90 likes | 222 Vues
Balancing Equations. Conservation of mass. - 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.
E N D
Balancing Equations Conservation of mass
- 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
- Describing Chemical Reactions Conservation of Mass • in a chemical reaction, the total mass of the reactants must equal the total mass of the products
- 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.
Examples HCl + Zn → ZnCl2 + H2 Are the same numbers of atoms on both sides? Which side has less of an element? 2HCl + Zn → ZnCl2 + H2
- Describing Chemical Reactions Balancing Equations Activity Go to my website: http://admin.bhbl.neric.org/~klong to practice equations.
- Controlling Chemical Reactions Energy and Reactions • All chemical reactions need a certain amount of activation energy to get things started.
- 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.
- Controlling Chemical Reactions What increases reaction rate?(how fast a reaction will happen) Causes Increase in surface area Effect Increase in temperature Increased rate of reaction Increase in concentration of reactants (NOT add more of the chemical!!!!) Use of a catalyst Law of conservation of mass with Brainpop