Chemistry doubts..ask here!

[narutogirl]

[/quote]such a frequent question and i m learning it a day b4 the exam...oh my GOD...anyways as usual helped a lot[/quote]

ah its okay i went to the bio exam without with only half the syllabus >_<
so we all have our problems..lol
oh there is also questions about identification using also chromatography...for example if you could test if the sample you have is chlorophyll of if you don't know which pen belongs to who or something like that
i am going to tell you about the chlorophyll:
well you bring your unknown sample and you get something called a reference (it is like an already made chromotography paper with all the results and you could see on it the chlorophyll result)...you set up the same exp( nothing new just make the same thing as i said before) for this unknown sample...after doing the experiment you could measure the Rf value of the chrolophyll spot on the reference paper and measure on ur experiment and the one with the Rf value is the chlorophyll

OR something a bit different...you could set up two experiments...one for a chlorophyll sample and one for the unknown sample and make the experiment for both..there should be a spot that has the same hight from the baseline of both experiments that is the cholorphyll one

 

[narutogirl]

Hey guys, i have doubt with the graph questions
If they tell to sketch the graph for example 50 degree celsius which is above the temperature specified in the question then i know that the graph should be steeper but i dont know whether the concentration of a substance at the end of the reaction should be same or not while drawing the graph and this is the case for all conditions like when using a catalyst,using a higher concentration acid and using a acid with higher moles
:unknown:


Plz someone help me with this thing !!!
:wink:

well it depends if same volume used that means ends at same thing, there can't be more than one variable
or tell me which year in pastpaper and i will check it

 

[skinnyboyfat]

i actually came late from my vacation....the starting chapters contained in formation about chromotography...which i until now didnt pay attention...though u made my concepts and confusions clear...and after looking at my book its more clear...thanks

 

[narutogirl]

i actually came late from my vacation....the starting chapters contained in formation about chromotography...which i until now didnt pay attention...though u made my concepts and confusions clear...and after looking at my book its more clear...thanks[/quote]

its okay..about the second one it wasn't clear at all because i am kinda in a hurry, if u have any questions ask again..i hope u understood it..

 

[shan5674]

Hey another question,

You know the graph questions where they ask us to sketch a graph on the grid, in confused, how do i know when the graph is suppose to be steeper and when it is suppose to be below the original :S

HELPPP

well by knowing which reaction was faster..it depends some factors (am gonna say what makes the graph steeper)
1) the concentration of teh gradient if the other reaction had same volume but more conc. then it is steeper
2)surface the area..the larger the surface area the faster, the steeper the grave (like using the powdered form of a reactant)
3)temperature..the higher the temp..the more steeper
4)using a catalyst..steeper..(if they ask about 2 different catalysts..the one that produces a steeper curve is the better cataylst)
5)pressure, higher pressure..steeper curve

Heyy thankss

 

[HyDraZin3]

Is is like if there is volume of carbon-dioxide on y-axis den the volume of carbon-dioxide at the end will be same and graph will be steeper if we use higher temperature or powder of a metal? and if there is suppose temperature rise on y-axis then the temperature will be double on y axis and the graph will be steeper if we use powder of a metal?

 

[xIshtar]

Ahhhhh... It's so hot here.. ¬¬

Anyway enough random information, I have a question about what potassium iodide is used to test for :S..

Is is like if there is volume of carbon-dioxide on y-axis den the volume of carbon-dioxide at the end will be same and graph will be steeper if we use higher temperature or powder of a metal? and if there is suppose temperature rise on y-axis then the temperature will be double on y axis and it will be steeper if we use powder of a metal?

With the volume of CO2, the final volume produced would be the same, the line would just be steeper..
With temperature on the y-axis, the rise will still be the same, just quicker..

 

[narutogirl]

Ahhhhh... It's so hot here.. ¬¬

Anyway enough random information, I have a question about what potassium iodide is used to test for :S..

it hot here too..

i know that potassium iodide is a reducing agent used to test for oxidizing agents truns from colourless to brown

 

[xIshtar]

Ahhhhh... It's so hot here.. ¬¬

Anyway enough random information, I have a question about what potassium iodide is used to test for :S..

it hot here too..

i know that potassium iodide is a reducing agent used to test for oxidizing agents truns from colourless to brown

Cheers, what book are you using?

 

[narutogirl]

i am not using a book..my teacher's notes
although i prefer books over notes..cuz of the digrams n stuff

 

[Pernee26]

Can you please help me with Q6 ?
http://www.xtremepapers.me/CIE/Cambridge IGCSE/0620 - Chemistry/0620_s09_qp_6.pdf

Thanks !

 

[xIshtar]

i am not using a book..my teacher's notes
although i prefer books over notes..cuz of the digrams n stuff

Ahh, in a computerised form?

 

[HyDraZin3]

Ahhhhh... It's so hot here.. ¬¬

Anyway enough random information, I have a question about what potassium iodide is used to test for :S..

Is is like if there is volume of carbon-dioxide on y-axis den the volume of carbon-dioxide at the end will be same and graph will be steeper if we use higher temperature or powder of a metal? and if there is suppose temperature rise on y-axis then the temperature will be double on y axis and it will be steeper if we use powder of a metal?

With the volume of CO2, the final volume produced would be the same, the line would just be steeper..
With temperature on the y-axis, the rise will still be the same, just quicker..

http://www.xtremepapers.me/CIE/Cambridg ... _qp_63.pdf
See 3.(d) question here and the answer is, the graph level is above the original one

 

[shan5674]

Can you please help me with Q6 ?
http://www.xtremepapers.me/CIE/Cambridge IGCSE/0620 - Chemistry/0620_s09_qp_6.pdf

Thanks !

These are just general chemistry questions,

anyways for the first part all you have to say is crush the berries with water and filter it
ant the second part of is just adding the indicator solution to an acid and an alkali to check if it is accurate

hope it helped

 

[xIshtar]

Can you please help me with Q6 ?
http://www.xtremepapers.me/CIE/Cambridge IGCSE/0620 - Chemistry/0620_s09_qp_6.pdf

Thanks !

Okay, basically, you need to add water, as they are water soluble. Then you use a pestle and mortar to crush them.. Then you filter off the solid berry parts, leaving the berry colouring in solution.

For part (b) You need to say that you would test it with an acid and a base, and then note that the colours must be different for it to be an effective indicator.

Is is like if there is volume of carbon-dioxide on y-axis den the volume of carbon-dioxide at the end will be same and graph will be steeper if we use higher temperature or powder of a metal? and if there is suppose temperature rise on y-axis then the temperature will be double on y axis and it will be steeper if we use powder of a metal?


http://www.xtremepapers.me/CIE/Cambridg ... _qp_63.pdf
See 3.(d) question here and the answer is, the graph level is above the original one

Ahhh.. You didn't explain that it was with different masses added, as the rate of reaction is greater, the temperature change will be greater, and thus the line will be above..

 

[Pernee26]

Can you please help me with Q6 ?
http://www.xtremepapers.me/CIE/Cambridge IGCSE/0620 - Chemistry/0620_s09_qp_6.pdf

Thanks !

These are just general chemistry questions,

anyways for the first part all you have to say is crush the berries with water and filter it
ant the second part of is just adding the indicator solution to an acid and an alkali to check if it is accurate

hope it helped

Thanks !
Chemistry is really not my thing :%)

 

[HyDraZin3]

what different masses? The difference was, the metal was just powdered

 

[xIshtar]

what different masses? The difference was, the metal was just powdered

The graph is plot with temperature change against different masses of zinc used.. So when it is powdered, the temperature rise will be greater.

 

[HyDraZin3]

Can u just tell me when the level of the graph will be higher and when the level of the graph will be of same level at the end on y-axis?

 

[lavanyamane]

http://www.xtremepapers.me/CIE/Cambridg ... 6_qp_6.pdf
Q. 3(e)(iii) ?