The digital stop clock Essay Example for Free

The digital stop clock Essay It is accurate because, it measures to 100ml 1. Pipette -To make sure the volume of acid used was as accurate as possible. The way we measured the acid was at eye level from the bottom of the meniscus. 1. gas syringe -To measure the volume of carbon dioxide gas produced. The syringe was precise because it measured volume in 1ml divisions. Throughout this reaction the carbon dioxide is colourless so without it I would have problems measuring and observing the reaction, so if a substance is added to give the carbon dioxide a colour, my final results might not be reliable. I have researched that using a gas syringe is a lot more efficient than using a measuring cylinder as problems occur with the air bubbles.. 1. The electronic balance We used to measure the amount of calcium carbonate we would need for each experiment. The balance is measured in grams (g) We used also used this equipment to ensure the experiment is precise because the electronic balance is measured to 3 decimal places which are helpful as I am using a mass of 0. 5grams. 1. The digital stop clock. -We used the stop clock to time how long the experiment would last for and to make sure that we didn’t go over the amount of time set to do each repeat. There is a start and reset button to start the timer and a stop button to stop the timer this makes it more easy to use. The digital stop watch is also precise because it measures to hundredth seconds which helped us accurately record the volumes of gas at our set intervals and making the experiment a fair test as every measurement was taken at certain time. 1. Stand clamp: The reason why we used this is because the stand clamp for safety reasons as we must ensure that ga syringe and the flask with the acid that are connected to each other are stable so they do not tip over, this is because it may affect the results, and if the acid spills it could be expensive to replace a new one. Same goes with the gas syringe. The reason we used a stand clamp is because the equipment were held steadily to increase the gas flow through the tubing. This will help the gas access the syringe to read the results more accurately. 1. Spatula: We used the spatula to take out the calcium carbonate from the jar because it was the only equipment small enough to fit through the jar. Using another piece of equipment, for example a spoon, would be too large to fit through. 1. Weighing Boat: We placed the calcium carbonate in the weighing boat after we measured it. The weighing boat is light, so it will not affect how we measure the calcium carbonate. 1. Goggles: We wore goggles as part of our health and safety rules that we had to follow to stop any injuries from happening. An example for when we need goggles is when we need to prevent acid from getting into your eyes as it may damage your eyes for the long term. 1. Conical flask with bung: We used this piece of equipment because we needed to put in the reactants (calcium carbonate and hydrochloric acid) that we used when measuring the amount of gas being produced. It attached onto the gas syringe so the gas that was produced in the reaction could pass through the tube to be measured. The bung is there to make sure that the gas being produced, does not escape from the conical flask. The method consists of several steps: 1. Put on your lab coat and goggles. 2. Gather all the equipment that you need e. g. gas cylinder with chronicle flask, two clamp stands, measuring boat, measuring cylinder, and stop watch. 3. Set your equipment up e. g. clamp the gas cylinder into one clamp stand, and clamp the chronicle flask into the other clamp stand, making sure they are at the same height 4. Measure the hydrochloric acid with a measuring cylinder. 5. Pour the acid into the chronicle flask 6. Weigh out the calcium carbonate with the electronic balance. 7. Pour the calcium carbonate into the chronicle flask 8. Place the bung on straight away, and start the digital stop watch 9. Take readings from the gas cylinder every 10 seconds. Main experiment – changing the surface area. The equipment we used was pipette. We used this to make sure the volume of acid used was as accurate as possible. The way we measured the acid was at eye level from the bottom of the meniscus. We used the gas syringe to measure the volume of carbon dioxide gas produced. The syringe was precise because it measured volume in 1ml divisions. We used the electronic balance to ensure the experiment is precise because the electronic balance is measured to 2 decimal places and we also used the stop clock as it is precise because it measured to hundredth seconds. This helped us accurately record the volumes of gas at our set intervals. In the surface area we made sure that we kept the 2M of the hydrochloric acid for each experiment of the surface area. We also used a mercury thermometer as it gives us a better precise reading and allows us to see whether the temperature of the hydrochloric acid makes a difference to the results. The method of the experiment of surface area was on the first experiment we used small calcium chips with the mass of 1. 5g. We measured this by using an electronic balance and we used 2M of hydrochloric acid of a volume of 30ml, by using a measuring cylinder which allowed us to measure the volume accurately. The second experiment we used medium calcium chips with the mass of 1. 5. We measured this by using an electronic balance and we used 2M of hydrochloric acid of a volume of 30ml by using a measuring cylinder which allowed us to measure the volume accurately. For the third experiment we used large calcium chips with the mass of 1. 5g. We measured this by using an electronic balance and we used 2M of hydrochloric acid of a volume of 30ml by using a measuring cylinder which allowed us to measure the volume accurately. For every experiment for the surface area we poured the hydrochloric acid into the conical flask, and then added the calcium chips as fast as possible to ensure the gas does not escape into the air, and not in the gas cylinder. As soon as we placed the bung inside the conical flask, we immediately started the stop watch and timed it up to 120 seconds. For every 10 seconds the person in role of the stop watch would shout at every 10 seconds, and the other person reading the gas cylinder will shout how fast the rubber, tubing is moving out of the gas cylinder. Then we would record the results in the table and repeat the same experiment 5 times to make the results precise and reliable. Results for surface area. We first started off with calcium carbonate powder (1. 5g)with hydrochloric acid (30ml) but the reaction took place within 5 seconds and immediately reacted. Therefore it was very fast and it was impossible for us to take any readings. Because of this we decided to use calcium carbonate chips so it is easier to take the reading. Table 4. Results for small chips of calcium carbonate Calcium Small Chips 1. 5g Hydrochloric Acid 2M 30ml Volume Of Gas Produced (ml) Time Repeat1 (ml) Repeat 2 (ml) Repeat 3 (ml) Repeat 4 (ml) Repeat5 (ml) Averages Evaluating the results for small chips of calcium carbonate Table 4 shows the surface area of small calcium chips. We did this by using 1. 5g of small calcium chips and 30ml of volume of 2M hydrochloric acid. There does not seem to be any outliers; a good start for the first results. As you can see we repeated the experiment 5 times to result precision. From the Table 4, we can see that the volume of gas produced increased fast towards the average of 110. From this we were keen to find out if the medium calcium chips made a more noticeable difference. Table 5. Evaluating results for medium chips of calcium carbonate Calcium Medium Chips 1. 5g Hydrochloric Acid 2M 30ml Volume Of Gas Produced (ml) Time Repeat1 (ml) Repeat 2 (ml) Repeat 3 (ml) Repeat 4 (ml) Repeat 5(ml) Averages   Outliers Evaluating results for medium chips of calcium carbonate. In Table 5, we show the surface area of medium calcium chips. We did this by using 1. 5g of medium calcium chips and 30ml of volume of 2M hydrochloric acid. In this graph there seems to be an outliner which is highlighted in blue. For the averages we did not include the outlier to give us a more reliable and precise average. As you can see we repeated the experiment 5 times to assure result precision. From Table 5 we can see that the volume of gas produced has gradually increased towards the time of 120 seconds. This shows that medium chips are the best results so far. To make sure we have concluded the right decision we wanted to check if large calcium chips would make a stronger difference. Table 6. Evaluating results for large chips Calcium Large Chips 1. 5g Hydrochloric Acid 2M 30ml Volume Of Gas Produced (ml) Time Repeat 1 (ml) Repeat 2 (ml) Repeat 3(ml) Repeat 4 (ml) Repeat 5 (ml) Averages Outliers Evaluating results for large chips of calcium carbonate. In Table 6 we show the surface area of large calcium chips. We did this by using 1. 5g of large calcium chips and 30ml of volume of 2M hydrochloric acid. In this graph there seems to be an outliner which is highlighted in blue. In the outlier the temperature on the hydrochloric acid was 23EC, which is an inconvenience and the rest of the results that don’t have an outlier have all got 24EC. This tells us the that the change in temperature may be a reason why there may be an outlier. For the averages we did not include the outlier to give us a more reliable and precise average. As you can see we repeated the experiment 5 times to assure precision in results. From the Table 6 we can see that the volume of gas produced has gradually increased towards the time of 120 seconds. This shows that large chips results are also reliable. Graphs for surface area. In the graph I can see that small chips used in the reaction releases more volume of gas in (ml) is better as it increases the amount of carbon dioxide produced till 100 seconds so the amount of carbon dioxide produced from 100 – 120 seconds becomes constant. The medium chips starts releasing gas at 10 seconds at a volume of 9ml. The volume of gas then increases up to 120 at a volume of 83ml. The large chips starts releasing gas at 10 seconds at a volume of 9ml and the volume of gas then increases up to 120 seconds at a volume of 85ml. Because we did not carry on timing the experiment we do not know if the rate of reaction decreases at 120 seconds and more because both large and medium chips seem to be increasing the volume of gas. As you can see from these results in the graph.large and medium chips release almost the same amount of carbon dioxide. This means that both the differences between large and medium are insignificant. as the range bars overlap. Conclusion for surface area In the surface area there was more area available for collisions to take place. If the reactant is a solid it is necessary to break it into smaller pieces to increase surface area. In the surface area results, we found out that as the mass of the calcium chips are larger; it increases the speed of the particles. The faster the particles move, the greater the number of collisions, and therefore the rate of the reaction increases. Chemical reactions take place by chance. Particles need to collide with enough velocity so that they react. As surface area is increased the particles move faster since they have more energy. This means that they are colliding more often and most of the collisions have enough velocity to cause a reaction. Since there are more collisions the chemical reaction takes place faster. Main experiment – changing concentration. The equipment we used was pipette. We used this to make sure the volume of acid used was as accurate as possible. The way we measured the acid was at eye level from the bottom of the meniscus. We used the gas syringe to measure the volume of carbon dioxide gas produced. The syringe was precise because it measured volume in 1ml divisions. We used the electronic balance to ensure the experiment is precise because the electronic balance is measured to 2 decimal places. Qe also used the stop clock as it is precise because it measured to hundredth seconds which helped us accurately record the volumes of gas at our set intervals. In the concentration we made sure that we kept the calcium carbonate small chips of 1. 5g and the hydrochloric acid 30ml but just changed the M to 0. 5M, 1M, 1. 5M, 2M for each experiment for the concentration. We also used a mercury thermometer as it gives us a more precise reading and allows us to see whether the temperature of the hydrochloric acid makes a difference in the results. The method of the experiment for the concentration was on the first experiment as we used small calcium chips with the mass of 1. 5g. We measured this by using an electronic balance and we used 0.5M of hydrochloric acid of a volume of 30ml by using a measuring cylinder which allowed us to measure the volume accurately. In the second experiment we used small calcium chips with the mass of 1. 5. We measured this by using an electronic balance and we used 1M of hydrochloric acid of a volume of 30ml by using a measuring cylinder which allowed us to measure the volume accurately. For the third experiment we used small calcium chips with the mass of 1. 5g. We measured this by using an electronic balance and we used 1. 5.