how can you tell when a chemical reaction has occurred

• Rusting of iron in presence of moisture and oxygen.
• Burning of wood.
• Milk becoming curd.
• Formation of caramel from sugar by heating.
• Baking of cookies and cakes.
• Cooking any food.
• Acid-base reaction.
• Digestion of food.

How will you describe the changes in the properties of materials when they are exposed to temperature?

Physical conditions like temperature and pressure affect state of matter. … When thermal energy is added to a substance, its temperature increases, which can change its state from solid to liquid (melting), liquid to gas (vaporization), or solid to gas (sublimation).

What are the characteristics that you observe from each of the material before placing them in water?

The characteristic of the material before placing it in the water is of course dry because once you place it in the water it becomes wet. the correct sick of each material before placing them on water is dry because water will make them wet . when you squeeze each material the water will come out .

How can a material undergo a chemical change?

Chemical changes occur when bonds are broken and/or formed between molecules or atoms. This means that one substance with a certain set of properties (such as melting point, color, taste, etc) is turned into a different substance with different properties.

What evidence shows that reaction occurs?

A color change, formation of a precipitate or a gas, or temperature changes are the evidences of a chemical reaction.

What always happens in a chemical reaction?

During a chemical change, the composition of matter always changes. Four possible clues to chemical change include a transfer of energy, a change in color, the production of a gas, or the formation of a precipitate. During any chemical reaction, the mass of the products is always equal to the mass of the reactants.

What must happen before a chemical reaction?

In order for a chemical reaction to take place, the reactants must collide. The collision between the molecules in a chemical reaction provides the kinetic energy needed to break the necessary bonds so that new bonds can be formed.

What characteristic best describes what happen during a physical change?

A physical change involves a change in physical properties. Examples of physical properties include melting, transition to a gas, change of strength, change of durability, changes to crystal form, textural change, shape, size, color, volume and density.

What are the signs of physical and chemical change when heat is applied?

Change in Temperature. Change in Color. Noticeable Odor (after reaction has begun) Formation of a Precipitate.

What is the characteristics of physical change?

A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.

What are the characteristics of chemical reaction give an example?

Characteristics of Chemical reaction

• 1)Evolution of gas. Some chemical reactions are characterised by the evolution of gas. …
• 2)Formation of precipitate. Some chemical reactions are characterised by the formation of precipitate. …
• 3)Change in colour. …
• 4)Change in temperature. …
• 5)Change of state.

Which characteristic of chemical reactions is depicted by the reaction between a metal and an acid?

An acid will react with a metal to form a salt and hydrogen gas. The general word equation for the reaction between an acid and a metal is as follows: acid + metal → salt + hydrogen.

What is a chemical reaction explain with example?

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