Acid, bases and salts(QNA)

 

Q1 What is an Acid-base indicator? Give one example.

Ans There are some special substances that have different colors in acidic and basic mediums. They are called acid base indicators. Litmus is a natural indicator obtained from Lichens.

 

Q2 Name one each of acidic and basic substances.

Ans Carbonic acid(H2CO3) is one of the acidic substances, baking soda is one of the bases.

 

Q How can carbon di oxide be prepared from an acid?

Ans The reaction of sodium carbonate with sulphuric acid is used to prepare carbon di oxide in laboratory.

 

Q4 Give two examples each of strong acids and weak acids.

Ans the two examples of strong acids are sulphuric acid(H2So4), Nitric Acid (HNO3) and two examples of weak acids are citric acid and lactic acid.

 

Q5 Why does the base applied to your skin give relief from an ant bite?

Ans When an ant stings, it injects formic acid into the skin. This irritates the skin baking soda or calamine solutions (Zinc carbonate) is used to neutralize the acid and provide relief.

 

Q6 Give two main usage each of the following.

 

a) Sulphuric acid: Automobile batteries, detergent manufacturing

b) Hydrochloric acid: Chemical manufacturing such as glue, to purify salts

c)Nitric acid: To prepare aqua Regia, to extract some metals from there ores.

 

Q7 Some acids are dangerous, others are not. Explain , giving examples.

Ans: Acids obtained from minerals are mineral acids. examples are hydrochloric acid(HCl), Sulphuric acid(H2So4),Nitric acid(HNO3), Carbonic acid(H2Co3). Most mineral acids are strong. They can cause serious skin burns.

Acids obtained from living things such as plants and animals are organic acids. Most organic acids are weak. Examples are citric acid, lactic acid, malic acid and carbonic acid etc.

  

Q8 What are bases? What are their physical properties?

Ans Substances such as baking soda that are bitter in taste and feel soapy to touch are bases. A base has chemically opposite properties as compared to an acid. Thus, a base can neutralize acid's acidity.

Q9 How can we make soap in laboratory?

Ans Take 20 ml of castor oil in beaker other oils such as coconut oil can also be used. Prepare sodium hydroxide solution (NaoH) by dissolving half a tea spoon of caustic soda in about 20 ml of water mix the oil and sodium hydroxide solution. Heat the mixture continuously and let it boil for 10 to 15 minutes continuously. The reaction that occurs

Oil + NaoH= Soap + Glycerin

To separate the soap from the soap mixture. Add a tea spoon full of salt to the beaker and stir. On cooling, solid soap separates out as a crust on the top of the solution.