Edexcel CHEMISTRY DOUBTS!!!!

[obstacle26]

Unit 1 sample assessment Paper, MCQ 3.Buckminsterfullerene is a carbon molecule with formula C60 which can trap metal ions in its structure. Which of the following compounds of buckminsterfullerene would give a line of mass/charge ratio at 837.3 in a mass spectrometer?
A Na4C60
B K3C60   
C Ca3C60
D AgC60
Answer is B , can some body explain the logic?   

[Meticulous]

m/z ratio= m/1

so calc the Mr of all compounds. It's B.

[raimunts]

One element must be O₂ for it to be an enthalpy of combustion

in the attached file

1 = standard enthalpy of combustion of A
2 = standard enthalpy of formation of A
3 = standard enthalpy of formation of B
4 = standard enthalpy of formation of C

NB. O₂ does an enthalpy of formation of 0 kJ/mol

using Hess's Law

1 = 3 + 4 - 2

just substitute in the values

Thanks a lot. Crystal clear. So it's only for enthalpy change of combustion...nothing for formation?

[raimunts]

For Edexcel AS Chemistry [New Spec] is knowledge of Unit 2 required in Unit 1? I'm asking because I've not been able to finish Unit 2 yet, and I'm wondering if it will negatively affect my Unit 1 exam. Precisely, which parts of Unit 2 are we supposed to learn when sitting for Unit 1?

[Darth Austrakast]

Well the Mechanism chapter in Unit 2 might help you with Unit 1 Organic Chemistry...........but you technically don't have to learn anything...you can just go through the topics--specially shapes of molecules,inter-molecular forces etc which are related to structure and bonding

[raimunts]

Thanx. And can u tell me, whether we have to be able to draw the structure of Sodium Chloride [ionic crytals] and diamond/graphite?

[Darth Austrakast]

yeah..............well NaCl is for sure...but you have to know the sructure of diamond and graphite as they are in the students book

[Igcseboy]

6CH01 june 2009 mcq 5 ?

[Igcseboy]

same paper MCQ 15?

[Kim]

6CH01 june 2009 mcq 5 ?

the answer is d
if u wanna know how ill tell ya

[Igcseboy]

the answer is d
if u wanna know how ill tell ya

yes i want to ... thanxzz

[Kim]

yes i want to ... thanxzz

well to calculate no of ions u need to first find no. of moles
n=m/mr=17.1/342=0.05

then u have to find the no of ions
no.of ions=0.05 x 6.02x10^23=3.01x10^22

i mole of aluminium sulphate has 2 aluminium ions and 3 sulphate ions
so as u have to find number of sulphate ions multiply the above ans by 3 and u get 9.02x10^22

[Kim]

sorry u get 9.03x10^22

[Igcseboy]

ok thanx aloot


cud u plzz do the 15th mcq also plzzz

[Kim]

ok thanx aloot


cud u plzz do the 15th mcq also plzzz

yeh sure
the answer is A
because if ge and f were to form a compound the formula wud be gef4
as ge is in group 4 and f in group 1
and the rest all are possible