Leeming SHS Yr 11 Chemistry
STAWA Exp 20
Student’s Name:
Date :
Preparation and properties of ammonia - NH3 (g)
Background
Ammonia is used as a cleaning agent in household ammonia solution, as a cheap
base in industry, in the manufacture of fertilizers, dyes and explosives. In this
experiment the preparation and properties of ammonia will be investigated.
Equipment and chemicals
250 mL conical flask with flexible
gas delivery tube fitted into a rubber
stopper
3 large test tubes with stoppers
ammonium chloride – NH4Cl - 4g
1 medium test tube
(to test a solution)
stirring rod
concentrated HCl – bottle
(test fumes)
R.O. water – wash bottle
test tube rack
universal indicator
hot plate
red and blue litmus paper
retort stand and clamp
(to stabilize the reaction flask)
wax taper (or wooden splint)
calcium hydroxide – Ca(OH)2 - 3 g
Safety
•
•
•
•
Ammonia has an irritating-choking odour.
Avoid inhaling the ammonia gas.
Prepare and test ammonia gas in the fume cupboard.
Concentrated hydrochloric acid is very corrosive ad must be handled with
care.
• If any concentrated hydrochloric acid comes into contact with your skin or
eyes, immediately wash the affected area with copious quantities of water.
Ask for help.
International safety card information
hydrochloric acid - http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc01/icsc0163.htm
ammonium chloride - http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc10/icsc1051.htm
calcium hydroxide - http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc04/icsc0408.htm
ammonia - http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc04/icsc0414.htm
harmful – NH4Cl
STAWA20.DOC
Adapted from STAWA Exp 20
HCl
NH3 , HCl
HCl , NH3
Page 1
Leeming SHS Yr 11 Chemistry
STAWA Exp 20
Procedure
Gas production
1.
Set up the gas generating equipment to collect the ammonia by the downward
displacement of air as shown in the diagram below.
ammonia gas
air displaced downwards
by ammonia gas
a few drops of RO water
ammonium chloride + calcium hydroxide
low heat
hot plate
2.
Clamp the reaction flask (to prevent accidental spillage)
3.
Place about 4 g of ammonium chloride – NH4Cl and 3 g of calcium hydroxide –
Ca(OH)2. Add a few drops of RO water, but not to much. Mix the damp
powder with a stirring rod. Replace the gas collection stopper and tubing.
4.
Use a hotplate to gently heat the reaction flask. Collect three test tubes of
ammonia gas. You can tell when the test tube is full by holding a piece of
moist red litmus paper at the mouth. It turns blue when the test tube is full.
Stopper each test tube and place in a test tube rack.
STAWA20.DOC
Adapted from STAWA Exp 20
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Leeming SHS Yr 11 Chemistry
STAWA Exp 20
Gas testing
5.
Hold the stopper from a bottle of concentrated HCl near the gas delivery tube
and record your observations.
6.
Half fill a test tube with RO water and add 3 drops of universal indicator.
Bubble some ammonia gas through the solution and not the colour change.
7.
After the reaction flask has cooled down, carefully wash it out with plenty of
water.
8.
Use the first test tube of ammonia to observe its colour and carefully detect its
odour.
9.
Into the second test tube, place a lighted wax taper (or wooden splint).
10.
Remove the stopper from the third test tube, quickly add 1 mL of water and
replace the stopper. Shake the test tube, remove the stopper and add small
pieces of red and blue litmus paper. Record your observations.
11.
Safely dispose of all spent chemicals and clean the work area for the next
group.
Data Sheet
NH3 - Ammonia gas
observations
colour
odour
universal indicator
litmus paper
burning wax taper test
HCl (g) + NH3 (g)
STAWA20.DOC
Adapted from STAWA Exp 20
Page 3
Leeming SHS Yr 11 Chemistry
STAWA Exp 20
Processing of Results
1.
Write a balanced equation for the preparation of ammonia.
2.
List the following physical properties of ammonia –
•
colour
•
odour
•
density
•
solubility in water
•
acidic or alkaline property
•
From your observations, what can you say about the solubility of ammonia in
water?
•
Write an equation to show the reaction that takes place when ammonia
dissolves in water.
•
Does this account for the colour of the universal indicator and the litmus
paper?
3.
STAWA20.DOC
Adapted from STAWA Exp 20
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Leeming SHS Yr 11 Chemistry
STAWA Exp 20
4.
Could ammonia gas be collected using the downward displacement of water
method? Explain.
5.
Write an equation for the reaction between ammonia and hydrogen chloride.
6.
Does ammonia support combustion?
STAWA20.DOC
Adapted from STAWA Exp 20
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