1) does an increase in temperature increase the rate of bothe exothermic and endothermic reactions?
2) is the reaction between sodium thiosulphate and hydrochloric acid self-sustaining?
This is for a practical investigation and im battling to find answers..any help greatly appreciated :)
http://answers.yahoo.com/question/index?qid=20070928121722AA5hoak
On the second question, I do not know what you mean by self-sustaining.
1. Yes
2. Yes
1) To determine whether an increase in temperature increases the rate of both exothermic and endothermic reactions, you can refer to the principles of chemical kinetics. The rate of a reaction generally increases with an increase in temperature, regardless of whether it is exothermic or endothermic.
As the temperature rises, the average kinetic energy of the reacting particles increases. This leads to more frequent and energetic collisions between the particles, which in turn leads to a higher probability of successful collisions and thus a faster reaction rate. Therefore, an increase in temperature usually accelerates both types of reactions.
However, it is important to note that the extent to which temperature affects the rate of a reaction depends on various factors, including the activation energy and the specific reaction mechanism. These factors can differ for different reactions.
2) To determine whether the reaction between sodium thiosulphate and hydrochloric acid is self-sustaining, you need to consider what "self-sustaining" means in the context of chemical reactions.
A self-sustaining reaction is one that continues without the need for any external input of energy once it has started. In other words, it is driven by energy released during the reaction itself.
The reaction between sodium thiosulphate and hydrochloric acid does not possess this self-sustaining characteristic. It is an example of an exothermic reaction, meaning it releases energy in the form of heat. However, the reaction requires an initial input of energy (such as the addition of heat or by mixing the reactants) to start.
During the reaction, a precipitate of sulfur is formed, which progressively makes the solution cloudy. This cloudiness can be used as an indicator to measure the rate of the reaction, as it relates to the amount of time required for the solution to become completely opaque.
Therefore, the reaction between sodium thiosulphate and hydrochloric acid is not self-sustaining. It requires an initial input of energy to commence, and once the reaction has exhausted the available reactants or conditions change, it will stop.
For your practical investigation, you can investigate the effect of temperature on the rate of this reaction by measuring the time it takes for the solution to turn fully opaque at different temperatures. You can vary the temperature by using a water bath or a heating source. Remember to use appropriate safety precautions when handling chemicals and heat.