Chemo P5 tips

[samy]

how do v know wen v have to find gradient?? like in oct/nov 2010 paper 53 ques 2 part d (ii)...n how does this tell us about the answer??

and can someody please tell exactly wat is a construction line??

 

[ParanoidAleveler]

how do v know wen v have to find gradient?? like in oct/nov 2010 paper 53 ques 2 part d (ii)...n how does this tell us about the answer??

and can someody please tell exactly wat is a construction line??

Construction lines are nothing but 2 perpendicular lines drawn to the graph (they form a triangle) with the hypotenuse being the straight line of the graph.
To find the gradient: y2 - y1 / x2 - x1 (where x and y are points on the graph)

for part d (ii): It is suitable for the determination of the partition coeffiicient because a straight line is obtained which passes thru the origin, with few anamolous points

 

[ParanoidAleveler]

HELP!
O/N 2009 PAPER 5.
Question 2 (e)
can someone pleaseee explain the reasons? :unknown:

 

[samy]

how do v know wen v have to find gradient?? like in oct/nov 2010 paper 53 ques 2 part d (ii)...n how does this tell us about the answer??

and can someody please tell exactly wat is a construction line??

Construction lines are nothing but 2 perpendicular lines drawn to the graph (they form a triangle) with the hypotenuse being the straight line of the graph.
To find the gradient: y2 - y1 / x2 - x1 (where x and y are points on the graph)

for part d (ii): It is suitable for the determination of the partition coeffiicient because a straight line is obtained which passes thru the origin, with few anamolous points

when v r asked to draw construction lines that means v have to find gradient??

 

[samy]

for part (ii) mark scheme sayx Correctly calculates the value of the gradient. This should be in
the order of 16.3/0.061. ECF incorrect intercepts.
Yes, Since the results produce a good linear/straight line graph,
the procedure is OK.
Normally a “no” answer is not acceptable. Do not accept an
unjustified “yes” answer.

so how do v know that for this v have to find gradient?

 

[ParanoidAleveler]

for part (ii) mark scheme sayx Correctly calculates the value of the gradient. This should be in
the order of 16.3/0.061. ECF incorrect intercepts.
Yes, Since the results produce a good linear/straight line graph,
the procedure is OK.
Normally a “no” answer is not acceptable. Do not accept an
unjustified “yes” answer.

so how do v know that for this v have to find gradient?

wen it says construction lines.. its always to find the gradient.

d (ii) is not related to the gradient. Its related to the shape of the graph. It asks if the experiment is reliable and we hav to answer based on our findings (i.e. the graph plotted) If the graph was say a scattered graph with no co-relation then we wud say that the experiment is NOT reliable cuz graph obtained shows no relationship b/w the variables.

 

[samy]

ohkay thanku so mush

 

[workinghard]

i could nt find da grad mine is so diff in dis ppr
can u tell me wat u plotted on bth axes n da units
thnk u so much
n dis forum is outstanding espacially wat zeebujha posted!!!
thnk u so very mucH!

 

[zeebujha]

okay guys, I think I am done with this post. If you have any experimental procedures (not calculations and graph works because I find it very difficult to explain them online) please post the question here. And sorry for not replying to some of the questions, it is just that explaining how to draw construction lines and other stuffs of Q. 2 , I just can't do them online!!!!!!

 

[ParanoidAleveler]

okay guys, I think I am done with this post. If you have any experimental procedures (not calculations and graph works because I find it very difficult to explain them online) please post the question here. And sorry for not replying to some of the questions, it is just that explaining how to draw construction lines and other stuffs of Q. 2 , I just can't do them online!!!!!!

First of all, thanks SO much for all the tips you hav mentioned! U hav NO idea how much this has helped me!

O/N 2009 PAPER 5.
Question 2 (e)

This isnt related to a graph. Well there are ratios of I : Zn. I just wanted to know whts wrong with the experiment if the ratio is too high or too low.

Thnks

 

[WellWIshER]

okay guys, I think I am done with this post. If you have any experimental procedures (not calculations and graph works because I find it very difficult to explain them online) please post the question here. And sorry for not replying to some of the questions, it is just that explaining how to draw construction lines and other stuffs of Q. 2 , I just can't do them online!!!!!!

thanks a million 4 sharing ur practical xperience.

can u please write da procedure of oct 2010 52???

 

[zeebujha]

okay guys, I think I am done with this post. If you have any experimental procedures (not calculations and graph works because I find it very difficult to explain them online) please post the question here. And sorry for not replying to some of the questions, it is just that explaining how to draw construction lines and other stuffs of Q. 2 , I just can't do them online!!!!!!

First of all, thanks SO much for all the tips you hav mentioned! U hav NO idea how much this has helped me!

O/N 2009 PAPER 5.
Question 2 (e)

This isnt related to a graph. Well there are ratios of I : Zn. I just wanted to know whts wrong with the experiment if the ratio is too high or too low.

Thnks

I am presuming "I on Y-axis and Zn on X- axis"

If ratio is too high, we can deduce that I is higher than it should be. Or it ccould also mean mass of Zn used calculated is lower than it should be. So, what could give a lower than required mass of used Zn? Well, if mass of Zn is determined by subtracting the mass of excess Zn from mass of original sample, the mass excess Zn is lower than required. That could be due to the fact that not all of the ethanol used in the washing process has been evaporated and thus the mass of ethanol adds to the mass of excess Zn.

If ratio is too low, we can similarly say that mass of excess Zn is lower than the true value. What could be causing this??Probably some of the excess Zn was lost during the drying cooling process and this could have been due to the Zn being blown out of the tube when the tube is left to dry.

These two are the only points that come to my mind right now. But if you understand the basic principle behind the increased or decreased ratio, you should be able to guess what factors result in those principles

 

[HarisShahzad]

May June 2010 paper 52 Q1(d) plz
Oct Novmember 2008 paper 5 1(c) Part 1 and 2

Plz solve these questions with proper explanation. Plz help

 

[zainrocks]

Oct/Nov 2007; Q1

In this question..do we have to measure the masses of the hydroxides such that the total moles of the hydroxides are constant? eg..mass measured such that all have 0.2 moles?

 

[ParanoidAleveler]

okay guys, I think I am done with this post. If you have any experimental procedures (not calculations and graph works because I find it very difficult to explain them online) please post the question here. And sorry for not replying to some of the questions, it is just that explaining how to draw construction lines and other stuffs of Q. 2 , I just can't do them online!!!!!!

First of all, thanks SO much for all the tips you hav mentioned! U hav NO idea how much this has helped me!

O/N 2009 PAPER 5.
Question 2 (e)

This isnt related to a graph. Well there are ratios of I : Zn. I just wanted to know whts wrong with the experiment if the ratio is too high or too low.

Thnks

I am presuming "I on Y-axis and Zn on X- axis"

If ratio is too high, we can deduce that I is higher than it should be. Or it ccould also mean mass of Zn used calculated is lower than it should be. So, what could give a lower than required mass of used Zn? Well, if mass of Zn is determined by subtracting the mass of excess Zn from mass of original sample, the mass excess Zn is lower than required. That could be due to the fact that not all of the ethanol used in the washing process has been evaporated and thus the mass of ethanol adds to the mass of excess Zn.

If ratio is too low, we can similarly say that mass of excess Zn is lower than the true value. What could be causing this??Probably some of the excess Zn was lost during the drying cooling process and this could have been due to the Zn being blown out of the tube when the tube is left to dry.

These two are the only points that come to my mind right now. But if you understand the basic principle behind the increased or decreased ratio, you should be able to guess what factors result in those principles

I get the high ratio bit, but im sorry could u explain the low ratio bit a bit more?
Shouldnt the mass of Zn be higher if the I : Zn ratio is low?

 

[zeebujha]

the mass of USED zinc is higher . That would be mass of EXCESS zinc would be lower

 

[zeebujha]

GUYS HAVE A LOOK AT THIS, ASAP!!!!!!!!!!

http://www.chemguide.co.uk/physical/bas ... ental.html

 

[HarisShahzad]

zeebujha can u plz answer my questions mentioned above. i seriously need help

 

[HarisShahzad]

i would be really grateful

 

[zainrocks]

please answer my question.oct/nov 2007; Q1..do we have to measure the masses of the hydroxides such that the total moles of the hydroxides are constant? eg..mass measured such that all have 0.2 moles?