Chemistry topic 5

Chemistry topic 5 

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  • Created by: jesper
  • Created on: 08-04-12 08:48

Acids and Alkalis

Acid= a substance that dissolves in water to produce hydrogen ions.

Acid is a substance which tastes sour although tasting is not recommeneded as it can be posionous. Acid often suggest a substance burns or corrodes, but many acids are quite harmless. Indeed, much of what we eat and drink contains one or more acids.

The chemical opposite of acids is a base. Bases that are soluble in water are called alkalis. Alkalis are much more harmfull them acids and therefore need to be treated with care.  Subtances that are neither acid or alkalis properties ar neutral(E.g pure water).

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Rates of reaction

Rates of reaction
Rate= change of concentration of reactant/time

The collision theory of reaction rates

  • For a reaction to take place, the particles of the reactants must collide with one another.
  • The colliding particles must have sufficient energy to react. This energy is known as activation energy. Collision that have that required activiation energy are called succesful collisions.
  • To  increase the rate of a chemical reaction, it is necessary to increase the frequency of succesful collisions. That is, more succesful collisions need to take place every second. 
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Factors that effect the rate of reaction

Factors that effect the rate of reaction

  • Concentration. Increasing the concentration of a reactant increases the number of particles of reactant given volume hence the reacion particles will collide more often. Hence, there will be more succesful collisions per second.
  • Temperature.  By increasing the temperature you increase the kinetic energy of the particles and so more collision will occur because more have the necessary activation energy. So more succesful collisions per second. This can also be done the other way around by decreasing the temperature to decrease the reation speed.
  • State of division.  This is done by increasing the surface area so that more reactions can happen at the same time.  
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Look over all chemical experiments

Look at th experiments in book pg70 and 71.

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Comments

Olive d(>w<)b

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Tasting is not recommended, hee hee hee!

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