Question

a) define a universal indicator. write its one use. b) solution A gives pink colour when a drop of phenolphthalein indicator is added to it. solution B gives red colour. when a drop of methyl orange is added to it. what type of solution are A and B and which one of the solution A and B will have a higher pH value. c) name one salt whose solution has pH more than 7 and one salt whose solution has pH less than 7. Name one salt who solution has PH value more than 7 advanced auto suggestion less than 7

Answer 1

it is a substit is a substance that indicates also that substance is acidic or basic by changing its own colour example turmeric paper

A)is base

B) acidic in nature the salt having pH less than 7 is

Answer 2

Answer:

(a) Universal indicator is a mixture of many different indicators which gives different colours at different pH values of the entire pH scale.

It shows different colours at different concentrations of hydrogen ions in a solution.

(b) Solution A gives pink colour when a drop of phenolphthalein indicator is added, therefore A is a base.

Solution B gives red colour when a drop of methyl orange is added to it, therefore B is an acid.

Hence, solution A will have less concentration of hydrogen ion than B.

Thus, A will have pH more than 7 because pH value of :

-an acid solution <7 ,

-a base solution >7 , and

- a neutral solution =7

(c) - The salts of strong acids and weak bases give acidic solution have pH less than 7. Example, NH4Cl, Ammonium Chloride will have pH less than 7.

-The salts of a weak , acids and strong bases give basic solution having pH more than 7. Examples, Na2CO3, Sodium Carbonate will have pH more than 7.