxaiR]

yes there is a Problem in the marking scheme the answer is 0.45 dm^3

25cm square of1.5mol/dm2 of HCL was used.
2Hcl +CaCO3----->CaCl2+h2O+CO2

How many volume of carbon dioxide is made at RTP?

Marking Scheme says 0.9dm wheras I am getting 0.45

Saud it's Volume so it should cm CUBE and dm^3

NOT

Cm Square and dm^2

 

[UxaiR]

hmmm.....quite difficult well according to my answer the volume is 1.8 dm3

Chemistry Master what happened to you ! :shock:

your Answer is not even close to the actual answer !

please show me the method you adopted to carry out the answer so that i could point out where you did the mistake

 

[Chem_master]

well calculating the mols of HCL
1.5=mols/0.025
mols=0.0375
mols of CO2= 0.01875
mols of CO2=vol/24dm3
vol of CO2 = 0.45 dm3.......oh my bad i thnk so my calculator had gone down......srryyy... :|

 

[SAUD ASLAM]

yes there is a Problem in the marking scheme the answer is 0.45 dm^3

25cm square of1.5mol/dm2 of HCL was used.
2Hcl +CaCO3----->CaCl2+h2O+CO2

How many volume of carbon dioxide is made at RTP?

Marking Scheme says 0.9dm wheras I am getting 0.45

Saud it's Volume so it should cm CUBE and dm^3

NOT

Cm Square and dm^2

Ya,kabhi kabhi ho jata hai

 

[UxaiR]

No problem i was just making you little conscious
these little things are not tolerated by Cambridge so be careful Next time

 

[Meesam]

hmmm>>>....eXAMNER IS WRONG THIS TIME
mOLES of HCL:
0.0375

Volume of CO2:
0.01875*24dm^3=0.45dm^3

 

[Silent Hunter]

donno how examiners can be wrong but they are this time

 

[UxaiR]

donno how examiners can be wrong but they are this time

they can , they too are humans Just like Us
and i have Seen mistakes of these types in marking Schemes

 

[Silent Hunter]

I have seen too .................. but still........ they are very rare

 

[Chem_master]

naa....examiners r write.....there shud be some other point that we r missin...

 

[Nibz]

Examiners can be wrong sometimes, but when they are, they do mention their mistake!!

 

[XPFMember]

25cm square of1.5mol/dm2 of HCL was used.
2Hcl +CaCO3----->CaCl2+h2O+CO2

How many volume of carbon dioxide is made at RTP?

Marking Scheme says 0.9dm wheras I am getting 0.45

I just viewed the mark scheme..and i've found the mistake...
we need to divide the no. of moles of HCl by 2 to get the no. of moles of CO2 since as per the eqn. 2 moles of HCl gives 1 mol. of CO2...and this is what nt done in the marking scheme