Question

QUEST I O N S
You Know?
Question 1. why should a magnesium ribbon be cleaned before burning in air?
Question 2. write the balanced equation for the following chemical reactions.
1. Hydrogen + Chlorine--->Hydrogen chlorine
2. Barium chloride + Aluminium sulphate ---> Aluminum chloride+ Barium suphate
3. Sodium + Water ----> Sodium hydroxide + Hydrogen
Question 3. Write a balanced chemical equation with state symbols for the
following reactions.
1. Solutions of barium chloride and sodium sulphate in water react
to give insoluble barium sulphate and the solution of sodium
chloride.
2. Sodium hydroxide solution (in water) reacts with hydrochloric
acid solution (in water) to produce sodium chloride solution and
water.


plz answer in brief with steps by step
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Answer 1

Q1) Why should a Magnesium ribbon be cleaned before burning in air?

Soln: When left unused, the outer layer of Magnesium metal reacts with the atmospheric oxygen and forms Magnesium Oxide (MgO) layer which is a very stable compound thus preventing further reactions with Oxygen. It is therefore necessary to clean the ribbon by brushing it to remove the layer of MgO so that the reaction becomes feasible with the atmospheric oxygen.

 

Q2) Write a balanced equations for the following chemical reactions.

i) Hydrogen + Chloride —-> Hydrogen chloride

ii) Barium chloride + Aluminium Sulphate —-> Barium sulphate + Aluminum chloride

iii) Sodium + Water —-> Sodium hydroxide + Hydrogen

Soln:

i) H2+Cl2→2HCl

ii) 3BaCl2+Al2(SO4)3→2AlCl3+3BaSO4

iii) 2Na+2H2O→2NaOH+H2

 

Q3) Write a balanced chemical equation with state symbols for the following reactions

i) Solutions of Barium chloride and Sodium sulfate in water react to give insoluble Barium sulfate and solution of Sodium chloride.

ii) Sodium hydroxide solution in water reacts with a hydrochloric acid solution to produce Sodium chloride solution and water.

Soln:

i) BaCl2+Na2SO4→BaSO4+2NaCl

ii) NaOH+HCl→NaCl+H2O

 

Q4) A solution of a substance ‘X’ is used for whitewashing.

i) Name the substance ‘X’ and write its formula.

ii) Write the reaction of the substance ‘X’ named in (i) above with water.

Soln:

i)The substance ‘X’ which is used in whitewashing is quick lime or Calcium Oxide and its formula is CaO.

ii) CaO+H2O→Ca(OH)2

 

Q5) Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

Soln:

When an iron nail dipped in the copper sulphate solution, the iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour of the copper sulphate solution changes. The reaction is :

Fe+CuSO4—−>FeSO4+Cu

 

Answer 2

Answer:

Explanation:

Mg ribbon is rubbed with sand paper before burning so as to remove the layer of oxygen over it which is unreactive. 1. H2 + Cl2= 2 HCl. 2. BaCl2 + Al2(SO4)3= BaSO4 + AlCl3. 3. 2Na + H2O= 2NaOH. 4.Bacl2 + Na2SO4= BaSO4 + 2NaCl