Concentration Determines Rate of Reaction: As Explained by Collision Theory

This is because the rate of reaction is higher. This is stated in the collision theory, which says that the more the concentration the higher the rate of reaction. Apparatus  Samples of citric acid (10 g is suitable)  Calcium carbonate (see notes)  Top-pan balance for measuring quantities Range of measuring cylinders  Gas syringes  Bungs with delivery tubes  Large beakers  Syringe or pipettes, including those measuring 1 cm3  Small conical flasks Boiling tubes and test-tubes  Thermometers  Distilled water  Glass rod  Watch glass  Stopwatch or stop clock.

Candidates may also request the use of:  Top-pan balance (reading to 0. 01 g) for measuring change in mass. Controlled Variable  Same amount of citric acid being used for each reaction.  Duration of the time the carbon dioxide is measure for  The temperature of the water that is used to dilute the acid. The temperature will be room temperature  Same amount of calcium carbonate Independent Variable  The variable that I am going to change is the amount of the water that is used to dilute the citric acid Dependent Variable  The rate that the carbon dioxide that is produced by the reaction.

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Method 1. First start off by measuring 50ml of water in a measuring cylinder 2. After that pour the distilled water into a large beaker and wait for the temperature to drop/increase to room temperature, using a thermometer. We will do this by leaving the water on the table for a couple of minutes 3. Next measure the weight of the watch glass 4. Then pour some citric acid onto the watch glass and measure until you get 10g of citric acid.

To find an accurate weight we will use the top-pan balance and take away the weight of the watch glass from the end result 5.

After that pour the 10g of citric acid into the distilled water and mix thoroughly using the glass rod. This is so that the solution is diluted 6. Next, measure the 2g of calcium carbonate by using the watch glass and the top-pan balance. This is how we measured the citric acid. 7. The pour the calcium carbonate into a small conical flask 8. The pour the citric acid solution into a small conical flask 9. Immediately afterwards, insert a bung with a delivery tube into the conical flask. 10. Next insert the syringe to the end of the delivery tube 11. When the syringe is in place , start the stopwatch.

12. For every five seconds for the next thirty seconds, measure the amount of carbon dioxide that is released and record the information in a table Minimising Errors Minimising errors is reducing the amount of potential errors and mistakes during an experiment. By doing this, we can make the results of the experiment more accurate. First, we are using a pipette to get accurate volumes of water and the standard solution. This is so that all the experiments are fair. The amount of citric acid was also measured using the pipette. The amount of citric acid and calcium carbonate were kept the same.

This is, again, because we wanted to keep it a fair test. We also made sure to close the conical straight away with the rubber bung. This would prevent any carbon dioxide from escaping after the reaction had started to happen. We kept the syringe perfectly sideways and not tilted. This was so that gravity did not move the syringe around, changing the values. We made sure that the timings were recorded correctly and we used a scale with two decimal places. This gave us an accurate measure of time and how much substance we were using. Risk assessment Hazardous substance/equipment Nature of the hazard

Source of information Control measures Calcium carbonate Irritation of eyes, skin and respiratory systems, coughing Cleapss Student safety sheet Wear goggles and avoid touching eyes. Electricity Water spilling near or into electrical sockets. http://carnegiescience. edu/first_light_case/horn/labsafety. html Keep any wet material or beakers/measuring cylinders containing water away from electrical sockets. Citric acid Can cause irritation to the eyes Cleapss Student safety sheet Section 25: Citric, oxalic and tartaric acids Try to use the lowest concentration. Wear eye protection.

Diluted citric acid Discomfort to the eyes Cleapss Student safety sheet Section 25: Citric, oxalic and tartaric acids Wear goggles and avoid touching eyes. Avoid the intake (swallow) of the acid or its products. Top-pan balance Abusing the balance to give wrong readings. Not placing the sample in a container but directly on the balance. Cleapss Laboratory equipment Section 9: General Equipment Avoid dropping objects onto the balance. Samples should be weighed within a suitable container.

Glass Cuts from glass occurring when in contact with glass beakers http://www. fairbornchempage.com/Resources/Lab%20safety%20packet. htm Wear gloves while using glassware. Water Water on the floor could lead to slipping and falling.

Can fall on to the sockets, could lead to electrocution Teacher Walk carefully around the lab and avoid moving around at all. Do not put the water near sockets Table of results Test 1 Test 2 Test 3 Table of averages Analysis There are many patterns that can be found in the graph. One pattern I found is that the higher the concentration the fast carbon dioxide is produced in a certain time period. This is back up by the graph as it shows that when the concentration was 0.

231, there was 4cm3 of carbon dioxide released after 45 seconds. If we look at the amount released when the concentration was the highest, at 0. 417, the amount produced in the same time is 11. 37. This supports my hypothesis as it says that the higher the concentration the faster the rate of reaction, producing more CO2 in a certain amount of time. In addition, a pattern I found was that as time passed the rate at which carbon is produced generally slows down. We can see this in the graph as the line slowly starts becoming less steep as time passes. For example, for the 0.

417 concentration, from 0-15, it goes from 0cm3 to 6. 67cm3 whereas it only rises 1. 3 at 45-60 seconds, from 11. 33 to 12. 67. Comparing I compared my results with Tahmid Rahman’s results. The first thing I notice is that the results were very different as we used varying concentrations. However there is the general pattern that both results share, which is the higher the concentration, the faster carbon dioxide was produced and the volume of the gas. For example, in my results, if we look at the lowest concentration, 0. 231, there was 4cm3 of carbon dioxide released after 45 seconds.