Information
Urban climate
class
air pollutants
name
date
Air contaminants from exhaust gases of motor vehicles
Exhaust gases are hazardous to your health and should not be inhaled!
Use a fume hood or work outside.
Chemicals:
TAKE CARE: Some of the chemicals used in the experiment are harmful.
Experiment carefully and use safety equipment!
concentrated ammonia (25%) [C, N; R: 34-50; S: 26-36/37/39-45-61]
solution of silver nitrate, AgNO3 (aq), (ca. 2%)
aqueous solution of calcium hydroxide, CaOH (aq)
N, (1-naphthyl) ethylenediamine dihydrochloride [Xi; R: 36/38; S: 22]
sulfanilic acid [Xi; R: 36/38-43; S: 2-24-37]
acetic acid [C; R: 10-35; S: 1/2-23-26-45]
distilled water
Preparation of the Saltzmann-solution
This solution is used to measure nitrous acid. This forms when nitrogen oxides react with water.
Dissolve:
5g sulfanilic acid
0.050g N, (1-naphthyl)-ethylenediamine dihydrochloride
50ml acetic acid
in 800ml distilled water.
Then make the solution up to one litre in volume using distilled water. In the absence of light and air the
solution can be stored for months.
Basic materials needed for each group (you may also need other materials, it depends on how you plan
your experiment!):
3
2
2
gas-washing bottles
or alternatively: test tubes with offset extension, gas-entry tube (bent glass tube) and suitable
plug
cuvettes or small, clean test tubes of the same shape
glass syringe (with clip)
retort stands, clamps, sockets
flexible tube pieces (as connecting pieces)
bag for sample collection (see below)
flexible tube fitting the gas-entry-tube and the glass stopcock
© 2004 ESPERE-ENC / Seesing, Tausch, Universität-Duisburg-Essen; Duisburg
Worksheet
No.____a
Urban climate
class
air pollutants
name
date
Air contaminants from exhaust gases of motor vehicles
1. Preparation and sample collection of exhaust gas in freezer bags
You need sample collection bags to collect and transport your exhaust gas samples. Te best bags to use
are commercial freezer bags (without fasteners). Before using them as collection bags they have to be
modified as follows:
Materials needed for each bag:
1
freezer bag (or a thick airtight and gas-impermeable plastic bag) with a volume of 3 to 10 litres
1
tube (glass, plastic or metal) length: 15-30 cm, diameter: 25- 50 mm
broad plastic tape
1
rubber stopper (for the connection of the glass stopcock with the glass tube, see pictures 1-4)
1
glass stopcock (or glass tube with rubber hose and clamp)
picture 1
picture 2
picture 3
picture 4
Place the glass tube in the middle of the open edge of the plastic bag. Make sure it reaches well into the
bag. Seal the bag order to seal the bag by applying tape to the open edges of the bag . Then wrap
these sealed edges around the glass tube and tape again tightly (see pictures 1-4 above).
Taking the sample:
Try to avoid inhaling the exhaust gases or burning yourself on the exhaust pipe!
You can usually take the sample by removing the stopper, wrapping the end of
the glass tube with a piece of cloth, removing all air inside the bag and placing
the glass tube tightly at the end of the exhaust pipe (see picture no. 5). Flush
the bag once with exhaust gas before taking the actual sample. As soon as the
picture 5
bag is filled with gas for a second time attach the closed stopper to the glass
tube (see picture no. 4). Take samples from different engine types, as soon as the engine is switched on
and once the engine has reached its operating temperature.
T1
Make a sample collection bag for each sample you plan to take.
T2
Take your samples, number each of them and find out what type of engine you have taken your
exhaust gas sample from. Analyse the samples the same day you collect them.
Table 1
petrol
engine
without catalytic converter
cold engine
engine at operating
temperature
cold engine
with catalytic converter
engine at operating
temperature
4 stroke
2 stroke
diesel
engine
4 stroke
2 stroke
© 2004 ESPERE-ENC / Seesing, Tausch, Universität-Duisburg-Essen; Duisburg
Worksheet
No.____b
Urban climate
class
air pollutants
name
date
Air contaminants from exhaust gases of motor vehicles
2. Qualitative analysis of exhaust gas (CO, CO 2 und NOx)
T3
Read the information below and write down the missing reaction schemes!
1. Identification of carbon monoxide with an ammoniac solution of silver nitrate:
Properties of carbon monoxide: solubility in water 0.23g L-1 (20 °C), boiling point: -191 °C, reducing
agent, highly toxic in concentrations w>5%
Reaction scheme for this identification:
2. Identification of carbon dioxide with lime water (aqueous solution of calcium hydroxide):
Properties of carbon dioxide: solubility in water 1.78g L-1 (20°C), sublimes: -79 °C
Reaction scheme for this identification:
3. Identification of nitrogen oxides with Saltzmann solution:
Properties of nitrogen dioxide: reacts with water yielding HNO 2 and HNO3, boiling point: 21°C, vapour
pressure: 1013 hPa at 20 °C, highly toxic in concentrations w>1%
Reaction scheme for this identification:
Exhaust gases contain substances that are hazardous to your health:
Use a fume hood or work outside !
T4
T5
Plan an experimental set-up and a procedure which meets the following criteria:
1. Each exhaust gas sample should be simultanuously tested for carbon monoxide, carbon dioxide
and nitrogen oxides.
2. The identification should be arranged in the order in which they do not falsify of interfere with
each other. (Take into consideration the different solubilities, reactivities with water and
reaction products.)
3. A semi-quanitative differentiation of the concentration of the pollutants in the different exhaust
gas samples should be made by controlling the volume of the tested exhaust gases.
Analyse your exhaust gas samples and list your results in the table below.
sample no.
CO
CO2
NOx as NO
© 2004 ESPERE-ENC / Seesing, Tausch, Universität-Duisburg-Essen; Duisburg