Question

When a bit of baking soda is added to vinegar in a test-tube, a hissing sound is heard and several bubbles occur. The test tube is closed and attached by a glass tube to another test tube containing lime water. The limewater slowly turns milky in the process. This is shown in the following experimental setup.

Which of the following cannot be considered indicators of a chemical reaction in this experiment?


(a)Occurrence of a hissing sound (b)The formation of several bubbles (c) The change in colour of liquid in tube 2 (d)The movement of gas between the test tubes​

Answer 1

Answer:

Explanation: When vinegar react with sodium bicarbonate it results in formation of sodium acetate,water & evolution of CO2 gas. This CO2 evolution is the reason for hissing sound and bubble formation.13

Answer 2

QUESTION:-

Which of the following cannot be considered indicators of a chemical reaction in this experiment?

(a)Occurrence of a hissing sound

(b)The formation of several bubbles

(c) The change in colour of liquid in tube 2

(d)The movement of gas between the test tubes

ANSWER:-

• c) The change in colour of the liquid in tube 2 is the correct option.

EXPLANATION:-

• (a)Occurrence of a hissing sound and (b)The formation of several bubbles is the wrong answer because due to effervescence that is when a carbonate or bicarbonate reacts with organic acid it gives bubbles out in effervescence which produces a hissing sound.

• The reaction between vinegar and baking soda will evolve carbon dioxide gas as an outcome of which there is a hissing sound.
• The chemical equation for the prevailing reaction is:
• NaHCO3(s) + CH3COOH(l) → CO2(g) + H2O(l) + Na+(aq) + CH3COO-(aq)

• (d)The movement of gas between the test tubes is the wrong answer because the carbon dioxide gas which is released in the reaction moves to the test tube 2 which in turn changes the lime water milky.

• Hence, c) The change in colour of the liquid in tube 2 is the correct answer.

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