Question

Cooking food is an example of chemical change. Explain.

Answer 1

Hint: To identify whether a chemical change has occurred or not look for release or absorption of heat, production of gas, some type of odour, observe colour change, sound, etc.

Complete step by step answer:
-The first step to observe chemical reaction which brings chemical change is to identify when a reaction is taking place. In chemical reaction, substances interact, and form new products. Following are the signs of a chemical reaction, and presence of more than one signs indicate that a reaction has taken place:
-Change in temperature
-Change in colour
-Odour
-Production of gas or bubbles.
-Formation of precipitate upon mixing up of liquids.
-In case of cooking, mixing the dry ingredients will not result in a chemical change, but, adding a liquid within the dry ingredients and providing heat to this mixture will bring a chemical change. In cooking of an egg, heat provided polymerizes the proteins in the egg white, and the sulphur and hydrogen in the yolk reacts to form hydrogen sulphide gas.
-Caramelization occurs which is a type of chemical reaction, when we heat sugar. Heating a meat changes its colour to brownish due to Maillard reaction.
-Baking the bread makes them rise due to the formation of carbon dioxide bubbles during the reaction between baking powder and liquid ingredients.

Note: Sometimes, it’s hard to tell if the change occurred is chemical or physical change. When sugar is dissolved in water, we observe a physical change in the form of the sugar but, chemically sugar remains the same. Melting ice is another such example.