Chemistry 1

• What is a Chemical Reaction?

  A chemical reaction is a process whereby chemical bonds between atoms are formed and/or broken.
• Reactants = the chemicals that react together in a reaction.
• Products = the chemicals produced in a reaction.
• Chemical reaction involves rearranging atoms to form new substances.
• Reaction rate for a chemical reaction - the quantity of reactants used or products formed overtime; how fast a reaction goes.
• The rate (speed) of a reaction can be measured in two ways:


  • Measuring the quantity formed of products over time
  • Measuring the quantity of reactants used over time
• Particle Theory states that all matter are made up of minute particles that are in constant motion and interaction with one another.
• Collision Theory - is a type of particle theory, states why different reactions occur and how they occur in different rates. It also suggests ways to change the rate of reaction.
• Concentration- by increasing the concentration, it increases the rate of reaction as it allows for more successful collisions to occur as there are more particles available to collide with.
• Pressure/Volume - when gaseous particles are under high pressure, the particles are more likely to collide as there are more molecules within a small volume. Therefore, increasing the pressure increases the reaction rate.
• Temperature - increases the reaction rate by making it more likely for collisions to occur through the increase of kinetic energy allowing more particles to move much faster. Therefore increasing the frequency of collisions.
• Agitation (stirring or shaking) - stirring or shaking a chemical reaction will increase the reaction rate as it allows particles to collide more frequently.
• Surface area - by increasing the surface area, it exposes more particles to collide with one another in the reaction, increasing the number of collisions.
• Catalysts - increases the reaction rate as it provides an alternative pathways for the reaction with lower activation energy. This factor does not get used up the reaction and particles do not need as much energy to react.
• Exothermic reactions - when the product has less energy than the reactants. This means energy has been released. (enthalpy decreases so its negative)
• Endothermic reactions - when the products has more energy than the reactants. This means energy has been absorbed (enthalpy increases so its negative)
• Activation energy is the minimum amount of energy required for a chemical reaction to occur