Question

baking soda is used in small amount in making bread and cake. It helps to make this soft and spongy and aqua solution of baking soda turns red litmus blue. It is also used in Soda acid fire extinguisher.
Use this information to answer the following questions -:

a) How does baking soda help to make cakes and bread soft and spongy.

b) How does it helps in fire extinguishing fire.

c) It is pH value of baking soda solution lesser than or greater than 7.

Answer 1

c)  lesser

b) to help neutrilise the fire

a) by expanding the cake

Answer 2

A. Baking powder is a mixture composed of baking soda, tartaric acid and starch. It is used in making cakes, breads and other baked food items. While preparing the dough, baking powder is added to the flour. When baking powder mixes with water, then the sodium hydrogencarbonate reacts with tartaric acid to evolve carbon dioxide gas which gets trapped in the wet dough and bubbles out slowly making the cake to rise and hence 'soft and spongy'. This gas is also released when the dough is heated due to the decomposition of sodium hydrogencarbonate. The involved equations can be shown as follows:

NaHCO3 + H+ →Na+ + CO2 + H2O

B. When sodium bicarbonate (baking soda) is heated, it becomes sodium carbonate. In this process water and carbon dioxide is released. The CO2 starves the fire of O2.

C. Greater than 7