Rates of Reaction Mrs. Kay

Rate of reaction  The time it takes for a reaction to take place.  The time needed for a certain amount of reactants to become a certain amount of product

Factors of Rates  Concentration  Surface area  Temperature  Using catalysts

Concentration  Is the amount of substance per volume.  If there is more concentration, then there is more chance of collision.  More collisions means faster reaction rate  Picture shows 8 successful reactions

 If there is less concentration, then less likely to have collisions  Less collisions means lower reaction rate  Picture show 3 successful reactions

Surface Area  The area of an object (length x width)  Smaller bits will react faster than bigger bits  Ex: small piece of wood burn better than large logs

 The more surface area there is, the more places for collision and reactions to take place, so faster reaction rate  The less surface area there is, the less places for collisions and reactions to take place, so the lower the reaction rate

Temperature  Remember thermal energy!  If I take energy away (lower the temperature) then there will be less movement and less collisions.  Lower temperature means lower reaction rate

 If I increase the temperature, then I increase the energy and more collisions occur  More collisions means faster reaction rate

Using Catalysts  Catalysts - a substance that increases the rate of a reaction but is not itself changed by the reaction.  Ex: like adding a chemical or even by stirring the mixture!

Acids and Bases Science 10

Acid  In 1884 the Swedish chemist Svante Arrhenius defined an acid as a substance that produces hydrogen ions in solution, H + (aq).  For example, HCl (aq), hydrochloric acid is an ionic compound that dissolves in water, splitting into H + (aq) and Cl – (aq) ions.  pH less than 7  Turns red litmus red, and blue litmus red

Bases  Arrhenius also defined a base as a substance that produces hydroxide ions in solution, OH – (aq).  An example of a base is sodium hydroxide, NaOH (aq). Sodium hydroxide forms OH – ions in solution.  pH greater than 7  Turns blue litmus blue, and red litmus blue

Neutral  pH is 7  Water is a common neutral substance.