Preparation of Gases in Laboratory

Aims: To prepare oxygen, hydrogen and carbon dioxide gas in laboratory.

Problems :

1. How to prepare oxygen gas in laboratory?

2. How to prepare carbon dioxide gas in laboratory?

3. How to prepare hydrogen gas in laboratory?

Hypothesis:

1. Oxygen gas can be prepared in laboratory by using manganese dioxide (MnO2) and

hydrogen peroxide (H2O2).

2. Carbon dioxide gas can be prepared in laboratory by using marble chips (CaCO3) and

dilute hydrochloric acid (HCl).

3. Hydrogen gas can be prepared in laboratory by using zinc metal and diluted hydrochloric

acid (HCl).

Variables:

a) Manipulated : Materials used to produce gas

b) Fixed : Concentration of hydrogen peroxide (6% ), concentration of hydrochloric

acid (5M of HCl)

c) Responding : Gas produce (oxygen, hydrogen and carbon dioxide gas)

Operational definition:

a) Manipulated : Material that been use to produce oxygen gas is hydrogen peroxide

(H2O2), meanwhile material that been use to produce carbon dioxide are marble chips

(CaCO3) and dilute hydrochloric acid (HCl). Hydrogen gas is prepared by using zinc

metal and diluted hydrochloric acid (HCl).

b) Responding : Gases produced in this experiment were oxygen, carbon dioxide and

hydrogen gas. Reaction between manganese dioxide (MnO2) and hydrogen peroxide

(H2O2) was produce oxygen gas. Reaction between marble chips (CaCO3) and dilute

hydrochloric acid (HCl) was produce carbon dioxide gas. Meanwhile reaction between

zinc metal and diluted hydrochloric acid (HCl) was produce hydrogen gas.

Apparatus :

Round-bottomed flask, dropping funnel, gas jar, rubber tube , test tube, wooden splinter,

retort stand, glass basin, glass rod, filter funnel, measuring cylinder (500 ml and 250 ml)

and volumetric flask (500 ml).

Materials :

Hydrogen peroxide (H2O2), 6%, manganese dioxide (MnO2), hydrochloric

acid (HCl), 5M, marble chip (CaCO3), zinc metal and calsium metal.

Procedure :

Preparation of Gas in Laboratory

A) Oxygen gas

a. The volume of hydrogen peroxide is calculated to find the dilution factor from the

stock solution used.

b. Hydrogen peroxide was measured 100ml using measuring cylinder and added

distilled water until 500ml.

c. Manganese dioxide then was put into round bottom flask.

d. After that, put dropping funnel that filled with hydrogen peroxide on the round

bottom flask.

e. The rubber tube was put into the gas jar to collect the gas.

f. Then, the hydrogen peroxide was dropped on manganese dioxide.

g. The gas collected was tested with glowing splinter.

h. The observations were recorded.

i. The procedure e until i repeated to get the pure oxygen gas.

Precaution: Hydrogen peroxide (H2O2) is corrosive.

B) Carbon dioxide gas

a. Calcium carbonate (marble) chips were put into round bottom flask.

b. The dilute hydrochloric acid then titrated on marble chips.

c. The water tape was put into the gas jar to collect the gas.

d. The reaction was observed.

e. The gas collected was tested with burning splinter.

f. The observations were recorded.

g. The procedure c until g repeated to get the pure carbon dioxide gas.

C) Hydrogen gas

a. Volume of hydrochloric acid need was calculated by referring the stock solution.

b. The 500ml volumetric flask was filled up with distilled water until half of it.

c. 207 ml of the hydrochloric acid (stock solution) was measure and transfer it into

volumetric flask. This step done in fume cupboard.

d. Distilled water was added into volumetric flask until mark level.

e. The flask was shaken few time and it ready to use.

f. The dilute hydrochloric acid then titrated on zinc metal.

g. The rubber tube was put into the gas jar to collect the gas.

h. The reaction was observed.

i. The gas collected was tested with burning splinter.

j. The observations were recorded.

k. The procedure g until k repeated with using the calcium to get the pure hydrogen

gas.

Observation

Gas Reaction Observation Inference

Oxygen Hydrogen peroxide

react with manganese

dioxide

Bubble gas formed. The

glowing splinter ignited.

Oxygen gas formed

Carbon

dioxide

Dilute hydrochloric

acid react with marble

chips.

Bubble gas formed. The

burning splinter turns off the

Carbon dioxide gas

formed

light.

Hydrogen Dilute hydrochloric

acid react with zinc /

calcium metal.

Reaction between

dilute hydrochloric

acid with calcium

metal is more reactive

than using zinc metal.

Bubble gas formed. The

burning splinter giving a

‘pop’ sound.

Hydrogen gas formed

Calculation

Preparation 500ml of 6% of hydrogen peroxide, H2O2

The stock solution for hydrogen peroxide, H2O2 is 30%

Dilution factor = ratio final volume / stock solution

= 6 : 30

= 1 : 5

Determine the volume of stock solution by dividing the final volume with Dilution factor.

= 500ml / 5

= 100ml

Determine the volume of distilled water that used to dilute the stock solution.

= Final volume – Volume of stock solution

= 500 ml – 100ml

= 400ml

Thus, to prepare hydrogen peroxide, H2O2,6%, we need 100ml of hydrogen peroxide, H2O2 30%

and dilute with 400ml of distilled water.

Note: Dilution factor (DF) = ratio of final volume / aliquot volume

(final volume = aliquot + diluents) Aliquot = a measured sub-volume of original sample Diluents = material which the sample is dilute

Preparation of hydrochloric acid (HCl), 5M

The molarity for stock hydrochloric acid (HCl) = 12.08 M

The volume for 5M of hydrochloric acid (HCl) = 500ml

M1V1 = M2V2

12.08 M (V1) = 5M x 500 ml

V1 = 2500 / 12.08

= 206.95ml

≈ 207 ml

Discussion

Oxygen Gas

1. The reaction is immediate and one can observe bubbles of oxygen gas liberated in the

flask. As more hydrogen peroxide is added more oxygen gas is formed. The oxygen

produced is collected in an inverted gas jar by the downward displacement of water. The

test for oxygen gas will ignited the glowing splinter due to the presence of the oxygen

gas.

2. In this reaction, manganese dioxide acts as a catalyst. Catalyst used to accelerates the rate

of chemical reaction without itself undergoing any permanent chemical change.

3. The purity of the oxygen gas much better after first time of collection process in the gas

jar. But the purity of oxygen gas almost reaches 100% in the third time collection. The

purity of oxygen gas can be proved by observation the flame of the glowing splinter

become brighter.

Carbon Dioxide Gas

1. The reaction is immediate and one can observe bubbles of carbon dioxide gas liberated in

the flask. As more dilute hydrochloric acid is added more carbon dioxide gas is formed.

The carbon dioxide produced is collected in an inverted gas jar by the downward

displacement of water. The test for carbon dioxide gas will varnished the burning splinter

due to the presence of the carbon dioxide gas.

2. The dilute hydrochloric acid will react with marble chips to form carbon dioxide gas.

3. The purity of the carbon dioxide gas much better after first time of collection process in

the gas jar. But the purity of carbon dioxide gas almost reaches 100% in the third time

collection. The purity of carbon dioxide gas can be proved by observation the flame of

the burning splinter become vanished.

4. When the burning splinter put in test tube contain with carbon dioxide gas, the flame will

light off and when take out from the test tube, the flame will be ignited. Thus, it show

that carbon dioxide gas does not take part in combustion.

Hydrogen Gas

1. In the laboratory preparation of hydrogen, zinc is preferred, as it reacts smoothly with

either hydrochloric acid or sulphuric acid to produce hydrogen gas.

2. Besides using the zinc and acid, other methods in preparing hydrogen are like using

metals like zinc, lead and aluminium react with alkalis to yield salt and hydrogen or using

cold water by using highly electropositive metals like potassium, calcium and sodium

combine with cold water, even ice-cold water to give their respective hydroxides and

hydrogen or steam by using metals like magnesium and zinc will burn in steam, to form

their respective oxides and liberate hydrogen.

3. The purity of the hydrogen gas much better after first time of collection process in the gas

jar. But the purity of hydrogen gas almost reaches 100% in the third time collection. The

purity of hydrogen gas can be proved by comparing the sound ‘pop’ when tested with

burning splinter. The third time collection is better than the second collection.

4. The hydrogen gas is inert and light than other gaseous. When we did not hold the gas jar,

it will drop because the jar gas is filled with the hydrogen gas and it pushed the gas jar.

5. The addition of the reactant like calcium in zinc will increase the production of the

bubble gas.

Conclusion

Oxygen gas can be formed using reaction between hydrogen peroxide with manganese dioxide.

Meanwhile carbon dioxide can be produce by react dilute hydrochloric acid with marble chips

and for producing hydrogen can react between dilute hydrochloric with zinc metal. The

hypothesis was accepted.