Safety: during the experiment there are few things, which should be, handle with care to be safe are:
- Be careful when handling the acid that it doesn’t spill.
- Wear goggles at all times.
- Be careful when putting the marble chips in the conical flask (glass beaker) so it doesn’t break.
- Wear a lab coat, just in case the acid spills on the clothes
Prediction: I think that the powder of sodium sulphate will produce carbon dioxide quicker than the larger pieces of sodium sulphate as it will have a larger surface are for the acid to react upon.
Scientific knowledge:
The rate of reaction is how fast a reaction takes place. Increasing the rate of reaction is important in the industry because helps reduce the cost. The rate of a reaction can be measured by:
- Measuring the rate of which products are formed.
- Measuring the rate at which reactant are used up.
The collision theory: the reaction only occurs when reacting particles collide with each other and they have enough energy. The minimum energy particles must have to react is called the activation energy. If the particles collide with less energy than the activation energy, nothing will happen. Only the collisions that have energy equal to or greater than the activation energy than there will be a reaction.
The factors that affect the rate of reaction are:
- Surface area
- Temperature
- Concentration
- Catalyst or enzyme
- Pressure
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Surface area: To react, substances have to be in contact with each other. In some reactions solid is added to a solution, in these cases the size of the solid pieces make a difference to the reaction rate. The larger the surface area of the solid, the more will be in contact with the reactant and therefore the reaction will be faster.
For example: Marble chips react with dilute acid (hydrochloric acid) producing carbon dioxide and water, below is the equation:
Calcium carbonate+hydrochloric acid calcium chloride + carbon dioxide + water
Increasing the surface area increases the chance of collision taking place. For example: a reaction between magnesium metal and a dilute acid (hydrochloric acid). The reaction involves collision between magnesium and the hydrogen ions.
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Temperature: increasing the temperature increases the rate of a reaction, the reason for that is:
- The high temperature makes the particle move faster. Therefore they gain energy and they collide more often, so therefore the rate of reaction increases.
- The higher temperature means the more particles will have a higher energy; the particles will have more activation energy needed to react when a collision occur.
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Concentration: the higher the concentration of a reactant the faster the reaction. This is because according to the collision theory, increasing the concentration of reactants in a solution increases the frequency of collisions and so increases the rate of the reaction.
For example:
In the example above shows that when we have 2m of hydrochloric acid there are more particles of hydrochloric acid than diagram 2, which has 1m of hydrochloric acid. Therefore the 2m of hydrochloric acid will be faster than the 1m of hydrochloric acid because there is greater chance of collision of hydrochloric particles with the marble chip.
Enzyme or catalyst: catalyst is a substance which increase the rate of a reaction without being used up and remains unchanged therefore it can be used again and again to speed up a reaction. They can only be destroyed (inactivated) if the temperature is very high. Catalyst can also be used to slow down a reaction too. Different reactions need different types of catalysts.
In order for molecules to react they need to posses minimum energy called the activation energy. The catalyst works by lowering the activation energy required therefore more molecules have enough energy to react and the rate of reaction increases.
Pressure: Increasing the pressure in a reaction involving gases increases the rate of a reaction. Changing the pressure on a reaction that involves only solids or liquids has no effect on the rate.
Increasing the pressure of a gas is same as increasing it’s concentration. If the mass of a gas is given, then pressure can be increased by squeezing it into a smaller volume, if the mass is the same in the smaller volume, then the concentration is higher.
Result table:
Large marble chips:
Medium marble chips:
Small marble chips:
Powder:
