IG Chemistry Paper 3 discussion

[VIP_93]

Here r the answers susman:

1) 4 the first question we carry out the same experiment again 4 chlorophyll pure sample and measure the Rf value and then carry the chromatography of the green solution and also measure the Rf values 4 the spots. see which Rf value matches with chlorophyll or is at the same height as the pure chlorophyll dot.

2) i did metal phosphate like u susman T3(PO4)2 but i had a different xplanation.

3)the graph of ammonia is inverse

4)in the exo thingy i added the first 2 bond energies and then subtracted (2*last bond energy) from it

5)groups in lactic acid are alcohol and carboxylic acid.and the compound which contains this type was fats or esters

6)in the PLA i wrote its biodegradable and doesnt give out toxic fumes like petrol
 
WAT IS THAT INDICATOR question u r discussing?
if it is that ques that has 1 mark then PH meter AND indicator are correct

[chakrit_m]

"for the indicator question..i wrote pH meter........i know it's wrong..but at least i wrote something...who knows..i might get it right anyway.......and for the Aluminium question i didnt balance it...so i think i got 1 for a non balanced equation instead of 2..."

dude.. dip a pH meter is 100% correct..!

Its 100% wrong PH meter is an indicator .they said how would you test if the 2 something is acidic without an indicator ....test: add any metal sodium for example ...results: hydrogen gas revolves....-rep me if am wrong and +rep me if am right 

Same answer 555

[amy.mym]

No indicator is wrong

It was stated in the question " Other than an indicator "

So I guess a test will be fair

and for the exothermic thing

Guys you don't do that multiplication thing

I actually studied this particularly for the IGCSE Course

You add the bonds for H---H and F----F that are stated

You add them and the no. will be higher than the H----F in the table, so if it is higher than its exothermic

I studied that from an IGCSE book specially designed by Cambridge

[Triple_A]

Damn......i wrote metal T was lead so it becomes Lead Phosphate!!>>>>>>>>STRANGE RIGHT
Also i did describe how it formed
Hope I did Well
aquarian93@ how come u wrote pH meter and he said beside using indicator!!
To measure pH u must add universal indicator right?!!

[VIP_93]

i thought u were talking abt another ques
if it is the test 4 organic acid then ya indicator is wrong, i wrote adding a carbonate, it will give effervacences that will turm lime water milky

i thought u r talking abt another ques, the one were they want us to differentiate between the strong and weak acid

[sweetest angel]

what about the chlorophyll question?....the first one where it says *how can you show that this green solution contains chlorophyll*?...and the second one that has 3 marks!...*expain the role of chlorophyll*?...

u add iodine it turns black, i wrote stuff like photosynthesis, and gives it its colour, and absorbs light etc, last time i read bout chlorophyll was years ago lol

for the chlorophyll u were supposed 2 do reference chromotography nt an idone test.
its chem nt bio plus chlorophyll dsnt hve starch thus dsnt turn iodine into anytin' !!
-__-"

[posten]

1-WASHING THE PRECIPtate to remove impurities and get pure salt
2-heating in an oven to evaporate water and drying the salt
3-t3po4, because 18.0cm3 of T completely reacted with 6.0cm3 of po4 (from graph) there fore 18 is three times 6 .................
4-last page
i-the emperical formulae was Mg3N2
ii-silicon was limiting reagent
iii-0.08 moles

[posten]

he said beside using indicator
so u should add a carbonate like calcium carbonate bubble the gas produced through lime water turns milky white

[amy.mym]

 

plus chlorophyll dsnt hve starch thus dsnt turn iodine into anytin' !!0

exactly LOOOL

[VIP_93]

for the bond energies they were H----H and F----F and 2H----F
we add the bond energies for H----H and F----F
then we multiply 2 by H----F
then we subtract (H----H + F----F)- (2*H---F)
the ans will be negative

[Triple_A]

For the pure chlorophyll sample...how to check if grass contained chlorophyll
i wrote:"Apply pure sample of chlorophyll on chromatogram paper and place in solvent,allow to rise and then match the dyes with tht of grass sample...!! Is tht correct?!!!!

[sweetest angel]

"for the indicator question..i wrote pH meter........i know it's wrong..but at least i wrote something...who knows..i might get it right anyway.......and for the Aluminium question i didnt balance it...so i think i got 1 for a non balanced equation instead of 2..."

dude.. dip a pH meter is 100% correct..!

Its 100% wrong PH meter is an indicator .they said how would you test if the 2 something is acidic without an indicator ....test: add any metal sodium for example ...results: hydrogen gas revolves....-rep me if am wrong and +rep me if am right 

I ADDED A CARBONATE: GAS GIVEN OFF WHEN PASSED THROUGH LIME WATER TURNS IT MILKY...EH?
AND FOR THE BOND ENERGY ITS PRODUCT ENERGY _ REACTANT ENERGIES NT DA OPPOSITE
THUS POSITIVE ANSWER 'N RXN IS EXOTHERMIC!!

[sweetest angel]

For the pure chlorophyll sample...how to check if grass contained chlorophyll
i wrote:"Apply pure sample of chlorophyll on chromatogram paper and place in solvent,allow to rise and then match the dyes with tht of grass sample...!! Is tht correct?!!!!

its refrence chromotography so urs is soo close 'n yeh may b correct

[qwert101]

"for the indicator question..i wrote pH meter........i know it's wrong..but at least i wrote something...who knows..i might get it right anyway.......and for the Aluminium question i didnt balance it...so i think i got 1 for a non balanced equation instead of 2..."

dude.. dip a pH meter is 100% correct..!

Its 100% wrong PH meter is an indicator .they said how would you test if the 2 something is acidic without an indicator ....test: add any metal sodium for example ...results: hydrogen gas revolves....-rep me if am wrong and +rep me if am right 

I ADDED A CARBONATE: GAS GIVEN OFF WHEN PASSED THROUGH LIME WATER TURNS IT MILKY...EH?
AND FOR THE BOND ENERGY ITS PRODUCT ENERGY _ REACTANT ENERGIES NT DA OPPOSITE
THUS POSITIVE ANSWER 'N RXN IS EXOTHERMIC!!

negative answer is exothermic and I also said carbonate- if u said metal or metal oxide it would also react with water hence not correct

[sweetest angel]

1-WASHING THE PRECIPtate to remove impurities and get pure salt
2-heating in an oven to evaporate water and drying the salt
3-t3po4, because 18.0cm3 of T completely reacted with 6.0cm3 of po4 (from graph) there fore 18 is three times 6 .................
4-last page
i-the emperical formulae was Mg3N2
ii-silicon was limiting reagent
iii-0.08 moles

yup all those r rit i tink...although i got da MG1.5N1
i knw u cnt gt a decimal ....am sooo stupidish