Examples of alkalis
- Sodium hydroxide - NaOH
-
Calcium hydroxide - Ca(OH)2
- Potassium hydroxide - KOH
Neutralisation
When an alkali is added to an acid, the pH of the mixture rises as the alkali reacts with it forming neutral products. An acid added to an alkali causes the pH to fall because the alkali is removed by reaction with the acid.
A reaction in which acidity or alkalinity is removed is called neutralisation. A neutralisation involving an acid and a base (or alkali) always produces salt and water (and nothing else).
Acid + base → salt + water
The factor that could change my investigation is the concentration of the acid that I use as according to the collision theory, as the concentration of the acid increases so does the rate of reaction due to more successful collisions between the particles and so as a result, this leads to more heat being let off.
Another possible factor that could have an effect is the surface area of my reactants. The larger the surface area, the quicker the reaction is as more particles are exposed and so can react. This therefore too can affect the heat of neutralisation.
Temperature could also affect the experiment as typically a 10 degrees Celsius rise in temperature can roughly double the rate of many reactions, thus increasing the heat of neutralisation. This will defiantly affect an exothermic or endothermic
reaction.
Concentration - If the solution is made more concentrated it means it
contains more particles of reactant, therefore more collisions are
likely and an result of this is that the temperature will decrease
because bonds are being made.
Adding a catalyst could also have an effect as there are chemicals that can speed up a chemical reaction without affecting the process and this as a result would lead to a greater transfer of energy.
These are the factors that will affect a . A
neutralisation is either exothermic or endothermic. Exothermic
reactions are the reactions that give out energy and therefore the
temperature rises as a result of this. Endothermic reactions are the
ones that take in energy from the surrounding and cause the
temperature to decrease as a result of this.
My hypothesis is going to be to investigate how energy is transferred from the reactants to the product and if any of it is released as heat energy. In this investigation my aim is to examine the temperature in a neutralisation reaction, this will vary depending on the volume of acid and alkali used. Specifically the change from the start temperature of the acid and the alkali to the finish of the neutral solution. The way in which my hypothesis will affect my investigation, is that the more volume of acid there is the, higher the rate of reaction will be; thus the greater change in temperature. By using the collision theory The more collisions that can occur simultaneously, the more the rate of reaction will increase, thus also increasing the rate of the volume of acid.