Chemo P5 tips

[abrraza]

can anyone explain plzzz what to do in N09 52 q1... (d)

 

[abrraza]

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

what do u mean by a new product formed on removing moisture? nd can u give an example of drying agent ?

 

[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

what do u mean by a new product formed on removing moisture? nd can u give an example of drying agent ?[
Drying simply is removing the water present in the crystal due to its treatment during the course of experiment. I have mentioned the examples of drying agent in one of my posts. An example could be silica gel

 

[zeebujha]

Errors in measuring enthalpy change:
1. Maximum temperature difficult to determine
Measure temperatures often or use a computer and datalogger to measure the temperature

2. The temperature of the solution is not uniform
Stir the solution throughout the experiment or use a magnetic stirrer



Also, even if there are no experimental error while measuring the enthalpy change of combustion of ethanol , we cannot find the accurate value of the enthalpy. The defintion of enthalpy requires formation of liquid water on combustion but in our experiment the water is being turned into vapour!!!!!!!!

 

[borntofly]

What is the formula to calculate solubility ?

Is it Mass of crystals/g x 100/ Mass of water/g ??

Can someone please post the spceimen results when KClO3 will saturate at 100 g of water?

 

[zeebujha]

How to purify an organic liquid ( such as cyclohexene) that is contaminated with acid:
1. Add NaHCO3 in excess. This reacts with the acid to neutralize it
2. Wash off the NaHCO3 from the organic liquid using water (NaHCO3 is aqueous)
3. Add drying agent to the solution to remove water
4. Distill the solution

 

[zeebujha]

What is the formula to calculate solubility ?

Is it Mass of crystals/g x 100/ Mass of water/g ??

Can someone please post the spceimen results when KClO3 will saturate at 100 g of water?

Yep that is the formula

 

[ammarelahi]

how r the concentrations to be calculated in N10 P53 Q2 ??

 

[abrraza]

Zeebujha .. plz tell something on Enthalpy change of combustion and .. a simple design fot determination..

 

[nealDSA]

Thanks A Loottt For Sharing These Notes =D (Y) !!

 

[WellWIshER]

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

I DIDNT GET DIS?>

 

[WellWIshER]

SHOULDNT IT BE 6.25 GRAMS OF SOLID

 

[abrraza]

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

I DIDNT GET DIS?>

50 grams is the total mass.. means that 1 molar mass in 1000cm3(1dm3) ... so we have to make a solution of 250cm3.. so if 50g are in 1000cm3 than 50/4=12.5g will be in 1000/4=250cm3 ... i hope u get it

 

[WellWIshER]

CHEERS!!

but do questions like these cum???


i dont gt when should we say tht independant variable is conc of an acid or volume!!

 

[zeebujha]

Zeebujha .. plz tell something on Enthalpy change of combustion and .. a simple design fot determination..

HERE YOU GO:
http://www.creative-chemistry.org.uk/al ... ch2-09.pdf

 

[zeebujha]

When asked "Which equipment should be changed so that the accuracy is improved the most?", always choose the equipment which has the highest percentage error in the experiment.

 

[zeebujha]

The volume of a polystyrene cup used in the lab is roughly 150 cm3

 

[WellWIshER]

When asked "Which equipment should be changed so that the accuracy is improved the most?", always choose the equipment which has the highest percentage error in the experiment.

highest or lowest???

 

[nisurju]

When asked "Which equipment should be changed so that the accuracy is improved the most?", always choose the equipment which has the highest percentage error in the experiment.

highest or lowest???

highest because they increase uncertainty!
the ones with low errors should be used

 

[cieko..]

You are really a great help..
Thanks A LOT..