Question

The chemical equation for the reaction of baking soda (sodium bicarbonate, NaHCO₃) and vinegar (acetic acid, CH₃COOH) may be written as two steps. Fill in the missing information for the chemical equation and balance it. Also indicate what is the reaction type for each step.

Step 1: ________+ ______ --> CH₃COONa (aq) + H₂CO₃ (l)     Reaction type:

Step 2: H₂CO₃ (l) --> H₂O (l) + _________                                     Reaction type:

When the bromothymol blue (BTB) was exposed to the CO₂ gas, what color was the solution? Did the BTB indicate presence of an acid or base? Explain your answer.

Answer 1

Step 1: CH3COOH (aq. )+NaHCO3 (aq)----- --> CH3COONa (aq) + H2CO3 (l)     Reaction type: neutralization

Acetic acid reacts with sodium bicarbonate to give sodium aceate and carbonic acid

Acetic acid is a acid and sodium bicarbonate is as base. Hence the reaction between these two is called neutralization reaction

It indicates presence of Acid

Step 2: H2CO3 (l) --> H2O (l) + CO2 (g) Reaction type: Dicomposition reaction

In step 2 the formed carbonic acid H2CO3 is unstable and dicomposes in to water and Co2

b. Bromothymol blue (BTB) is a pH indicator.

This indicator shows yellow color less than pH 6 and shows blue when the pH of the solution is above 7.6.

when you add bromothymol blue to water that ill have a blue/greeen colour.

But when you bubble carbon dioxide into the water, it form an acidic solution. hence pH is reduces below 6.0, and so the indicator turns yellow.