Surface Area- Increasing the surface area of the magnesium will expose more particles to the acid therefore reducing the time it takes for the reaction to finish as it has a larger surface to attack.
Stirring-Stirring the solution will give the acid particles extra movement energy and increase their speed hitting the magnesium more and more increasing the amount of successful collisions.
Volume Of Acid- Increasing the volume of the acid would increase the amount of particles in the solution therefore increasing the chance of collisions with the magnesium. However this would be limited by the size of the magnesium.
Catalyst- Adding a catalyst to the solution sparks in itself a reaction which would give the particles in the solution more energy and increase their movement rate therefore increasing the chance of collisions between the acid and the magnesium particles.
The Word equation for this experiment
Magnesium + Hydrochloric Acid Magnesium chloride + Hydrogen
The chemical equation for this experiment is
Mg + 2HCl MgCl2 + H2
Prediction:
My prediction on this experiment is when the temperature is kept at low degrees the reaction of magnesium strips with HCl will be slower but when the temperature is raised to a higher degree the magnesium strip will react with HCl much faster.
So when the particles move faster they would have more collisions between them.
In cold temperature In hot temperature
Example when magnesium strip is set to react with HCl at 10 degrees the reaction will be much slower compared to when the magnesium strip is set to react with HCl at 60 degrees.
Preliminary Test
I have carried out preliminary test to make sure that my experiment will go right. In my preliminary test we done the same type of experiment which we will be doing for out final one. After conducting this test we found out that the test was correct and so now we could do a real experiment
Method
- I had to setup all the apparatus which were needed in the experiment
- Place some water into a bowl then add some ice to it to make the temperature to 10 degrees because we will be that is the temperature we need to start our experiment with
- Record 10ml of HCl on a test tube
- Cut out around 20 magnesium strips at one centimeter each
- Once the water is set at 10 degrees then I had o put the test tube on the beaker holding it by the clamp and stand
- Once we put in the Mg strips we have to start the stopwatch
- When the Mg strip has been fully dissolved I had to stop the stopwatch
- Check the reading on the stopwatch and record it
- After the reaction is over take out the test tube and wash it thoroughly leaving back no HCl
- Then again add 10ml of HCl on to the test tube once it becomes dry
- Repeat the same reaction 2 more time
- Then instead of 10 degrees of water we will increase it by another 10 degrees so it now will be 20 degrees
- For the same steps above I had to carry out the reaction again
- Every three times of same reaction I had to do the reaction with a higher 10 degrees of water into the bowl. The highest we will be going is 80 degrees
- I had to keep in mind that between each reaction I had to take the results and without them I would have to do the reaction again
Experiment diagram
Below is the diagram of my experiment
Results
The results below I have gained it from the experiment I have done the results shown on the table below.
To find the average number of time taken I had to use a formula which was:
Time 1 + Time 2 + Time 3
Conclusions
My predictions were correct that when the temperature increases in a rate of reaction the reaction goes much faster. You can also see this from the table of result on top that at 100 the average time is 60 seconds and when you will look at 800 the reaction took only 37 seconds
Accuracy of Results
Although there were some anomalous results in my first set of readings I think that overall the accuracy was sufficient for the experiment as the pattern shown by my results and my conclusions are supported by the collision theory.
Evaluation of the Experiment
I think that this experiment worked well, as the results fit with my hypothesis and are supported by the collision theory.
Errors
There is one suspected anomalous readings in my results from this investigation taken in the first set, for the temperature of 30ºC (see Table 1)
The anomalous readings from the first set give slower reaction rates for increased temperature which is not a trend shown by any other results in Table 1. The second set of results taken show the trend predicted in my hypothesis of increased reaction rate as temperature increases.
These anomalous readings could be due to a number of reasons as follows: -
- Errors timing the reaction length with the stopwatch - deciding when to stop the stopwatch to mark the end of the reaction was difficult as the magnesium floated to the surface causing bubbles making it hard to know when the reaction had finished.
- Variation in the shape of the magnesium ribbon - if the ribbon was twisted or misshaped it could make the hydrogen bubble effects discussed in my analysis above more significant.
- Errors in measuring the length of magnesium, longer lengths would give an increased reaction time.
- Failing to stabilize the temperature of the acid, if the temperature of the acid were higher at the bottom of the flask than at the top where the reaction is taking place this would give anomalous readings.
- Errors reading the burette - if there were less acid this could increase the reaction time.
- Temperature of the magnesium at the start of the reaction - if it had been cooler this could have slowed the initial rate of the reaction.
Improvements
We could improve our experiment in many ways such as improving the method of timing how long it takes the ribbon to dissolve by looking at the ribbon very carefully without any distraction and closely using goggles which would help us to know when exactly the ribbon got dissolve. Other improvements could be to do the experiment on a water heater except doing in the bowl because we can keep the temperature at a steady rate, which it needs to be on.
Aim:
My aim to this experiment is to discover whether different surface area affects the rates of reaction
Apparatus needed
- Electronic Balance
- Conical Flask
- Motor and Pistol
- Stopwatch
- Calcium Carbonate
- Cotton wool
- Hydrochloric Acid
Fair test
In order to keep a fair test, only the surface area (i.e. size) of the marble chips and powder is variable. Other variables are to be kept constant to avoid obtaining wrong results. These other variables include:
*Temperature: -temperature of the reactant is kept at room temperature.
*Volume of acid: - the volume of acid is kept constant at level
*Concentration of acid: - the concentration of acid is kept same throughout
*Surface area of the conical flask: - the size of the conical flask is kept same
The HCl cannot be used again after the reaction because the acid becomes less strong to react with the acid.
I need to be accurate in taking my readings as an inaccurate reading may cause errors and alter my results.
The surface area of the chips needs to be appropriate and vary in different experiments to get the correct rate of the reacting size
The word equation for this reaction is
Calcium carbonate + hydrochloric acid calcium chloride + water +carbon dioxide
The chemical equation for the reaction
CaCO3(s) + 2HCl(aq) CaCl2 (aq) + H20 (l) + CO2 (g)
Prediction (activation energy and collision theory)
I predict that as the size of particles decreases, surface area will increase causing the average collision of particles to increase. Which means that the powdered chips will react faster. An increase in rate of collision causes an equal increase in the rate of reaction. This is based on the collision theory that states that for a reaction to occur between two particles, an effective collision must take place to form product molecules. The reaction rate is the measure of how frequently effective collisions occur.
In chemical reactions, existing bonds in the reactant particles have to be broken down first before new bonds are formed to produce product particles. Reactions only occur if colliding particles have more than a minimum amount of energy. This energy is known as activation energy (EA). It acts as a sort of ‘energy barrier’ unless particles have more energy than the activation energy, the reaction cant take place.
As a result, of increase in surface area, I predict that there is greater area for contact between the powder and the acid for reactions to take place therefore increasing rate of reaction. The rate simply depends on how fast and often particles collide with each other.
The increase in surface area also results an increase in the rate of reaction. The most concentrated substances the faster that reaction would be. The more surface area will allow particles to move more freely and have more collisions
Small Surface large surface
area area
the smaller the marble chips are the increase in surface area so it also means reactions has to increase.
Safety
- Wear goggles to prevent dangerous substances (such as acid) from entering eyes as it can cause damage to the eyes.
- Handle acid product with responsibility as it is a harmful product and it is corrosive when it meets skin.
- If gas syringe is used instead of gas generator and measuring cylinder, gas syringe should be watched while collecting gas as the syringe may fall out of the end and break if too full.
- Marble chips (small or large) can be inhaled or wedged in body organs or openings E.G. ears or eyes and this is dangerous.
- Be careful pouring acid into the beaker
Method
The steps of method will show the way in which I done my experiment
- First we need the calcium carbonate into powder by using the mortal and pistol
- The powder should be measured by using the electronic balance. It should be weighed about grams
- 100 ml of acid should be added to the conical flask
- Put the flask on the electronic balance and then make the reading on the electronic to “ 0 “
- Now pour powdered form of calcium carbonate into the flask
- As soon as the reaction begins start the stopwatch
- Then immediately we kept a cotton wool on top of the flask
- Keep taking the record of the weight every minute
- Keep the reaction till 10 minutes and stop the experiment and record the final weight
- Now we had to use the chips instead for the powder of calcium carbonate
- For this reaction do the same steps above and note down the recordings
- Finally I had to put the two results on two different tables. 1 for the powder and the other for the chips
Experiment diagram
Results
We kept the reaction going on for 10 minutes each time to ensure fair test. We had different sets of results, which were
- Results for Calcium Carbonate – chips
- Results for Calcium Carbonate – powder
Calcium Carbonate – Chips
Calcium Carbonate - Powder
Analysis of results
To work out the average I added the volumes of both tries and divided them by 2. I have worked out an average because then the results will be evaluated properly and will be plotted on a graph that will give a visual comparison between the sizes of particles. From the results of my experiments I observed that each of the reactions start of fast but start to slow down after some time. A reaction is exothermic if heat energy is given out during the chemical change, and the surroundings get hotter. On the following pages there are two graphs showing the rates at different surface areas. And another graph with both the reaction compared
Conclusion
In this experiment my aim was to see which type of surface area gives the fastest rate of reaction. I have succeeded in doing so. I recorded the rates of reaction using different sizes of particles. My predictions matched and concluded with my results, as you can tell from the graph, I have proved that the smaller the size of marble chips the faster the rate because the surface area is more and more collisions take place per second. The particles of hydrochloric acid (HCl) and calcium carbonate (CaCO3) react by colliding with each other. Although the chips are the same mass with powdered chips, it has less surface area.
In the graphs, I saw distinct patterns: they all have positive link that illustrates that they all have the same trend. The graphs are more efficient in describing the same effects as that of the tables because it shows clearly that the smaller the size of particles, the faster the rate of reaction.
Evaluation
I think my experiment was successful as I was able to obtain the evidence I needed to achieve my aim. I was planning to observe each reaction for 10 minutes and was able to do so because the reactions started getting slow after a while
I had a few problems during my experiment. The size of the chips was not exactly the same, each group was made up of chips of approximately equal sizes and this is not exactly accurate. In stirring the experiment we had to be careful of stirring it evenly and not aggravating the reaction.
The experiment could have been improved in various ways. Using beads of limestone can solve the problem of unequal size of particles. Using a magnetic stirrer can be used solve the problem of uneven stirring of reactants. The use of a more accurate scale helps in solving the problem of reading off measurements from the measuring cylinder. Drawing the curves of best fit was an accurate step I took.
My graphs helped in proving my aim, A distinctive trend is shown in the graph as clearly show that small particles react faster than large particles.
I was interested in this experiment when I first started. I was interested in seeing changes in the reactants at the end of the reaction. I was very satisfied when I found out that my predictions were correct.
The effect of concentration on
Rate of Reaction
Aim
In this experiment my aim is to find out whether rate of reaction increases when concentration in a reaction is increased.
Word equation
Sodium Thiosulphate + Hydrochloric Acid Sodium Chloride +
Sulphur Oxide + Water + Sulphur
Chemical formula
Na2S203(aq) + 2HCl(aq) 2NaCl(aq) + SO2(g) + H2O(l) + S(s)
This reaction usually produces a white precipitate, which is the Sulphur and a putrid smell, which is the sodium chloride.
Two main factors are needed in this reaction for it to succeed. The first, being that the reactant particles must meet and collide. If no collisions take place then the reaction cannot happen.
Secondly the reaction must have enough energy to form a product. The activation energy is the most minimum amount of energy that is needed for a product to be formed.
Once the solution has become totally opaque the reaction is complete. This means all the reactant has been used up and the reaction is complete. We can see this if a piece of card with a cross on it is placed under the conical flask. Once the cross is completely obscured from vision, if looking through the conical flask to the bottom, the reaction has taken place. The time it takes for this to happen is measured as the rate of reaction.
Purpose of this experiment
The purpose of this experiment is to record how long it takes for the cross under the conical flask to disappear under different concentrations. We have chosen sodium thiosulphate to use in different concentrations from a range of 10 ml to 40 ml. I believe 4 concentrations will be a sufficient amount although more can be taken to further the investigation
Apparatus needed for this experiment are:
Conical Flask stopwatch White tile marked
With “ X “
Chemical needed for the experiment are:
- Sodium thiosulphate
- Water (distilled)
- Hydrochloric Acid
Fair test
I will need to keep in order to get correct results and to do this I need to keep in mind a list of variables, which are:
- The temperature of apparatus should not change
- Try to control the surface area of the reaction
- Try and judge accurately when the “ X “ mark is disappearing
- Fixed amount of Sodium thiosulphate and water should be added
Prediction
I predict that when the concentration of the acid is raised, the rate of the reaction will increase. This is because, when the concentration of acid is higher, more acid particles are present in a given volume of the solution, therefore, more acid particles are available to collide with HCl particles. This consequently increases the chances of successful collisions (those resulting in a reaction) occurring. As the collision theory states, the more collisions that occur in a period of time, the faster the rate of the reaction. This is because the reaction only occurs when Hydrochloric acid and Sodium thiosulphate particles collide each other
Safety
As safety is the number one priority in this experiment, many safety precautions were taken to make it as safe as possible
- Goggles were worn to make sure that eyes were protected.
- Hair and loose jewelry were tied up.
- A safe distant was kept in case of any spillages.
- Any spillages on clothes and skin were rinsed thoroughly immediately.
- Any spillages on work surfaces and on the floor were mopped up with a damp paper towel.
As Sulphur Dioxide can appear to be a hazardous gas, windows and doors were opened to keep maximum ventilation in the room.
Method
- 40 ml of Sodium thiosulphate should be poured in the flask
- Then 10 ml of HCl should be poured into another flask
- 10 ml of distilled water should be poured onto another flask
- Put a tile containing an X mark under the sodium thiosulphate flask
- Then mix all these 3 chemicals into one such as pour the 10 ml of water and 10 ml of HCl onto the flask containing sodium thiosulphate.
- As soon as the reaction starts put the stopwatch on
- After we saw the reaction between started forming white precipitate which made the X mark look dimmer and dimmer to finally no X mark
- As soon as the X mark is not seeable stop the stopwatch and record the time
- Everytime we finish a reaction we had to use another flask
- Everytime we start another reaction the concentration of sodium thiosulphate we decrease it by 10 ml and increase water by 10 ml
- During the experiments the amount of |Hydrochloric acid always remains the same at 10 ml
- The steps are the same for every new reaction on this experiment whether if the concentration even changes
Preliminary work
Before conducting a real experiment I will do a Preliminary test to check whether the experiment will work out. I have used the same method as shown above and theses are the results I obtained
Experiment diagram
Results
The table below shows the results of my real experiment. The experiment was done for 3 times to get the average time taken which can make it even more accurate
Conclusion
After conducting my experiment and while looking at my results I feel that my predictions were true because I predicted that when the concentration is high the reaction will be fast compared to the reaction with less concentration and same in my result I saw when sodium thiosulphate is 40 ml and water is 10ml the reaction takes 48.83 seconds but when water is at 40 ml and sodium thiosulphate is at 10 ml the reaction takes 194.00 seconds
Analysis
As you can see from the results in the section before, the graphs and recordings clearly show that the concentration does affect the rate of the reaction. As the concentration increases, the rate of reaction speeds up as well.
The following graphs clearly state that where the sodium thiosulphate was most dilute, and was at the concentration of 10ml, the rate of reaction took the longest on average and in every experiment taken. The graphs also show that the rate of reaction happened the quickest when the Na2S203 was at its highest concentration.
As you can see in the graph, the graph takes a negative correlation in form.
The rate of reaction time starts off highest because of the low concentration. As the reactant particles are further apart and there are more spectator ions present, getting in the way of the reaction. These ions do not take part in the reaction but can slow it down as the do act as an obstruction. This makes it very hard fro collisions to take place. This prevents the reaction from happening quickly and stops the product from forming quickly.
As the concentration slowly increases, the number of spectator ions decreases in the same given volume, which in the experiment is 10cm3. This makes it more likely and easier for collisions to actually occur. This being as it is, it means that the reaction happens quicker and so the products are formed quicker as well.
Even though the rates of reaction for the different concentrations were all very different, the cross on the card eventually disappeared in every experiment. The cross did not really ‘disappear’ though. This is just a phrase used. What really happened was that the solid Sulphur that is formed as a precipitate of the reactions, shields our view and it is an opaque substance. The Sulphur is a milky yellow colour and can be seen when emptying out the contents of the conical flask. It sometimes can leave a residue on the inside of the flask.
The rate of reaction also depends on how quickly all the Sulphur is formed as an end product. This can be dependent on the concentration as well. If there are more particles in a given volume there are going to be more atoms that need to bond to make the product.
Aim
My aim for this coursework is see whether rate of a chemical reaction is affected by the addition of a catalyst in the reaction
How a catalyst works
There are many ways in which we are able to speed up the rate of reactions. A catalyst can either increase or decrease the rate of reaction. A positive catalyst lowers activation energy. The particles, therefore, need less energy to react and the process proceeds more quickly. A negative catalyst (an inhibitor) slows down the rate of a chemical reaction by doing the exact opposite. However, it is important to realize that the catalyst itself does not take place in the reaction and it is, therefore, not used up in the reaction. Below is an energy diagram showing the presence of a catalyst. The graph shows the effect of a positive catalyst on the activation energy.
When you use a catalyst, there is as much catalyst at the end of the reaction as there was at the beginning. The catalyst is used over and over again. As catalysts work so fast and are used again and again, it is only necessary to have small quantities of catalyst present to make a chemical reaction go faster.
Solid catalysts work by providing a surface onto which the reactant particles can attach, react, rearrange and then leave. Catalysts work in a very similar way to increasing surface area, when it comes to the rate of reaction. Catalysts are no different. If you want a solid catalyst to be as effective as possible, it should have the largest surface area possible. By putting 'holes' in the catalyst, it will have a large surface area and be more effective at catalyzing a particular reaction than if it was just a solid lump.
Apparatus needed for the experiment
Delivery Tubes Test Tubes Test tube clamp Stop watch
Stand
Chemicals used in the experiment
- Hydrogen Peroxide
- Potato Chippings
Fair Test:
Fair test must be kept in mind to promote accurate results. For this reason I had to keep:
- The same mass for the catalyst
- The temperature during the experiment shouldn’t change
- Concentration should remain the same
Prediction
I can predict that when the catalyst will be added to the reaction the reaction will be quicker and faster because of the collision moving faster.
I predicted this because when I learnt about catalyst the fist thing that was taught to me was that catalyst increase any kind of reactions
Formula
Hydrogen Peroxide water + Oxygen
2H2O2 (aq) H20( l ) + O2 ( g )
Method
For this experiment the catalyst we will be using is Potato. And it will be cut into pieces of 1cm
The method we done our experiment is show below:
- First we need to set up all the apparatus we need during the experiment
- Put Hydrogen Peroxide inside the test tube and add Potato chippings (catalyst)
- Heat the test tube
- During the heat we will see bubbles coming out from coming out
- Once the bubbles start we need to start counting the bubbles and also start the stopwatch
- We have to keep the experiment for 10 minutes
- We have to keep recording the bubbles every minute (start counting the bubbles again from zero once a minute is over)
- After 10 minutes is over clear stop the reaction and clear all chemicals from the apparatus by washing it
- Then rearrange the apparatus
- This time we wont use the catalyst and do the same reaction
- We had to do the same steps as above
- After 10 minutes are over and we have recorded all the bubbles we will compare the two results
- After comparing the results we will find out which experiment gives the most bubbles
Experiment diagram
Results
With catalyst
Without catalyst
Conclusion
After seeing the results I have found out actually that catalyst speeds up any reaction although I predicted in my prediction but I never thought it would be a big difference in the two reactions
Evaluation
I think that my results for this experiment were correct although my three of the trials are different from each other but I made an average of the middle number between these three trials by using the formula of:
Time 1 + time 2 + time3
3
Resources