CHEMICAL REACTIONS Chapter 3.1

Atoms interact in chemical reactions Chemical Reaction: produces new substances by changing the way in which atoms are arranged. Recall… Physical Change: changes in the state of matter, but it is still the same substance Chemical Change: original substance changes into a completely new substance; cannot be undone

Reactants vs products Reactants: The substances present at the beginning of the chemical reaction Products: The substances formed by a chemical reaction

Evidence of chemical reactions Color change Formation of a precipitate Precipitate: solid product formed when chemicals in two liquids react Formation of a Gas Temperature Change

Types of chemical reactions Synthesis: a new compound is formed by the combination of simpler reactants.

Types of chemical reactions Decomposition: a reactant breaks down into simpler products, which could be elements or other compounds.

Types of chemical reactions Combustion: One reactant is always oxygen and another reactant often contains carbon and hydrogen. The carbon and hydrogen atoms combine with oxygen, producing carbon dioxide and water.

THE RATES OF CHEMICAL REACTIONS CAN VARY CONCENTRATION MEASURES THE NUMBER OF PARTICLES PRESENT IN A CERTAIN VOLUME A HIGH CONCENTRATION MEANS THERE IS A LARGE NUMBER OF PARTICLES COLLIDING AND REACTING. HIGHER CONCENTRATION  INCREASED REACTION RATE

THE RATES OF CHEMICAL REACTIONS CAN VARY SURFACE AREA BREAKING A LARGE PIECE OF MATERIAL INTO SMALLER PIECES INCREASES THE SURFACE AREA OF THE MATERIAL. MORE SURFACES ARE EXPOSED. INCREASED SURFACE AREA  INCREASED REACTION RATE

THE RATES OF CHEMICAL REACTIONS CAN VARY TEMPERATURE AS TEMPERATURE INCREASES, PARTICLES MOVE FASTER. AS A RESULT, MORE COLLISIONS TAKE PLACE PER SECOND AND OCCUR WITH GREATER FORCE. INCREASED TEMPERATURE  INCREASED REACTION RATE

THE RATES OF CHEMICAL REACTIONS CAN VARY CATALYSTS CATALYST: SUBSTANCE THAT INCREASES THE RATE OF REACTION BUT IS NOT ITSELF CONSUMED IN THE REACTION THE CATALYST REMAINS UNCHANGED AFTER THE REACTION. IN LIVING THINGS, CATALYSTS CALLED ENZYMES ARE NECESSARY FOR LIFE.

Video: Types of Chemical Reactions Video: Rate of Chemical reactions