Uc Preparation of Reagents

Preparation of solutions for mandatory experiments and

specified demonstrations

Safety note

It is essential to be familiar with the hazards associated with the particular chemicals

used to make up each of the solutions needed. The following Department of

Education and Science publications are particularly useful;

‘Safety in School Science’ (second edition 2002)

‘Safety in the School Laboratory’ (second edition 2002).

Another very useful resource in this regard is the ‘Chemistry Mandatory Experiments’

CD-ROM produced by the Leaving Certificate Chemistry Support Service, under the

auspices of the Physical Science Initiative.

1

Preparation of reagents

Distilled or deionised water should be used in making up all of these solutions.

Chapter 1

Page 11 – specified demonstration

All necessary reagents can be used as purchased.

Chapter 3


All reagents needed can be used as purchased.

Chapter 4

Page 42 – mandatory experiment




Chapter 5

Pages 71 to 74 – mandatory experiment

Chlorine solution:

Add 100 cm3 of commercial bleach to 500 cm3 of water. In a fume-cupboard, add

concentrated hydrochloric acid drop by drop, with constant stirring, until a drop of the

solution is just acid to litmus. This solution must be freshly prepared.

Bromine solution:

In a fume-cupboard, shake 0.5 cm3 bromine with 100 cm3 water. Store in a tightly

stoppered brown bottle.

Iodine solution:

2

Dissolve 20 g of potassium iodide in 500 cm3 of water. Add about 10 g of iodine

crystals, dissolve and make up to 1 litre with water.

Sodium chloride solution (approximately 0.2 M):

Dissolve about 12 g sodium chloride in water and make up to 1 litre with water.

Sodium bromide solution (approximately 0.2 M):

Dissolve about 20 g sodium bromide in water and make up to 1 litre with water.

Potassium iodide solution (approximately 0.2 M ):

Dissolve about 33 g potassium iodide in water and make up to 1 litre with water.

Iron(II) sulfate solution (approximately 0.2 M):

Dissolve 11.2 g of iron(II) sulfate crystals in 100 cm3 of water containing 2 cm3 of

concentrated sulfuric acid, and dilute to 200 cm3 with water. This solution must be

freshly prepared.

Iron(III) chloride solution (approximately 0.2 M):

Dissolve 11 g of hydrated iron(III) chloride in 100 cm3 of water containing 4 cm3 of

concentrated hydrochloric acid, and dilute to 200 cm3 with water.

Sodium sulfite solution (approximately 0.2 M):

Dissolve 5.2 g of sodium sulfite in 100 cm3 of water, and dilute with water to 200

cm3. This solution must be freshly prepared.

Sodium hydroxide solution (approximately 1 M):

Dissolve 10 g of sodium hydroxide pellets in 200 cm3 of cold water and make up to

250 cm3 with water.

Silver nitrate solution (approximately 1 M):

Dissolve 4 g of silver nitrate crystals in water, and make up to 250 cm3 with water.

Store in a brown bottle. This solution is best freshly prepared and in very small

quantities.

3

Barium chloride solution (approximately 0.2 M):

Dissolve about 40 g barium chloride in water, and make up to 1 litre with water.

Dilute hydrochloric acid solution (approximately 2 M):

In a fume-cupboard, add about 170 cm3 of concentrated hydrochloric acid slowly,

with stirring, to about 500 cm3 of water, and make up to 1 litre with water.

Dilute ammonia solution (approximately 3 M):

In a fume-cupboard, dilute 40 cm3 of concentrated ammonia solution to 250 cm3

with water.


Acidified copper(II) sulfate solution (approximately 0.1 M):

Dissolve 5 g of hydrated copper(II) sulfate (CuSO4.5H2O) in about 100 cm3 water and

make up to 200 cm3 with water. Carefully add 20 cm3 of concentrated sulfuric acid.


2 M hydrochloric acid solution:

In a fume-cupboard, add about 170 cm3 of concentrated hydrochloric acid slowly,

with stirring, to about 500 cm3 of water, and make up to 1 litre with water.


0.5 M sodium sulfate solution:

Dissolve 161 g of hydrated sodium sulfate (Na2SO4 .10H2O) in enough water to make

1 litre of solution.


0.5 M potassium iodide solution:

Dissolve about 83 g potassium iodide in water and make up to 1 litre with water.

Chapter 6


4

Part (a)

Sodium carbonate solution (approximately 0.5 M):

Dissolve 143 g of hydrated sodium carbonate (Na2CO3.10H2O) in water to make 1

litre of solution.

Sodium hydrogencarbonate solution (approximately 0.5 M):

Dissolve 42 g of sodium hydrogencarbonate in water to make 1 litre of solution.

Dilute hydrochloric acid (approximately 3 M):

In a fume-cupboard, add 255 cm3 of concentrated hydrochloric acid slowly, with

stirring, to about 500 cm3 of water, and make up to 1 litre with water.

Limewater:

Add about 200 g of calcium hydroxide to 2.5 litres of water. Shake vigorously at

intervals over a period of time and finally allow to settle. Decant off the clear

limewater solution from above the undissolved solids. Top up the container with

water and repeat the process.

Magnesium sulfate solution (approximately 0.25 M):

Dissolve 15.4 g of hydrated magnesium sulfate (MgSO4.7H2O) in enough water to

make 250 cm3 of solution.

Part (b)

Sodium sulfate solution (approximately 0.1 M):

Dissolve 32.2 g of hydrated sodium sulfate (Na2SO4 .10H2O) in enough water to make


Sodium sulfite solution (approximately 0.5 M):

Dissolve 126 g of hydrated sodium sulfite (Na2SO4 .10H2O) in enough water to make


5

Barium chloride solution (approximately 1 M):

Dissolve about 240 g barium chloride in water, and make up to 1 litre with water.

Dilute hydrochloric acid (approximately 3 M):



Part (c)

Sodium chloride solution (approximately 0.1 M):

Dissolve 5.85 g of sodium chloride in enough water to make 1 litre of solution.

Silver nitrate solution (approximately 0.1 M):



quantities.

Dilute ammonia solution (approximately 3 M):


with water.

Part (d)

Potassium nitrate solution (approximately 0.1 M):

Dissolve 10.1 g of potassium nitrate in enough water to make 1 litre of solution.

Iron(II) sulfate solution:

Dissolve 140 g of iron(II) sulfate crystals in 300 cm3 of water containing 5 cm3 of

concentrated sulfuric acid, and dilute to 500 cm3 with water. This solution must be

freshly prepared.

Part (e)

6

Disodium hydrogenphosphate(V) solution (approximately 0.03 M):

Dissolve 11.81 g of disodium hydrogenphosphate(V) in enough water to make 1 litre

of solution.

Ammonium molybdate reagent:

Dissolve 4.5 g of ammonium molybdate [(NH4)6Mo7O24.4H2O] crystals in a solution

made from 4 cm3 0.88 ammonia solution and 6 cm3 deionised water. Add to this 12 g

ammonium nitrate. Dilute with deionised water to 100 cm3 in a volumetric flask.

Immediately before use, acidify with 1.5 cm3 of concentrated nitric acid per 10 cm3

ammonium molybdate solution.







Chapter 8









7

Chapter 11




Hydrochloric acid solution (approximately 0.2 M):

In a fume-cupboard, add about 17 cm3 of concentrated hydrochloric acid, with

stirring, to about 500 cm3 of water, and make up to 1 litre with water. Stopper, and

mix thoroughly.

0.1 M sodium carbonate solution:

Using a balance, measure accurately 10.6 g of pure anhydrous sodium carbonate on a

clock glass. Transfer to a beaker containing about 200 cm3 of deionised water. To

ensure that all the sodium carbonate is transferred, use a wash bottle to rinse the clock

glass with deionised water, and add the rinsings to the beaker. Stir the mixture with a

stirring rod until the sodium carbonate has fully dissolved. Using a wash bottle, wash

off the solution on the stirring rod with deionised water into the beaker. Pour the

solution through a clean funnel into a 1 litre volumetric flask. Using a wash bottle,

rinse out the beaker several times with deionised water, and add the rinsings to the

solution in the flask. Rinse the funnel with deionised water, allowing the water to run

into the flask. Carefully make up the volume to 1 litre with deionised water. Stopper

the flask and invert it several times to ensure a homogeneous solution


0.1 M hydrochloric acid solution:

Use ampoules of 1 M HCl and dilute 10 cm3 to 100 cm3 with deionised water.

Sodium hydroxide solution (approximately 0.1 M):

Dissolve 4 g of sodium hydroxide pellets in 50 cm3 of cold water and make up to 1

litre with water.

8

mandatory experiment

0.1 M sodium hydroxide solution:

Use ampoules of 1 M NaOH and dilute 10 cm3 to 100 cm3 with deionised water.


0.1 M hydrochloric acid solution:

Use ampoules of 1 M HCl and dilute 10 cm3 to 100 cm3 with deionised water.

Chapter 12


0.1 M ammonium iron(II) sulfate solution:

Weigh accurately 39.2 g of ammonium iron(II) sulfate crystals in a small beaker and

dissolve them in a small amount of dilute sulfuric acid. Transfer the solution to a 1000

cm3 volumetric flask. Wash out the beaker with deionised water and add the washings

to the volumetric flask. Add about 200 cm3 of dilute sulfuric acid to the volumetric

flask and then bring the total volume to 1 litre using deionised water. The bottom of

the meniscus should be resting on the mark. Stopper the volumetric flask and invert

several times.

Potassium manganate(VII) solution (approximately 0.02 M):

Dissolve about 3.2-3.25 g of potassium manganate(VII) in about 1 litre of deionised

water, and allow the solution to stand overnight. Filter the solution through glass wool

in a funnel. The solution should be stored under cool conditions in a clean dark glass

bottle.

Dilute sulfuric acid (approximately 1.5 M):

Add 85 cm3 of concentrated sulfuric acid slowly to about 700 cm3 of deionised water

containing about 20 ice cubes. Stir the mixture, and make up the volume with water to

1 litre in a volumetric flask. Stopper the volumetric flask and invert several times.


Potassium manganate(VII) solution:

9

Potassium manganate(VII) is not a primary standard. It is therefore not possible to

make up solutions of exact concentration directly from the solid reagent. Instead a

solution must be made up of approximately the required concentration and

standardised prior to use. The potassium manganate(VII) solution for this experiment

can be standardised in mandatory experiment 4.5.

An approximately 0.005 M solution of potassium manganate(VII) solution may be

made up as follows:

Measure out 1.58 g of potassium manganate(VII) into a beaker. Add about 500 cm3 of

deionised water. Stir and warm gently to dissolve the crystals. Pour the solution into a

2 litre volumetric flask. Add more water to the beaker to dissolve any remaining

crystals of potassium manganate(VII). Transfer the solution formed, with washings, to

the volumetric flask. Repeat this process until all crystals have been dissolved and

transferred to the volumetric flask. Carefully fill the flask to the calibration mark with

deionised water. Stopper the flask and shake to ensure a homogeneous solution.

1.5 M sulfuric acid solution:





0.02 M potassium iodate solution:

Add 4.28 g potassium iodate to about 600 cm3 water in a beaker, and stir to dissolve.

Transfer the solution to a 1000 cm3 volumetric flask. Wash out the beaker with

deionised water and add the washings to the volumetric flask. Then bring the total

volume to 1000 cm3 using deionised water. Stopper the volumetric flask and invert

several times.

10

0.5 M potassium iodide solution:

Dissolve 83 g potassium iodide in water and make up to 1 litre with water.

Dilute sulfuric acid:




Sodium thiosulfate solution (approximately 0.12 M):

Dissolve 30 g of sodium thiosulfate in boiled deionised water and make the solution

up to 1 litre using a volumetric flask. To increase the stability of the solution add 0.1

g of sodium carbonate.

Starch indicator solution:

Pour, with stirring, a paste containing 1 g starch and a little cold water into 100 cm3 of

boiling water. Boil for two minutes, and allow to cool. The solution should be stored

in stoppered bottles.


0.l M sodium thiosulfate solution:

Dissolve 15.8 g of anhydrous sodium thiosulfate in boiled deionised water and make

the solution up to 1 litre using a volumetric flask. To increase the stability of the

solution, add 0.1 g of sodium carbonate.









11

Chapter 13

Page 241 - specified demonstration

Methane:

Natural gas, if available, can be used, as it contains methane. Otherwise, liquid

petroleum gas (LPG), which contains propane and butane, which have similar

solubility properties to those of methane, can be used.

Ethene:

Ethene can be prepared from ethanol, as described on page 338.

Ethyne:

Ethyne can be prepared from calcium dicarbide as described on page 243.


Acidified copper(II) sulfate solution:

Prepare 500 cm3 of a saturated solution of copper(II) sulfate pentahydrate

(CuSO4.5H2O). Carefully add 10 cm3 of concentrated sulfuric acid.

Limewater:





Acidified potassium manganate(VII) solution:

Mix 10 cm3 of approximately 0.02 M KMnO4 with 20 cm3 of dilute H2SO4.

Bromine water:

12






3M hydrochloric acid:




Hydrochloric acid solution (1 M):


stirring, to about 1 litre of water and make up to 2 litres in a volumetric flask with

deionised water. Stopper the flask, and invert the flask a number of times to ensure

thorough mixing.

Sodium hydroxide solution (1 M):

Dissolve 80 g of sodium hydroxide pellets in 800cm3 of cold water and make up to 2

litres in a volumetric flask with deionised water. Stopper the flask, and invert the

flask a number of times to ensure thorough mixing.

Chapter 14

Page 271 - mandatory experiment



0.1 M sodium thiosulfate solution:

Dissolve 25 g of sodium thiosulfate in boiled deionised water and make the solution



13

Dilute hydrochloric acid (3M):




0.05 M sodium thiosulfate solution:

Dissolve 12.5 g of sodium thiosulfate in boiled deionised water and make the solution
















Chapter 15



14

specified demonstration










Chapter 16


Saturated sodium chloride solution (brine):

Add sodium chloride to water, with constant stirring, until no more will dissolve. A

magnetic stirrer is very useful when doing this.


Limewater:





Bromine water:



15

Acidified potassium manganate(VII) solution:

Mix 10 cm3 of approximately 0.02 M KMnO4 with 20 cm3 of dilute H2SO4.






Potassium manganate(VII) solution:

Dissolve about 1.5 g of potassium manganate(VII) in about 500 cm3 of deionised

water, and allow the solution to stand overnight. Filter the solution through glass wool

in a funnel. The solution should be stored under cool conditions in a clean dark glass

bottle.

Silver nitrate solution:



quantities.

Sodium hydroxide solution:

Dissolve 20 g of sodium hydroxide pellets in 200cm3 of cold water and make up to

250 cm3 in a volumetric flask with deionised water. Stopper the flask, and invert the


Aqueous ammonia solution:


with water.

Dilute nitric acid:

In a fume-cupboard, dilute 30 cm3 of concentrated nitric acid to 250 cm3 with water.

Store in a brown bottle.


16





Chapter 17


Dilute ammonia solution (approximately 1M):

Using a fume-cupboard, measure out 57 cm3 of concentrated ammonia solution in a

graduated cylinder. Add this to about 500 cm3 of deionised water in a beaker, and stir.

Pour the solution into a 1 litre graduated cylinder. Dilute to 1 litre with water. Add to

a labelled bottle and mix well.

Water/ethanol/ammonia solvent (5:2:1):

In a fume-cupboard, pour 100 cm3 of ethanol, 250 cm3 of water and 50 cm3 of 0.88

ammonia solution into a large beaker and mix well.


Dilute ammonia solution (approximately 1M):

Using a fume-cupboard, measure out 57 cm3 of concentrated ammonia solution in a

graduated cylinder. Add this to about 500 cm3 of deionised water in a beaker, and stir.

Pour the solution into a 1 litre graduated cylinder. Dilute to 1 litre with water. Add to

a labelled bottle and mix well.


35% methanol solution:

Using a fume cupboard, dilute 175 cm3 of methanol to 500 cm3 with water. Stopper,

and mix thoroughly.

60% methanol solution:

Using a fume cupboard, dilute 300 cm3 of methanol to 500 cm3 with water. Stopper,

and mix thoroughly.

Dilute sodium hydroxide solution (1 M):

17

Carefully add, in stages, 40 g of sodium hydroxide with constant stirring to about 800

cm3 of water. Continue stirring until all of the solid has dissolved. Make the solution

up to 1 litre. Stopper, and mix thoroughly.

Chapter 18




Potassium dichromate solution (0.17 M):

Dissolve 20 g of potassium dichromate in deionised water and make up to 400 cm3

with water. Stopper, and mix thoroughly.

Dilute sodium hydroxide solution (2 M):

Carefully add, in stages, 80 g of sodium hydroxide with constant stirring to about 800

cm3 of water. Continue stirring until all of the solid has dissolved. Make the solution

up to 1 litre with water. Stopper, and mix thoroughly.

Dilute sulfuric acid (2 M):




Potassium chromate solution (0.21 M):

Dissolve 16.3 g of potassium chromate in water and make up to 400 cm3 with water.

Stopper, and mix thoroughly.


Iron(III) chloride solution (0.05 M):

Dissolve 13.5 g of iron(III) chloride in about 500 cm3 of deionised water containing

about 20 cm3 of concentrated hydrochloric acid. Make the solution up to 1 litre with

water. Stopper, and mix thoroughly.

Potassium thiocyanate solution (0.05 M):

18

Dissolve 5 g of potassium thiocyanate in water. Make the solution up to 1 litre with

water. Stopper, and mix thoroughly.

Chapter 20


Dilute hydrochloric acid (3 M):



Ethanoic acid solution (5%):

Measure out 50 cm3 of concentrated ethanoic acid using a graduated cylinder.

Transfer with washings to a 1 litre volumetric flask, and dilute to the mark with

water. Stopper the flask, and invert the flask a number of times to ensure thorough

mixing.

Limewater:





Chapter 21


Ethanoic acid solution (5%):

Measure out 50 cm3 of concentrated ethanoic acid using a graduated cylinder.

Transfer with washings to a 1 litre volumetric flask, and dilute to the mark with

water. Stopper the flask, and invert the flask a number of times to ensure thorough

mixing.

Potassium iodide solution (2%):

Using an electronic balance, measure out 20 g of potassium iodide. Add the solid to

about 500 cm3 of deionised water in a beaker. Transfer with washings to a 1 litre

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volumetric flask, and dilute to the mark with water. Stopper the flask, and invert the


Diluted bleach solution:

A suitable bleach solution could be made by diluting household bleach by a factor of

between 10,000 and 100,000. It is advisable to test the suitability of this solution

before the commencement of class.


Diluted bleach solution:

A suitable bleach solution could be made by diluting household bleach by a factor of

between 10,000 and 100,000. It is advisable to test the suitability of this solution

before the commencement of class.


Water sample:

A water sample taken from river or lake water where there is obviously a significant

amount of solid matter in suspension should be used in this experiment.


Water sample:

Sea water is particularly suitable for use in this experiment.




0.01 M edta solution:

Dissolve 7.44 g of the disodium salt of edta in enough water to make exactly 2 litres

of solution. Store the solution in a stoppered plastic bottle.

20

Buffer solution (pH 10):

Add 17.5 g of ammonium chloride to 142 cm3 of 0.88 ammonia solution and make up

to 250 cm3 with water.


Manganese(II) sulfate solution: Dissolve 120 g hydrated manganese(II) sulfate in

250 cm3 of water.

Alkaline potassium iodide solution: Dissolve with warming 125 g NaOH and 37.5 g

KI in 250 cm3 of water.

0.005 M sodium thiosulfate standard solution:

Dilute 50 cm3 0.1 M sodium thiosulfate standard solution (prepared as for the

mandatory experiment on page 223) with deionised water to 1 litre using a volumetric

flask.





Chapter 23

Page 457- specified demonstration






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Chapter 24



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Uc Preparation of Reagents

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