Laboratory Preparation of Hydrochloric Acid

Laboratory Preparation of Nitric Acid

Laboratory Preparation of Hydrogen

Read the commentaries to the lab experiment and then comment the formulas below.

The most convenient laboratory method for the preparation of hydrogen is based on the reaction of zinc with dilute sulphuric acid. The gas is to be collected over water. Zinc’s rate of reaction can be easily controlled by regulating the rate with which sulphuric acid is added.

Zn+H₂SO₄ H₂+ZnSO₄

The surface of pure zinc placed in a solution of dilute sulphuric acid becomes coated with a film of hydrogen, the reaction proceeds very slowly. The evolution of gaseous hydrogen cannot be observed.

Nitric acid may be prepared by the reaction of concentrated sulphuric acid with sodium nitrate. In the laboratory method, a mixture of sodium nitrate and concentrated sulphuric acid is heated in a glass retort. Nitric acid is boiled out of the mixture and is condensed:

NaNO₃+H₂SO₄ = HNO₃+NaHSO₄

Many experiments can be carried out in the laboratory of inorganic chemistry. Thus, if we want to obtain hydrogen chloride (HC1), which is often referred to as a hydrochloric acid gas, it is necessary to pour some sulphuric acid through a tube over the crystals of sodium chloride in flask. The flask is to be heated. On warming the flask, the hydrogen chloride is expelled as colourless gas with a suffoсating odour.

It produces heavy clouds white fumes when it comes in contact with the moist air of the room. It is soluble and it cannot be collected over water as are oxygen and hydrogen. It is much heavier than the air and may be passed through a glass tube to the bottom of a bottle.

Ca(OH)₂ + 2NH₄Cl = CaCl₂ + 2NH₃ +2H₂O

CH₃CH₂OH ^H2SO4Br2 CH₂ = CH₂ () + H₂O

Cu (OH)₂ = CuO () + H₂O

4P + 5O₂ = 2P₂O₅

17. Answer the questions:

1. What is the laboratory method for the preparation of hydrogen based on?

2. Where is gas to be collected?

3. How can the zinc's rate of reaction be controlled?

4. Can the evolution of gaseous hydrogen be observed?

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