As Practicals

Question 1

What is a standard solution

Answer 1

This is one where you knw the exact concentration of the solution

Question 2

Describe How a standard solution made using(Naoh as an example

Answer 2

Find out moles of sodium hydroxide usingC*V

Then work out the mass of sodium hydroxide needed in the solution

Place a weighing boat on a digital balance and weigh out the mass solid and pour it into a beaker (resign the boat and subtract the mass of the boat from the mass of the boat and the solid together to find a precise mass

Add distilled water to the beaker and stir till all the sodium hydroxide is dissolved

Pour it into a volumetric flask(250) using a funnel

Rinse the beaker and stirring road with distilled water and add this also to the flask

Fill the flask with distilled water making sure u reach the bottom of the meniscus line

Then invert the flask to make sure it’s mixed in properly

Question 3

What does a titration enable us to do

Answer 3

It allows us to find out how much acid is needed to neutralise a measure d quality of alkali

Question 4

Describe how to perform a titration

Answer 4

First use HCL to clean out the burette

Then fill it with your standard solution place a white tile and a flask under the burette( the flask contains your acid and indicator )

Do a rough titration first

Then take an initial reading to see how much alkali is in burette then allow the alkali to pour into the flask until it’s nearly finished the gently administer drop by drip

Once a colour change has occurred record the volume of your standard solution needed to neutralise the acid by minusing final reading from initial

Repeat until you have concordant results

Question 5

State the indicators used in titration and state the colour change

Answer 5

Methyl orange- yellow in acid,red in alkali

Phenolphthalein-pink in alkali and colourless in acid

Question 6

State why universal indicator isn’t used

Answer 6

The colour change is to slow/gradual

Question 7

State how you would go about measuring enthaply change (neutralisation)

Answer 7

Place 50 cm of acid in one polsystrene cup and 50cm of alkali in another cup

Using a thermometer take the temp of both solution every 30 sec for 4 minutes

Then pour one

Question 8

Why is it important to measure the temperature of the solutions in the intial four minutes

Answer 8

To make sure they remain at the same temperature or reach the same temperature

Question 9

State experimental problems with all calorimetery

Answer 9

Some of the heat is lost to surroundings

Mass of water is incorrect,some of the heat is absorbed by the container and not used in heating water

Question 10

Stat experimental problems with liquid calorimetery

Answer 10

Combustion may be incomplete so less energy is given out

Some liquid escapes by evaporation

Question 11

State how you will test for group 2 ions using the flame test

Answer 11

Dip nichrome wire into Conc HCL

Then dip the wire loop into the unknown compound

Hold the loop into a Bunsen burner

The

Question 12

Give the results of the flame test for group 2 ions

Answer 12

Calcium-brick red
Strontium-red
Barium-pale green

Question 13

Using dilute sodium hydroxide how would you test for

Group 2 metal ions

Answer 13

Barium chloride,calcium chloride,magnesium chloride and strontium chloride initially colourless

Add 10 drops of Naoh

Bacl colurless,caBr2-slight white precipitate

Mgcl2-slight white precipitate ,strontium chloride-slight white precipitate

Excess Naoh-bacl still colourless,calcium bromide slight white precipitate
magnesium chloride white precipitate,

Strontium chloride-slight white precipitate

Question 14

State how you would test for ammonium ions and state the results

Answer 14

Put red damp litmus paper in the solution

If it turns blue then ammonia is present

Question 15

How would you test for sulphate ions

Answer 15

Add dilute HCL
Followed by bacl2
If a white precipitate forms sulphate ions are present

Question 16

How would u test for Oh ions

Answer 16

Mix Naoh and ammonium chloride together and using the fumes released

See the colour change that occur when red litmus paper in the solution

If it turns blue Oh ions are present

Question 17

How would u test for carbonate ions

Answer 17

Add dilute HCL
If carbonate ions are present then efferversance is will occur as Co2 forms

It turns limewater cloudy

Question 18

How would you test for an Alkene and state the expected results

Answer 18

Add bromine water

Decolorisation occurs due to the presence of the double bond

Question 19

How would u test for a haloalkane and state the results

Answer 19

Add warm aqueous Naoh then cool
Then add nitric acid
Then add sliver nitrate

White precipitate for Chloroalkane
Cream precipitate for bromoalkane
Yellow precipitate for iodoalkane

Question 20

State how would distinguish between the results obtained with the reaction of halokanes

Answer 20

Use ammonia

White precipitate of chlorine is soluble in dilute ammonia

Cream precipitate of bromine is soluble in concentrated ammonia

Yellow precipitate of iodine is insouble in concentrated ammonia

Question 21

How would you distinguish between a primary alcohol and secondary/tertiary alcohol

Answer 21

Add dilute sulfuric acid and potassium dichromate

Primary causes it to change from orange to green

Question 22

How would you test for a carboxylic acid and state the findings

Answer 22

Add sodium carbonate

Effervescence will occur

Question 23

In reflux and distillation why are anti bumping granules added

Answer 23

This is done to prevent vigorous boiling

Question 24

Why should the condenser never be sealed in distillation and reflux of an organic product

Answer 24

As it may lead to an explosion

Question 25

In titration why is | distilled water added to the conical flask and why doesn't it affect the titration results

Answer 25

It's added to make sure acid and alkali have reacted properly It's doesn't affect titration reading as it doesn't react with the reagents

Question 26

How would u test for group 2 cations using H2SO4

Answer 26

Bacl,Cabr,Mgcl,Strontium chloride Add 10drops of H2SO4, White precipitate for Srcl2 and Bacl2 Slight white for Mgcl and Cabr ``` In excess Bacl-white precipitate Cabr-slight white Mgcl-colourless Strontium CL-white precipitate ```

Question 27

How do u test for halide ions in solids using conc H2SO4

Answer 27

Using a spatula add solid kcl to a test tube add 2-5 drops of H2SO4 Test the gas evolved with moist blue litmus paper Results effervescence and paper turns red Repeat using potassium bromide this time test the gas produced using filter paper that has been dipped in acidfied potassium dichromate Results-efferservance and brown gas produced,solution turns deep brown and red Using potassium iodide but this time test the gas using a narrow strip of paper that has been dipped in lead nitrate solution Results-solution goes red brown immediately,brown gas produced