Paper 5 Tips !! :)

[railey]

how do u put it straight in the conical flask? like u just throw it in there ? this will start the reaction immediately and u still didn't connect ur apparatus to a gas syringe so loss of oxygen (thats an error) and u wont be able to determine the rate if u do it that way. so what the mark scheme is saying is that u separate the peroxide from the catalyst by using a divided flask for example and as soon as u remove the barrier between them u can start ur stop watch and watch ur gas syringe being filled with oxygen!

Can you please draw it for me?

 

[iKhaled]

Can you please draw it for me?

you mean u wanna know how a divided flask looks like ?

 

[railey]

you mean u wanna know how a divided flask looks like ?

Yup

 

[iKhaled]

Yup

 

[iKhaled]

Yup

can u see that? u connect it to a gas syringe and once u remove the barrier between them the reaction will start and that way u will have no loss of oxygen because the syringe will be already connected

 

[railey]

can u see that? u connect it to a gas syringe and once u remove the barrier between them the reaction will start and that way u will have no loss of oxygen because the syringe will be already connected

Oh it does makes sense, Saw labelling it will just be ' a barrier to initial separate the H2O2 from the catalyst' right?
Thanks a lot bro.

 

[iKhaled]

Oh it does makes sense, Saw labelling it will just be ' a barrier to initial separate the H2O2 from the catalyst' right?
Thanks a lot bro.

yeah u can say that!

 

[AdeleintheDeep]

@kazi umayer alim

In this experiment we get a precipitate. The prediction that we're putting into test is that the moles of of the precipitated copper hydroxide increases with the increasing conc. of CuSO4.

• So keeping our hypothesis in our mind, we should know that the conc. of CuSO4 is the independent variable, which means it is in our control. Hence, you need to prepare a range of concentrations of CuSO4. You're also aware of the fact that the solutions saturates at 1.39 mol/dm3. So the range of concentrations that you prepare must not exceed 1.39 mol/dm^3. So your range is going to be 0-1.39 mol/dm^3. You need to prepare at least five diluted solutions.
• Say you're going to prepare 100 cm^3 of each of the following conc. range: 0.01, 0.05, 1.00 1.10, 1.20 and 1.39. You need to tell the examiners exactly how you're going to prepare them. Since you're given SOLID hydrated CuSO4, you're going to have to dissolve a certain mass in water. So say you want to make the 0.01 mol/dm^3 solution- you need to know how many moles are are to dissolved in a 100 cm^3 solution. So Moles= CV= 0.01*100*10^-3= 0.01 mol. So you need to dissolve 0.01 mol of hydrated CuSo4 in 100 cm^3 of water. To find out the mass= Moles*Mr= 0.01*249.6= 2.50 g. So you dissolve 2.50 g of the salt into 100 cm^3 of water to make a 0.01 mol/dm^3 solution. The rest of the concentrations are to be prepared in the same way- but you don't need to show the working. One calculation for conc. should be enough.
• After you've added the NaOH into the solution a precipitation of Cu(OH)2 will occur. You need to filter this (Or centrifuge it,and then decant).You could leave it out to dry, or add water and propanone.

Thats about it! Hope it helped!

Ashique . its probably too late now...but the moles you calculated in the 2nd bullet point should be 0.001 mol, giving a mass of 0.25g in 100cm^3 water.

 

[railey]

yeah u can say that!

Thanks Mate

 

[iKhaled]

guys how can i do the table in part 1(d) pls pls help..

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_qp_52.pdf

 

[xhizors]

lol lol

 

[minhaj89]

Measuring enthalpy change of combustion!!
Take an empty spindle weigh it and then pour any alcohol and re weigh it
setup a dry wrick and cap the spindle to avoid evaporation ofuel
take 150 cm3 metal can pour 50 cm3 water and place it over spindle on a table alike
measure the initial temp of water
light the spindle and keep measuring temperature until their is a rise of 10*C
recap spindle allow it to cool remove cap and wrick and reweigh it
substract mass after heating and before heating u'll get the mass which is burnt in excess oxygen
use q=mc4T and u'll get enthalpy change of combustion

what is a spindle? i searched but still no clue

 

[queen of the legend]

can some1 just quickly exaplain M-J 2011 v.53 ...question 2 ...about solubility in g/100g of water ....how do we exactly solve for that colomn ....pls reply soon

 

[queen of the legend]

what is a spindle? i searched but still no clue

you can use a spirit lamp contaning the fuel .....refer to m-j 2008 ....there a useful diagram in the question itself

 

[xtremeforums]

can some1 just quickly exaplain M-J 2011 v.53 ...question 2 ...about solubility in g/100g of water ....how do we exactly solve for that colomn ....pls reply soon

The mass of water: C-B
Mass of solid dissolved: D-C
Solubility: (Mass of solid x 100) / mass of water.

 

[umaima61]

Plz can u tell me mj12 question 1 partc plzzz and mj2011 question 2 do wee find solubility by taking mass of water 100 or the one we calculated

 

[pearl angel]

where is that question ?!

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_52.pdf

 

[Zari]

Asalamualikum i just wanted to ask whats the actual formula to find solubilty because i am really confused some say its is mass of solid divided by100 g of water but others say its mass of solid by mass of water into 100 can u plz tell me whats the correct formula ?jazakAllah

 

[umaima61]

The question is u have to make conc of solid cuso4 and react with naoh

 

[Soldier313]

Asalamualikum i just wanted to ask whats the actual formula to find solubilty because i am really confused some say its is mass of solid divided by100 g of water but others say its mass of solid by mass of water into 100 can u plz tell me whats the correct formula ?jazakAllah

mass of solid/mass of water x 100
as far as i know
and units are g/100g of water