rates of reaction

• There are four factors that affect the rate of a chemical reaction: temperature, concentration, particle size, and use of a catalyst.
• For a reaction to occur, the particles that are reacting must collide with each other.
• Only some of all the collisions that take place cause a chemical change to happen.
• The greater the number of 'successful' collisions, the faster the rate of a reaction.
• If the temperature is increased, the particles have more energy and so move quicker, increasing the rate of reaction because the particles collide more often and with more energy.
• The higher the temperature, the faster the rate of a reaction will be.
• If the concentration of reactants is increased, there are more reactant particles moving together, increasing the reaction rate.
• The higher the concentration of reactants, the faster the rate of a reaction will be.
• By decreasing the particle size of a reactant, we are increasing its surface area, increasing the chance of collisions and thus the rate of reaction.
• The smaller the particle size, the faster the reaction.
• A catalyst speeds up the rate of a reaction but is not used up in the reaction, allowing the reaction to take place at a lower temperature.
• Enzymes are biological catalysts that occur naturally in the body and help with digestion.
• Enzymes are used in the production of alcohol (zymase) and digestion of food (amylase).
• Enzymes are specific, meaning they can only catalyse one reaction.
• Many enzymes work best at body temperature, but they are less effective at high temperatures.
• At high temperatures, the enzyme molecule changes shape (denatures) and no longer speeds up the reaction.
• An enzyme is a protein which catalyses or speeds up chemical reactions.
• A product is a substance formed in a chemical reaction.
• A reactant is a chemical present at the start of a reaction.
• The reaction that would produce hydrogen the fastest is 1 mol/l hydrochloric acid reacting with zinc powder.
• The reaction that would produce hydrogen the fastest is 1 mol/l hydrochloric acid reacting with a lump of zinc.
• A catalyst speeds up a reaction and is not used up in the reaction.
• A pupil monitors the rate of a reaction by measuring the volume of gas that is being produced every 15 seconds.
• The units for calculating the rate of reaction will be g s -1 when measuring in grams, cm 3 s -1 when measuring in cubic centimeters, and mol l -1 s -1 when measuring in moles.