Physics, Chemistry and Biology: Post your doubts here!

[zain1245780]

diamondsky help me plz ^^^

 

[diamondsky]

can anyone plz help me out with Q.6(c) of igsce chemistry theory paper oct/noc 2011? HELP ME PLZ!
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w11_qp_32.pdf

diamondsky help me plz ^^^

moles of BaSO4 = 1.398/233 =0.0006
moles of MgSO4.xH2O = 0.0006
mass of MgSO4.xH2O = 1.476/0.0006 = 246
mass xH2O = 126
x = 126/18(mass of H2O) = 7

 

[zain1245780]

moles of BaSO4 = 1.398/233 =0.0006
moles of MgSO4.xH2O = 0.0006
mass of MgSO4.xH2O = 1.476/0.0006 = 246
mass xH2O = 126
x = 126/18(mass of H2O) = 7

thanx alot!

 

[zain1245780]

diamondsky Q: 5(b)(1) of oct/nov 2010. explain that too, plz.

 

[zain1245780]

diamondsky and how did you find the mass of mass of MgSO4.xH2O ?

 

[zain1245780]

badrobot14 hey, can you answer my questions above? im in deep need! thanx.

 

[diamondsky]

diamondsky and how did you find the mass of mass of MgSO4.xH2O ?

mass is actually given
i juz found d Mr usin moles = mass/Mr formula

 

[diamondsky]

diamondsky Q: 5(b)(1) of oct/nov 2010. explain that too, plz.

variant zain1245780

 

[zain1245780]

mass is actually given
i juz found d Mr usin moles = mass/Mr formula

Q: 5(b)(1) of oct/nov 2010. explain that too, plz. thanx!

 

[zain1245780]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_32.pdf

 

[zain1245780]

diamondsky how do we find the hydrocarbon formula in Q.8(a)(iv) of june 2011 http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s11_qp_32.pdf

 

[diamondsky]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_32.pdf

dis one ws damn easy
ration methane :O2 = 1:2
so x:80
so ans is 40 cm3 ie 40/60 * 100 =66.7%

 

[diamondsky]

diamondsky how do we find the hydrocarbon formula in Q.8(a)(iv) of june 2011 http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s11_qp_32.pdf

well its actually trial n error method n u gotta try out all possibilities in d equation...wichever fits
d answer is C3H6

 

[zain1245780]

th

well its actually trial n error method n u gotta try out all possibilities in d equation...wichever fits
d answer is C3H6[/quot

well its actually trial n error method n u gotta try out all possibilities in d equation...wichever fits
d answer is C3H6

thanxs man!

 

[zain1245780]

well its actually trial n error method n u gotta try out all possibilities in d equation...wichever fits
d answer is C3H6

how to calculate Number of moles of Pb(NO3)2 in the sample........... in Q.8c JUNE 2010. http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s10_qp_32.pdf

 

[sparsha.mehta]

how to calculate Number of moles of Pb(NO3)2 in the sample........... in Q.8c JUNE 2010. http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s10_qp_32.pdf

SORRRRRRRRY WILL SOLVE TOMORRRRRRROW!!!TODAY IS PHY, NIGHT

 

[zain1245780]

SORRRRRRRRY WILL SOLVE TOMORRRRRRROW!!!TODAY IS PHY, NIGHT

DONT FORGET!!!

 

[sparsha.mehta]

DONT FORGET!!!

YUP..........SURE.I KNW ITS CHALLLENGING BUT I'LL SOLVE IT...PROMISE!!!!!!!!!

 

[zain1245780]

there is also problem with Q.6(c) of nov 2009. can you plz briefly explain me all steps? http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w09_qp_32.pdf

 

[geminisign]

Could someone please help with this chemistry question?

First variant paper, question 9ci.
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s09_qp_3.pdf

This is the answer:
silicon is limiting reagent
0.07 moles of Si and 25/160 = 0.156 moles of Br2
because 0.14 (2 × 0.07) < 0.156
If 80 used to find moles of Br2 the mark 1 and 3 still available arguments based on masses can be used

Can you please explain "because 0.14 (2 × 0.07) < 0.156 "

Thank you