PHYSICAL AND CHEMICAL CHANGES

PHYSICAL AND CHEMICAL CHANGES Matter can change both physically and chemically. Law of conservation of matter: whatever kind of change happens to matter– the total amount of matter present will remain the same.

PHYSICAL CHANGES OF MATTER

PHYSICAL CHANGE Any change in state, shape, size, in which the identity of the substance does not change. A ball of clay even after changing its shape will still be clay. An ice cube melting from solid to liquid.

PHYSICAL CHANGE Solubility: The process by which a solid, liquid, or gas forms a solution in a solvent. Solvent is what another substance is dissolved in. Solute is the substance being dissolved.

PHYSICAL CHANGE Changing States of matter: the identity of the substance does not change.

PHYSICAL CHANGE Melting: When solid changes to liquid. When ice melts it changes its state to water.

PHYSICAL CHANGE Freezing: Occurs upon cooling. A substance changes its state from liquid to solid. Freezing temperature varies from one substance to another.

PHYSICAL CHANGE Vaporization is the change of matter from liquid to gaseous state. There are two types: 1- Evaporation: Occurs on the surface of the liquid only. Is an essential part of the water cycle. Water, even at room temperature, evaporates without anyone noticing it.

PHYSICAL CHANGE Vaporization: Another type is-- 2- Boiling: Occurs on the entire mass of the liquid. Boiling point of various substances varies from one substance to another. Example: water boils at 100 ° C.

PHYSICAL CHANGE Condensation: Is the opposite of evaporation. Change from gaseous to liquid form. Occurs when vapor is cooled Morning dew is an example of condensation.

PHYSICAL CHANGE Sublimation: Change of state directly from solid to gaseous form. Iodine sublimates upon heating.

PHYSICAL CHANGE Deposition: Settling of particles from a solution. Opposite of dissolution.

EXAMPLES OF PHYSICAL CHANGES

TEARING OF A PIECE OF PAPER

MELTING CHOCOLATE

CRACKING AN EGG

CHOPPING A PIECE OF WOOD

MIXING A CAKE BATTER

MELTING CANDLE WAX

MIXING WATER AND ACID

MAKING A SOLUTION OF SALT AND WATER

THE REASON FOR CHEMICAL CHANGES CHEMICAL REACTION THE REASON FOR CHEMICAL CHANGES

CHEMICAL REACTION A Chemical Change is a process in which substances undergo chemical reaction. A completely new substance forms and it is irreversible.

SIGNS OF CHEMICAL CHANGE

CHEMICAL CHANGE Production of Gas: bubbles are formed within a liquid during a chemical reaction if gas is released. Example: When vinegar is added to baking soda bubbles are formed showing that carbon dioxide is released. + =

CHEMICAL CHANGE Formation of Precipitate: A precipitate is a solid formed during a chemical reaction in a solution. New substance is insoluble and settles at the bottom. Example: Silver Nitrate & Sodium chloride solutions react together, precipitate of silver chloride settles at the bottom of The clear solution.

CHEMICAL CHANGE Color change: The new substance formed may reflect different colors of light.

CHEMICAL CHANGE Change in temperature: Either heat is released (exothermic reaction) and the container may feel hotter OR Heat is absorbed (endothermic reaction) and the container may feel colder.

CHEMICAL CHANGE Emission of Light: Light is give out as result of a chemical reaction. Example: light stick, neon lights

CHEMICAL CHANGE Smell change: Change in odor during a chemical reaction. For example: Change in smell when milk goes bad.

EXAMPLES OF CHEMICAL CHANGES

BURNING OF A PAPER

BURNING OF A CANDLE

BAKING A CAKE

ADDING BAKING SODA TO VINEGAR

BURNING OF WOOD IN THE FIREPLACE

LIGHTING A MATCH STICK

LET’S CHECK OUR UNDERSTANDING OF PHYSICAL & CHEMICAL CHANGES