Question

A.How do acids and bases react with metals?
B.What do you observe on the surface of zinc granules if 5 ml of dilute sulphuric acid is taken in a test tube and a few pieces of zinc granules are added to it?
C.Pass the gases evolved through soap solution-why are bubbles formed in the soap solution?
D.What do you observe if a burning candle is taken near to a gases filled bubble?
E.Answer the above question for $HCl$, $HNO_3$ and carboxylic acid in place of sulphuric acid.
Are the answers the same?

Answer 1

Hint: Acids are chemical substances which are characterized by a sour taste in an aqueous medium. They have the tendency to turn blue litmus red. On the other hand, bases are chemical substances which are characterized by a bitter taste and are slippery to the touch. Some bases are soluble in water while others are not.

Complete step by step solution:
A.When a metal reacts with an acid, it generally displaces hydrogen from the acids. This leads to the evolution of hydrogen gas. The metals combine with the remaining part of acids to form salt. For example reaction of sulphuric acid with zinc. Alkalis (bases that are soluble in water) react with the metal to produce salt and hydrogen gas. For example reaction of zinc with sodium hydroxide.
B.Zinc reacts vigorously with dilute sulphuric acid. Zinc sulphate is formed along with evolution of hydrogen gas and the container becomes hot and bubbles are formed on the surface of zinc granules.
C.When hydrogen is passed through the soap solution hydrogen does not get dissolved in it and this gas tries to escape from the solution into the environment when it reaches the upper surface of the soap solution it escapes as bubbles because in the soap solution it had less space but as it entered the air it got more space to spread.
D.On passing hydrogen gas through soap solution it does not get dissolved in it and the solution easily forms bubbles containing hydrogen gas. The presence of hydrogen gas can be tested with the help of a burning splinter near the bubbles. Then the popping sound will come.
E.$HCl$, $HNO_3$ and carboxylic acid are acids so answers of the above questions will be the same.

Note: When alkali (base) reacts with metal, it produces salt and hydrogen gas. Example: Sodium hydroxide gives hydrogen gas and sodium zincate when it reacts with zinc metal. Sodium aluminate and hydrogen gas are formed when sodium hydroxide reacts with aluminium metal.