Law of Conservation of Matter

C. Gray, 2013

Standard:S8P1g. – Identify and demonstrate the Law of Conservation of Matter

What is a PURE SUBSTANCE?• a material with a specific chemical

composition.

Examples of PURE SUBSTANCES

• Au – Gold• Li – Lithium• Ne – Neon• Ca – Calcium• Hg – Mercury• H2O – Water• NaCl - Salt

What is a COMPOUND?• a thing that is made of two or more chemically

bonded materials. It can only be separated by a procedure that breaks those bonds

What is a MIXTURE?

• A mixture is anything that is made up of two or more physically mixed things. A mixture can be separated without breaking any bonds between the materials in the mixture.

• Homogeneous Mixtures - components that make up the mixture are uniformly distributed throughout the mixture. (Ex: air, blood, saturated sugar water)

• Heterogeneous mixtures - components of the mixture are not uniform or have localized regions with different properties. (Ex: Heterogeneous mixtures: rocks, oil and water, soup, pizza)

What is a CHEMICAL FORMULA?

• a way of expressing information about the proportions of atoms that make up a particular chemical compound.

How do I write a CHEMICAL FORMULA?• Subscripts – A subscript looks like this

• Subscripts are numbers used to tell you how many atoms of an element are present in the equation; for instance:• water H20 has 2 atoms of hydrogen and one of oxygen

• glucose C6H12O6 has 6 atoms of carbon, 12 of hydrogen, and 6 of oxygen

• Coefficients - The large numbers put in front of an equation, either to balance it, or simply to tell you how many molecules there are,

• in 2H2O , the first '2' is the coefficient, & means that all the atoms following it have to be multiplied by that number - so in 2H2O there are 4 atoms of H, and 2 atoms of 0

Subscript and Coefficient example:

Reactants and Products?• In a chemical reaction, substances (elements and/or

compounds) called reactants are changed into other substances (compounds and/or elements) called products. You create a new substance with chemical reactions.

Chemical Reactions

• A number of clues show that a chemical reaction has taken place, for example:– Something new is visibly produced– A gas is created– Heat is given off or taken in

• In chemical equations, an arrow is used to indicate that a chemical reaction has taken place. In general terms, a chemical reaction follows this format:

• Reactants→Products

Counting Atoms in a Chemical Reaction

• Video to demonstrate• See review worksheet• Practice

Law of Conservation of Matter/Mass• A law that states that “matter can’t be created or

destroyed in a chemical reaction.”• It means that the amount of matter going INTO the

reaction (the reactants) must be equal to the amount of matter coming OUT of the reaction (the products)

• Review activity

Chemical Reactions – click on Bill Nye