Rates of Reaction

Rates of Reaction

• The rate of reaction is how fast the reactants are changed into products.
• One of the slowest is the rusting of iron.
• Other slow reactions include chemical weathering, like acid rain damage to limestone buildings.
• An example of a moderate speed reaction is the reaction of metal magnesium with an acid to produce a gentle stream of bubbles.
• Burning is a fast reactions, but explosions are even faster and release a lot of gas. Explosive reactions are all over in a matter of seconds.
• You can find the speed of a reaction by recording the amount of product formed, or the amount of reactant used up over time.
• The steeper the line on a reaction graph, the faster the rate of reaction. Over time, the line becomes less steep as the reactants are used up.
• The quickest reactions have the steepest lines and become flat in the least time.
• Reaction rates are explained by the collision theory. The rate of a chemical reaction depends on: 
• The colllision frequency of the reactant particles (how often they collide). The more collisions there are, the faster the reaction is.
• The energy transferred during a collision. Particles have to collide with enough energy for it to be successful.
• The minimum amount of energy needed to react is called the activation energy. Particles need this much energy to break the bonds in the reactants and start the reaction.
• Factors that increase the number of collisions (so that a greater proportion of particles collide) or the amount of energy particles collide with will increase the rate of the reaction.
• The rate of reaction depends on 4 things: temperature, surface area, concentration of a solution/ pressure of a gas, and the presence of a catalyst.
• Increasing the temperature increases the rate of reaction because when temperature is increased, particle move faster as they have highere nergy due to being heated. If they're moving faster, they're going to collide more frequently, and also the faster they move, the more energy they have and so more collisions reach the activation energy.
• More collisions means a faster rate, so increasing temperature increases the number of collisions.
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