Heating the particles increases their energy and so they move about more quickly. This means there is a greater chance of collisions and the rate of reaction increases. Reactions need energy to start them off.
This energy is needed to break existing chemical bonds inside the molecules. Activation energy can be supplied in the form of heat.
As already stated, heat increases the rate of most chemical reactions. Increasing the temperature of an enzyme-controlled reaction brings about an increase in the rate of reaction, but only up to a point. Increased kinetic energy of both the substrate and the enzyme molecules is brought about by increasing the temperature to about 40o C. This in effect means the effect of temperature T on the rate of reaction can be expressed by the temperature coefficient Q10:
Q10 = rate of reaction at T + 10oC
Rate of reaction at T
The rate of reaction doubles for each 10oC rise in temperature, but this does not go on indefinitely. The rate of enzyme-catalysed reactions reaches a peak at a particular temperature. This is the optimum temperature for the reaction. Any increase in temperature also causes the atoms making up the enzyme molecule to vibrate more. Eventually this vibrating causes the breaking of the hydrogen bonds and other bonds that hold the enzyme molecule in its tertiary structure, with its specific shape. Its three-dimensional shape alters, including the active site, which will no longer fit the substrate molecule. The enzyme is Denatured. This is a permanent change that cannot be reversed by cooling.
Addressing the issue of the shortcomings of this experiment, it could be said that at what point is denaturing irreversible? Just prior to this point, is it reversible? In order to investigate this further it could be said that the experimental reactants should be maintained at the given temperature throughout the experiment to ensure any potentially reversible denaturation is maintained throughout the course of the experiment. Another point to look at, are the temperature differentials close enough to formulate a cohesive graph. Graphs must be drawn with a line of best fit. Q10 as an equation goes up in 10oC multiples however the experiment goes up in 15, 20 and 40oC increases. It is therefore safe to suggest the experiment needs to be more controlled with more emphasis around the optimum temperature.
Table of Rate and Temperature of Reaction
Conclusion
Interpreting the information from the above table and the attached graph, it could be said that the higher the temperature the longer the reaction takes to complete as an increase in temperature will slow the reaction down. This is due to changes in the enzyme Active Site and as temperature is increased, this will eventually lead to denaturing. This can be explained by taking the example of the reaction leading up to 85o C. The rate of reaction slows down due to the Carbon, Hydrogen, Oxygen and Nitrogen atoms vibrating furiously due to increased heat equals increased kinetic (movement) energy which leads to the Active Site not maintaining its integrity and consistency and after time not holding its shape. While it can still catalyse, the reaction is not efficient. When the temperature increases to 85o C the active site has been destroyed hence the reaction ceases i.e. the albumen in eggs is runny when the egg is cold however after being boiled the albumen become hard and white. This is a classic example of denaturing.
