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9 Cards in this Set
- Front
- Back
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give an example of a slow reaction
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iron rusting
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give an example of a medium reaction
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metal (magnesium) reacting with acid (stream of bubbles.)
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give an example of a fast reaction
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explosion (over in a fraction of a second
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give four factors that affect the speed of a reaction
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temperature
concentration catalyst size of particles |
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explane collision theory
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Reaction rates are explained perfectly by collision theory. Its really simple, it just says that the rate of reaction simply depends on how often and how hard the reacting particles collide with each other the basic idea is that particles have to collide in order to react, and they have to collide hard enough (with enough energy.) sometimes called activation energy
More collisions increases the rate of reaction all four methods of increasing the rate of reactions can be explained in terms of increasing the number of successful collisions |
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how does increasing the temperature make the particles move faster
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when the temperature is increased the particles all move quicker therefore they are going to have more collision. The higher temperature also increases the energy of the collisions (harder collisions)
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give two ways to increase the rate of reaction and explain them
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Temperature two reasons why higher temperatures speeds up reaction are more frequent and harder collisions. Often a rise of just ten degrees of temperature will double the rate of reaction.
Concentration- in a more concentrated solution, the particles of the dissolved substance are closer together this means that when another substance is added collisions will take place more often |
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how does increasing the surface area increase the rate of reaction
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the smaller the pieces a solid is made into, the greater its surfave area and so the faster it reacts for example, indigestion tablets work faster if they are chewed rather than just swallowed. Chewing breaks them up into smaller pieces, increasing their suface area
for example, if a cube is cut in half, there are two extra surfaces so there is a larger surface area. The more pieces a solid is broken up into, the more suface area it has and so more of its particles can be hit by the other reactant. This means the reaction is faster and explains why a powder reacts faster than lumps of a solid. |
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what does a catalyst do
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Catalysts are substances that change the rate of reactions without being used up. Most catalysts speed up reactions and work by lowering the activation energy. Catalysts that slow reactions down are called inhibitors. They work by increasing the activation energy
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