Gas Syringe Essay
In this investigation I have been investigating the rate of reactions. I will be investigating the rate of reaction with calcium carbonate and hydrochloric acid, investigating the factors that affect the rate of the reaction. The rate of a reaction is how long a chemical reaction takes to happen. Some reactions are instant, like an explosion of gunpowder (KNO3) and others are slower such as the oxidation (rusting) of iron. The rate of a reaction is linked with the ‘Collision Theory’ which shows that if the rate of reaction is low, there are few collisions occurring and if the rate of reaction is high, there are many collisions.
The rate of reaction is not always the same. There are many factors which affect the rate of a reaction and these are: Concentration Temperature Surface Area Pressure Use of a Catalyst Preliminary Plan Before conducting the investigation I went through a preliminary investigation. This helped me analyse whether the method that I was using was suitable and indicated to me any changes that I might have to make while conducting my final results. To conduct the investigation I will need some a solid reactant and a liquid reactant. The solid reactant that I will be using is marble chips – calcium carbonate.
As a liquid reactant (acid) I will be using hydrochloric acid. Below I have shown a balanced chemical reaction and word equation of the reaction that I will be using to investigate the rates of reaction: CaCO3 (s) + 2HCl (aq) i?? CaCl2 (g) + CO2 (g) + H20 (l) Calcium Carbonate + Hydrochloric Acid i?? Calcium Chloride + Carbon Dioxide + Water To complete the investigation I will need an independent and dependant variable. The independent variable is the variables I will be changing throughout the investigation, which will help me, investigate the rate of a reaction.
As my independent variable I have chosen the concentration of hydrochloric acid. I will also need a dependant variable, which is the variable I will be measuring. I have chosen the amount of carbon dioxide formed as the dependant variable. To complete the investigation fairly and accurately I will need to keep the amount of calcium carbonate used, the amount of hydrochloric acid and the temperature used the same as these would be my control variables. In my investigation I had decided to investigate how the concentration of an acid affects the rate of the reaction.
To do this I have decided to use different concentrations of hydrochloric acid which range in molarity. The molarity is the number of moles of solute in one litre of solution. The range that I have decided to use is from 0. 5 moles of hydrochloric acid, to 2. 0 moles, increasing by 0. 5 moles at each test. To measure the amount of gas released after each chemical reaction I have decided to use a gas syringe, attached to a conical flask, with a bung at the end. The measurement on the gas syringe will show us how much gas has been released.
Additionally to control variables such as the amount of calcium carbonate I will be using a weighing scale and a scalpel to measure 2 grams of marble. I will also use a ruler to measure the rough size of the chip, keeping it the same to ensure a reliable test. Also to control the amount of hydrochloric acid that I will be using, I will be using a measuring cylinder to measure out 20 cm3 of acid. I will be completing in total four sets of experiments – one for 0. 5 moles, secondly 1. 0 moles, thirdly 1. 5 moles and finally 2. 0 moles.
In the experiment I will be measuring the amount of gas released over a period of two minutes at intervals of twenty seconds. For each set of experiment I will be repeating the experiment five times to ensure a reliable result. Also to control the temperature I will be completing all experiments at room temperature, to ensure that the tests are accurate. Below shows the table where I will be recording my results from the experiments. After collecting the results I will plot them of different types of graphs to analyse my data graphically. I will be analysing and writing conclusions from these graphs.
Blank Table of Results – Concentration in Moles Trail Time in Seconds Average Equipment List Conical Flask – This is where the reaction between the hydrochloric acid and calcium carbonate will take place. Rubber Bung – This will connect to the end of the conical flask and then connect to the tubing so no gas can escape. Gas Syringe – This will be connected to the end of the tubing and will be used to measure the amount of gas released from the chemical reaction.
Rubber Tubing Connection – This will be used to connect the end of the conical flask to the gas syringe. This will help make sure no gas is lost, so the results from the experiment are accurate and reliable. Stand and Clamp – This will be used to hold the gas syringe in place. Stop Watch – This will be used to help keep track of time, so at certain periods, the amount of gas released can be measured. Measuring Cylinder – This will be used to measure the amount of hydrochloric aid, to ensure that we are conducting a fair test.
Digital Scales – This will be used to control the weight of the calcium carbonate chips. Scalpel – This will be used to cut the chips to make sure they are the same weight and size. Ruler – Measure the size of the calcium carbonate chips Hydrochloric Acid and Calcium Carbonate (Marble) Chips – These are the reactants of the reaction. I will use the same amounts to ensure a fair test. (HCl = 20 cm3 at different molarities and CaCO3 = 2 grams) Diagram of Equipment Method To complete the investigation I need a clear method to tell me how to do the experiments.
Below I have written a method to show how to complete the experiments needed for the investigation: 1) Wear protective clothing such as goggles and a lab coat. 2) Collect and arrange the equipment. 3) Attach the gas syringe to the stand and clamp horizontally. 4) Attach the glass tubing to the rubber bung and the other end to the gas syringe, making sure that the syringe is push to the end, reading zero. 5) Using the measuring cylinder measure out 20 cm3 of hydrochloric acid, making sure not to spill any over skin. 6) Then place a piece of calcium carbonate of small size on to the digital scales.
Using a scalpel cut of excess amounts to make the total weight of the chip 2 grams and make all chips roughly the same size, measuring with a ruler. 7) Then add the 20 cm3 of hydrochloric acid to the conical flask, making sure the rubber bung is detached from the flask. 8) Quickly drop in the 2 grams of calcium carbonate and quickly close the conical flask by sealing it with the rubber bung. 9) At intervals of 20, 40, 60, 80, 100, 120 seconds, which can be seen from the stopwatch, note down the amount of carbon dioxide released from the reading on the gas syringe in cm3.
Note the result down in the table of results. 10) Repeat the experiment for each concentration of acid. For each concentration, repeat the experiment five times to ensure reliable results, and then calculate the average time. Safety Many safety precautions must be taken when handling with harmful substances such as hydrochloric acid. Hydrochloric acid is a particularly dangerous substance as it is corrosive to skin, meaning that it can damage eyes, skin and tissue underneath the skin. The precautions that must be taken are stated below: Wear goggles, to ensure that no acid has contact with the eye.
If acid comes in contact with the eye it can impair vision and cause blindness. Wear a lab coat to ensure that no acid is spilt over the skin. If acid comes in contact with tissue, it can cause burning and scarring. Wear gloves to ensure that no acid is spilt over the hands. If acid comes in contact with tissue, it can cause burning and scarring. Tie hair back and tuck ties into shirts to ensure that they do not affect you while conducting the practical. Complete all practical work standing, tucking chairs in, to ensure that in case acid is spilt, the person can move away quickly.
Keep the scalpel away from people and while walking hold the blade pointing towards the ground. Preliminary Results Before completing the investigation I conducted a set of preliminary results. I decided to use a solution of 2 molar hydrochloric acid as this was the highest concentration I was using and was the only molar solution available for us to use. This also meant that I could base the other concentrations depending on these results. From the results I can see that they were reliable, which shows the method that was used is accurate and produced dependable results.
Also by considering the time taken to complete an experiment for one concentration, I decided to investigate further concentrations ranging from 0. 25 molar to 2 molar, at intervals of 0. 25 molar. This helped to make the overall reliability and conclusion of the investigation accurate. Concentration in Moles Trail Amount of Gas Produced in Time 0secs 20secs 40secs 60secs 80secs 100secs 120secs.
While conducting the preliminary experiment, we faced a few problems. One main problem was that different molar solutions were not provided. This meant that we had to make our own molar solutions from a basis of 2 molar hydrochloric acid. We had decreased the molarity by adding different volumes of distilled water. Below shows a table of the volumes used to make the different solutions: Molar Solution of Hydrochloric Acid Amount of 2 Molar Hydrochloric Acid (cm3) Amount of Distilled Water (cm3) Total Volume (cm3).
We had used simple mathematics to lower the molarity of the solutions, using proportion. Below I have shown an example of the calculations I have used to work out the molarity of solutions: To make an accurate solution we needed exact amounts of hydrochloric acid and distilled water. To do this we had to add a few items to the equipment list, which are listed below: Distilled Water – To use to decrease the molarity of the hydrochloric acid solutions.
Pipette – To measure accurate amounts of distilled water and hydrochloric acid while making different molar solutions. Glass Rod – To stir the solution to evenly spread the two different solutions. While conducting the preliminary experiment we faced a few difficulties. These were: While inserting the rubber bung the gas syringe reading jumped – increasing the reading. This was due to the increase in pressure while inserting the bung. This meant that we had to minus a result (the amount increased while inserting the bung) after recording the results. We had no solution to this problem so we continuously had to minus the reading.
While measuring out the different concentrations, the measuring cylinder used started at a reading on 10ml. This meant that we had to make large bulks of each concentration – 100cm3 instead of the 20 cm3 that we had to use for the experiment. While measuring out the solutions of hydrochloric acid and distilled water we measured until the bottom of the meniscus was aligned to the reading, meaning that the results would be reliable. While collecting the data we were provided with different types of gas syringes. As different gas syringes were used, it caused a variance in our results.
This meant that some results had to be eliminated due to the high variance between other results. This meant that we had taken longer time than needed as some results needed to be repeated. Additionally I decided to use large sized chips as by having a larger surface area per chip, the overall surface area would be the same. Also I decided to use three chips that weighed to 2 grams. This meant that the average weight would be similar. This would keep the variables in control. I have noticed that there is a difference of results from my preliminary results and my final results.
I have concluded this change to the difference in size of the conical flask. As we had used a large sized flask it meant that less gas was measured in the syringe due to gas being trapped at the top of the conical flask. This meant the preliminary results that we got were slightly lower than expected. Before I begun my final investigation I made a few changes to my method. These changes were: I started measuring the levels of solutions at the bottom level of the meniscus. Used more marble chips so the average surface area per chip was similar. Measured each molar solution to 100cm3 instead of 20cm3.
University/College: University of California
Type of paper: Thesis/Dissertation Chapter
Date: 12 October 2017
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