Chemo P5 tips

[abrraza]

C1V1 = C2V2

2 x 125 = C2 x 250 so, C2 = 1.0 mol/dm3

isn't this the process?

sorry, you have to take 125 cm3 of the parent solution! you are absolutely correct and great spotting

credit goes 2 me :wink:

 

[zeebujha]

Very commonly asked procedures:

1. Titration:


1. acid-alkali titration

Don’t forget to:
- rinse the burette with acid
- rinse the pipette with alkali
- When emptying the pipette into the conical flask, allow it to empty under gravity, and then touch the surface of the liquid with the pipette for approximately one second
- remove funnel before titrating
- add only two drops of indicator
- swirl mixture during titration
- Wash sides of the flask regularly using a wash bottle
- titrate dropwise near end-point
- read the burette accurately (eyes horizontal, bottom of meniscus)
- record burette reading to 2 decimal places (second 0 or 5)

For better observation:
1. Place a white tile under the conical flask
2. Illuminate the burette while taking the reading

http://www.creative-chemistry.org.uk/al ... ch1-23.pdf

 

[zeebujha]

What does "jet space" refer to with regards to a burette?

 

[intel1993]

hey this is the ans 4 jun 2007 chem p5 d i)
Can u plzzz point out my mistakes ...............................


Independant Varaible: Conc of Hcl

To amke the 100 cm3 solution of 0.5 mol/dm3 the required volume will be:
M1V1=M2v2
2 into V1 = 0.5 * 100
V1= 25cm3

Measure 25 cm3 of of Hcl in pippete and transfer it to 250cm3 of volumetric flask and then fill the flaask up to the mark wid the help of distilled water

then transfer the diluted solution into 500 cm3 of beaker with the help of thistle funnel and add the measured mass of mg ribbon by the digital balance in the beaker and cover the beaker immediate with the lid having a hole from which air tight delivery tube is passing connected with 100cm3 of gas syringe...Beaker must be placed in water both t5o maintain the temp constant...Voulume of gas collected will be noted out ...

Repeat the exp using diffreent concentrations of 0.25 1.00, 1.25 1.50 etc and note the volume collected in the gas syringe.....
After collecting the readings plot a graph btw con of Hcl and volume collected...Gradient of the graph will show the rate of reaction of the exp.........

 

[zeebujha]

hey this is the ans 4 jun 2007 chem p5 d i)
Can u plzzz point out my mistakes ...............................


Independant Varaible: Conc of Hcl

To amke the 100 cm3 solution of 0.5 mol/dm3 the required volume will be:
M1V1=M2v2
2 into V1 = 0.5 * 100
V1= 25cm3

Measure 25 cm3 of of Hcl in pippete and transfer it to 250cm3 of volumetric flask and then fill the flaask up to the mark wid the help of distilled water

then transfer the diluted solution into 500 cm3 of beaker with the help of thistle funnel and add the measured mass of mg ribbon by the digital balance in the beaker and cover the beaker immediate with the lid having a hole from which air tight delivery tube is passing connected with 100cm3 of gas syringe...Beaker must be placed in water both t5o maintain the temp constant...Voulume of gas collected will be noted out ...

Repeat the exp using diffreent concentrations of 0.25 1.00, 1.25 1.50 etc and note the volume collected in the gas syringe.....
After collecting the readings plot a graph btw con of Hcl and volume collected...Gradient of the graph will show the rate of reaction of the exp.........

It would be better if you mention that you use a wash bottle or a funnel to fill the flask upto the mark (CIE won't be this specific though )
You will have to mention how you make the concentration of 1.00, 1.25 (mention relative volumes of solution + water)
Everything else is great!

 

[intel1993]

ohh thank u very much buddy i ll keep these points in my mind...................

 

[nisurju]

When using a magnesium ribbon or any dirty surface, clean it with SANDPAPER

i cudnt get it! can u please clarify it??

 

[nisurju]

For filtration:
1. If you require a great separation , use a fluted filter paper
2. If you require a quick filtration, use vacuum filtration

can u please explain me about it?

 

[nisurju]

Distillation is a great way of determining boiling point of a liquid

Melting point can be measured using a Mel Temp

what is it?

 

[zeebujha]

When using a magnesium ribbon or any dirty surface, clean it with SANDPAPER

i cudnt get it! can u please clarify it??

all I meant to say was if you have a magnesium ribbon covered with dirt, you cannot expect to react it properly with HCl!!!!!!!!! So, use sandpaper to get rid of the dirt. nothing much really, just popped up in my mind!

 

[zeebujha]

Distillation is a great way of determining boiling point of a liquid

Melting point can be measured using a Mel Temp

what is it?

we aren't expected to know about it, I think
but if you wanted to know about "Mel Temp" you could google it!

 

[WellWIshER]

GUYS JUNE O9 VARIANT 52 how to make 250 cm3 of solution of acid???? 4 marks!!!

 

[princesszahra]

GUYS JUNE O9 VARIANT 52 how to make 250 cm3 of solution of acid???? 4 marks!!!

using a burette pour 50 cm3 of an acid into a graduated flask
fill using distilled water
uptil blue mark
put the lid
and turnupside down!!

 

[samy]

can anybody please help me with the exp of may june 2010 paper52.
quest 1 part d???
cofused about making dilutions...

 

[abrraza]

Q. what volume of 2mol/dm3 H2SO4 will neutralize 70 cm3 of 3mol/dm3 of NaOH? thnx in advnx
and
Q. J10 51.... q1 part (i) how to convert energy produced interms of Delta T ... in KJ/mol for enthalpy change of neutralization... plzzzzzzzz be quick the time is running out..

 

[samy]

Q. what volume of 2mol/dm3 H2SO4 will neutralize 70 cm3 of 3mol/dm3 of NaOH? thnx in advnx

first of all find the moles of naoh using
concentration= moles / volum
dis will give conc x vol= moles
so ( dont forget to convert vol in dm3
moles of naoh = 3 x 70 / 1000 = 0.21 moles

according to the equation 2 moles of naoh react with 1 mole of h2so4 so divide the moles of naoh by 2 we will get 0.105.

these are the moles of h2so4. now again using conc= mmoles/ vol find vol that will b 0.105/2 = 0.0525 dm3...
u may convert it to cm3 that will be 0.0525 x 1000 = 52.5 cm3.!!!!

hope u get it!!

 

[samy]

for the second ques ov urx i am also not sure abt it!!

 

[zeebujha]

Drying agentrying agents absorb the moisture contents from a substance
Dehydrating agent: dehydration removes the water molecules, hence totally a new product is formed

 

[zeebujha]

If asked in an enthalpy experiment what effect does incomplete value of ethanol have on the measured enthalpy change of combustion:
1. Value decreased
2. Because less C=O bonds formed

 

[abrraza]

When required to prepare 250 cm3 of 0.5 mol/dm3 solution of a crystal of Mr 50g

First realize that we need only 250 cm3, not 1 dm3
Now in 250 cm3 there will be: 50/4 = 12.5 g of the solid

So, first add 12.5 g of solid to 50 cm3 of water in a BEAKER ( not the volumetric flask yet). Also note that the volume of water is less than 250 cm3.
Stir properly and if the solid doesn't dissolve add more water until it fully dissolves
Then transfer the solution from the beaker to a volumetric flask. Remember to rinse the beaker with water and transfer the solution to the volumetric flask
Stopper the flask and shake properly
Finally, add the required volume of water to make the solution upto 250 cm3 USE A FUNNEL OR YOU RISK OVERSHOOTING THE MARK

your LOVE~