Boiling of water and churning of milk are examples of physical changes in cooking.
Formation of curd and baking are examples of chemical changes in cooking.
Further explanation:
The property is a unique feature of the substance that differentiates it from the other substances. It is classified into two types:
1. Physical properties:
The properties that are measured without altering the chemical nature of the substance are called physical properties. These are used to observe and describe matter. Texture, color, melting point, boiling point, density, solubility, polarity are examples of physical properties. These can be intensive (depending on the nature of substance) or extensive (depending on the amount of substance). density, melting point, electrical conductivity are intensive while mass, volume, weight are extensive.
2. Chemical properties:
These properties are the characteristics of substances that are observed when it undergoes a chemical reaction. These cannot be determined by just observing or touching the substances. Heat of combustion, enthalpy of combustion, toxicity, flammability are some examples of chemical properties.
Changes are of two types:
(A) Physical changes:
The process in which the physical properties of the system are affected. These changes can also be reversed by physical methods. In these kinds of changes, the molecular composition of the substance remains the same. These are reversible in nature and no new substances are formed. For example, boiling of water, chopping of wood, melting of wax are physical changes.
(B) Chemical changes:
In this change, new substances are formed by the chemical combination of the previous substances. The chemical properties of substance changes when it undergoes a chemical change. These are irreversible in nature. For example, fermentation of grapes, burning of wood, rusting of iron are chemical changes.
Cooking includes both physical as well as chemical changes. It involves cutting of raw vegetables, boiling milk, making butter out from milk, preparing rice and many other things. Out of these, some of the cooking activities are physical changes while some are chemical changes.
Physical changes in cooking:
The boiling of water is an example of physical change. This is because this conversion results in the formation of steam from water but molecular formula and structure of both remain the same.
Churning of milk is also a chemical change as it does not change the chemical composition of milk.
Chemical changes in cooking:
Formation of curd from milk is a chemical change. This is because chemical reactions occur during the conversion process. The lactic acid results in the coagulation of proteins present in milk and such process cannot be reversed so it is a chemical change.
Baking of bread, cakes and other products results in the formation of some new substances from the previous ones. Also, such changes cannot be reversed. So it is a chemical change.
Learn more:
1. Which of these is an extensive property? https://brainly.com/question/1398514
2. Which of the phase changes is an exothermic change? https://brainly.com/question/1875234
Answer details:
Grade: Senior School
Subject: Chemistry
Chapter: Physical and chemical changes
Keywords: cooking, physical, chemical, boiling of water, formation of curd, milk, lactic acid, reversed, reversible, irreversible, physical properties, chemical properties.
