CATALYSTS: A catalyst is a substance which increases the speed of a reaction, without actually being changed or used in the reaction. Catalysts make reactions easier to happen by lowering the activation energy, so low temperatures can be used. Different reactions use different catalysts. One type of catalyst which is found in living cells, is called enzymes also known as biological catalysts. Biological catalysts are used in our bodies to help big reactions take place, such as digestion of our food. Catalysts are used in the industry immensely, as they save time and money, y speeding up reactions that could take forever.
We are looking at the decomposition of our reactant-hydrogen peroxide, the equation for this decomposition is:
2H202 2H20 + 02
This reaction is fairly slow, but if u add a catalyst such as blood or potato skin, it should speed up the reaction, if you wanted to measure the rate of reaction, of this reaction, a good way would be to measure the amount of oxygen given off in the reation.
Catalyse is an enzyme. It has four polypeptide chains that are each composed of more than 500 amino acids. A function of this catalyse is to prevent the gathering of hydrogen peroxide, formed as a by product of metabolic processes. Oxidation reactions which occur in living cells involve the use of catalyse.
FACTORS THAT AFFECT THE RATE OF REACTION: Reactions happen, no matter what. Chemicals are always combining or breaking down. Over and over again but not always at the same speed. There are a few things which really affect the speed of the reaction and the number of collisions that can occur:
CONCENTRATION: If there is more of a substance in a solution, there is a higher chance that molecules will collide into the substance, causing the speed of the reaction to increase. If there is less of a substance in a solution then there will be fewer collisions and the rate of reaction will happen at a slower speed, decreasing the rate of reaction.
Less substance, decreases More substance, increases the rate of collisions.
Rate of collision.
TEMPERATURE: When liquids are heated, the particles gain kinetic energy and move faster. The increased speed increases the chance of collisions between reactant molecules and the rate increases. But this is not the main reason because when heated molecules have a greater kinetic energy, the greater proportion of them have the required energy to react. The increased chance of the fruitful energy collisions greatly increase the speed of reaction. The higher the temperature the faster the rate of reaction, and the lower the temperature the slower the reaction.
Cold solutions- not very Hot solution- More frequent collisions
frequent collisions because because particles move more quickly.
Solute particles move slowly
PRESSURE: Pressure effects the rate of reaction especially when you look at gases. When you increase the pressure the molecules have less space to move around. That greater concentration makes them collide with each other more often. When you decrease the pressure molecules don't hit each other as much and there are fewer collisions. That lower pressure lowers the rate of reaction.
SURFACE ARE: Catalysts are usually used as a powder or pellets. This gives them maximum surface area to enable the reacting particles to meet up and react. So the larger the surface area, in my experiment, the more the frequency of the particles colliding with more energy. The smaller the surface area, in my investigation the less frequency of the particles colliding with less energy.
More surface area for the Less surface area for the particles
Particles to collide to collide.
• CATALYSTS: Catalysts are substances that make reactions take place
More quickly, but catalysts are not used up in the process of catalysis. Any reaction in which a catalyst has been used is called a catalysis. The amount of catalysts added into the solution does not effect the rate of the reaction. Chemical changes carried out in living cells use biological catalysts called enzymes. Many industries rely on catalysts to speed up their reactions, such as the production of cheese, enzymes are used to make the production of cheese quicker.
STIRRNG: When you stir the reactant particles, the particles are able to move and this would increase the frequency of them reacting together. Therefore there are more collisions and an increase in the rate of reaction.
LIGHT: This factor only effects a few reactions such as photosynthesis.
MY CHOSEN FACTOR: My chosen factor is concentration and I will conduct my experiment around this factor.
HYPOTHESIS: I think that the more concentration there is, the oxygen will be produced, and the more dilute the mixture the less oxygen will be produced. This is because more H202 there is, the more solute particles there are to collide into. As the concentration becomes more dilute, the reaction becomes slower. I think that therefore my graph will look like this:
My graph will have a straight line going through the origin, and the rate of reaction will increase proportionally to the concentration.
APPARATUS:
• Hydrogen Peroxide-this is my reactant I am going to use.
• Potato-this is my biological catalyst (2g/5g)
• Trough-this is to put my water in
• Measuring cylinder- to measure the amount of hydrogen peroxide and water
• Spatula-to take out my hydrogen peroxide
• Delivery tube-this is what my oxygen will travel through from the conical flask to the eudiometer.
• Conical flask-I am goin to put my solution into this
• Burette-I am going to measure the amount of hydrogen peroxide
• Stop watch- to time my reaction 2 minutes.
• Rubber cork-this is to prevent my oxygen from escaping.
• Eudiometer-to collect oxygen
METHOD: First I measured hydrogen peroxide and water using a burette. I then filled a trough with water along with a eudiometer. I then put the measured amount of hydrogen peroxide and water together into a conical flask, adding my 5g of potato, Closing the flask with a rubber cork to make sure any oxygen doesn’t escape. I then quickly started the stopwatch and waited for the oxygen to collect in the eudiometer for 2 minutes. I recorded the time taken for the oxygen to be collected. I done the same thing 5 times each time making the hydrogen peroxide 20% more dilute and reducing the amount of water by 20%. I used the same catalyst each time.
MY PRELIMINARY: I decided to do a preliminary test. Which is basically a rough test to see if my investigation will work. I decided to use two different amounts of potatoes too see which would give me more accurate results.
After looking at the results I have decided to use only 5g of potatoes for my final experiment because I feel that there is a better rage of results there.
MY FINAL EXPERIMENT:
METHOD: My method will remain the same as stated above the only change is that I am only using 5g of potatoes.
SAFETY: I am using glass equipment so I have to be careful and make sure I don’t drop nothing. I also have to use safety goggles because I am using chemicals and if these chemicals get into my eyes they could cause irritation. I also have to make sure that any hazards such as bags n things are out of the way before conducting my experiment jus in case I trip over it and spill chemicals.
FAIR TEST: Everything in my experiment will remain the same such as the time, the only thing I will be changing is the concentration each time.
RESULTS:
To work out the average amount of oxygen collected, all I have to do is add the two amounts of oxygen collected for each amount of concentration, and then divide it by the number of numbers, in my case that’s 2.
