Hydrogen

Question 1

Hyfrogen is the _____ and _______ element in the universe and condtitutes _______ og the universe

Answer 1

Lightes most abundant 90%

Question 2

Where is hydrogen found in the free state

Answer 2

Found in minute traces of the earths crust atmosphere and in volcanic gases

Occurs in the interior if the sun which mainlu consists hydrogen which is converted into enerfy

Question 3

Where is hydrogen found in the combined state

Answer 3

Water - about 1/9 is hydrogen
Acids
Organic compounds like protein
Plants and animal tissues are made up of hydrogen

Question 4

Process of electrolytic method

Answer 4

Electric current is passed through distilled water acidified with a few drops of dil. H2SO4

Question 5

Why is acid added to distilled water in the electrolytes methods m

Answer 5

Distilled water does not conduct electricity due to the absence of free ions. The acid helps to disassociate the water into free ions which then conducts electricity

Question 6

What are elctrodes and name the types

Answer 6

They allow electric current to enter or leave the electrolyte. They are two in nume.

• Anode - electrode connected to the positive terminal of the battery;
• Cathode - electrode connected to the negative terminal of the battery

Current enters the electrolyte - through the ‘anode’ & leaves through the ‘ cathod

Answer 7

The process of decomposition of a chemical
compound [electrolyte]
-
in the fused (molten] or solution state - by passage of an electric current
-
resulting in the dissociation of the chemical compound - into ions
-
resulting in the dissociation of the chemical compound - into ions /- which are discharged as neutral atoms - at the respective electrodes.

Question 8

What is the procedure if hydrogen preparation

Answer 8

Granulated zinc - is commercial zinc obtained from molten zind
-
It may contain traces of impurities, which have a slight catalysing effect on the reaction.
-
Traces of copper lI] sulphate added to the reaction medium - also enhances the speed of the reaction]

• Dilute hydrochloric acid - is added through the thistle Funnel ‘B’

• The preferred acia in the above preparation is - dil. HCl or dil. H2504*
• Dilute nitric acid is not used since - being a strong oxidizing agent, it would oxidise the hydrogen formed - to water.

• The reaction between zinc & dilute hydrochloric acid results in formation of - hydrogen gas.
]

Question 9

How is hydrogen collected in this case

Answer 9

COLLECTION
. The hydrogen gas formed above is collected by - downward displacement of water.
Reason: Hydrogen - is very slightly soluble in water.