required practicals

Question 1

ideal gas formula

Answer 1

pV= nRT

Question 2

method for making up a volumetric solution

Answer 2

-weigh sample bottle containing solid
-transfer to beaker, reweigh sample bottle and record mass difference
-add 100cm^3 distilled water and transfer to graduated flask
-wash beaker with water and add to flask until all solid is gone
-make up to the mark with distilled water and invert several times to mix

Question 3

method for diluting a solution

Answer 3

-pippette 25cm^3 of solution into graduated flask
-make up to the mark with distilled water
-invert several times to mix

Question 4

acid-base titration method

Answer 4

-rinse equipment with distilled water
-pipette 25cm^3 alkali into conical flask
-fill burette with acid to 0
-add a few drops of indicator to flask
-slowly add acid until end point is reached, swirling flask
-add drop by drop as end point is neared
-record how much acid was used and repeat titrations until you have concordant values
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Question 5

concordant results

Answer 5

within 0.10cm^3 of eachother

Question 6

rate of hydrolysis of haloalkanes method

Answer 6

-add 3 drops of each haloalkane to seperate test tubes
-add 4cm^3 0.02M silver nitrate to each test tube
-put all the test tubes in a water bath
-record how long it takes for a ppt to form in each

Question 7

order of reactivity of haloalkanes

Answer 7

iodoalkanes> bromoalkanes> chloroalkanes
ppt forms fastest in iodoalkanes

Question 8

reason for reactivity sequence of haloalkanes

Answer 8

C-I bond is weakest so is hydrolysed quickest

Question 9

halide ppt colours with AgNO3

Answer 9

Cl- white
Br- Cream
I- yellow

Question 10

method for partial oxidation of primary alcohol

Answer 10

-add 10cm^3 dilute H2SO4 , 3g potassium dichromate and 2/3 anti-bumping granules to a flask and shake
-add 1.5cm^3 primary alcohol via a pippette, shake the flask again and assemble for distillation
-gently heat until you have collected 2cm^3 of liquid in the test tube

Question 11

method for full oxidation of primary alcohols

Answer 11

-add 5cm^3 of water and 6g of sodium dichromate to a boiling tube and shake then leave to dissolve
-add 1.5cm^3 primary alcohol and 5cm^3 water and 2/3 anti bumping granules to a round bottomed flask and set up for reflux
-add 2cm^3 conc H2SO4 down the condenser followed by the sodium dichromate solution both a drop at a time
-boil on a low bunsen setting for 10 mins ensuring no vapour escapes
-arrange the equipment for distillation and collect 2-3cm^3 liquid

Question 12

method for purifying an organic liquid

Answer 12

-pour the impure product into a seperating funnel
- add sodium hydrogencarbonate, shake and release the pressure from CO2 gas
-allow the layers to seperate and run off and discard the bottom layer
-run the organic layer into a flask and add drying agent
-distill the organic liquid and collect the product