1. Balancing Equations Conservation of mass

2. - Describing Chemical Reactions What Are Chemical Equations? chemical formulas and other symbols instead of words to summarize a reaction. Reactants: substances that begin a reaction Products: substances formed in a reaction

3. - Describing Chemical Reactions Conservation of Mass in a chemical reaction, the total mass of the reactants must equal the total mass of the products

4. - Describing Chemical Reactions Balancing Chemical Equations a chemical equation must show the same number of each type of atom on both sides of the equation.

5. Examples HCl + Zn → ZnCl 2 + H 2 –Are the same numbers of atoms on both sides? –Which side has less of an element? 2HCl + Zn → ZnCl 2 + H 2

6. Balancing Equations Activity Go to my website: http://admin.bhbl.neric.org/~klong to practice equations. http://admin.bhbl.neric.org/~klong - Describing Chemical Reactions

7. - Controlling Chemical Reactions Energy and Reactions All chemical reactions need a certain amount of activation energy to get things started.

8. - Controlling Chemical Reactions Rates of Chemical Reactions The cells in your body (as in all living things) contain biological catalysts called enzymes. At the end of a reaction, an enzyme molecule is unchanged.

9. What increases reaction rate? (how fast a reaction will happen) Increased rate of reaction Increase in surface area Increase in temperature Increase in concentration of reactants (NOT add more of the chemical!!!!) Use of a catalystcatalyst Causes Effect - Controlling Chemical Reactions Law of conservation of mass with Brainpop