Name: Reactions of Metal Carbonates with Acids
Uploaded: 2019-07-19
Duration: 4 min 6 s
Description: When substances like metals and liquids like acid react, it produces salt, water, and carbon dioxide. Here, in this video, it has been explained in detail wi...

Question

A group of students measured the pH of some substances they found in their homes. Their results are given in the following table:

Substance	pH	Substance	pH
Apples	3.0	Salt	7.0
Baking soda	8.5	Sugar	7.0
Black coffee	5.0	Toothpaste	9.0
Household ammonia	12.0	Vinegar	3.0
Lemon juice	2.5	Washing soda	11.5
Milk	6.5

(a) What would the students have used to measure the pH?
(b) Which solution is the most acidic?
(c) Which solution is the most alkaline?
(d) Which solutions are neutral?
(e) Which solution can be used to treat wasp stings?
(f) Which solution can be used to treat bee stings?

Accepted Answer

(a) Students have used universal indicator paper to measure the pH of substances because universal indicator tells us the strength of an acid and base.

(b) $pH \propto \frac{1}{{[H}^{+}]} \propto \frac{1}{acidic character}$ : pH of lemon juice is 2.5, it contains more concentration of hydrogen ions in it. Hence, it is more acidic.

(c) $pH \propto [{OH}^{-}] \propto basic strength$ : pH of household ammonia is 12. It contains more concentration of hydroxide ions in it. Hence, it is most alkaline.

(d) If a solution is having pH 7, then it is said to be a neutral solution because it contains an equal amount of hydrogen ions and hydroxide ions in the solution. Salt and sugar with pH = 7 are neutral.

(e) Wasp stings inject an alkaline solution into the skin which causes irritation. Effect of this alkaline solution can be cancelled by rubbing the injected area with vinegar.

(f) Bee stings inject methanoic acid into the skin. So baking soda (mild base) can be used for treatment because this base cancels the effect of acid and gives relief.

Important Questions on Acids, Bases And Salts

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