Volumetric Analysis and Accuracy Introduction: The purpose of this lab in to increase awareness of accuracy of the equipment that you are using in the laboratory as well as systematic and random errors. Through the titration of hydrochloric acid with standard anhydrous sodium carbonate the accuracy of the equipment was tested to discover the difference in concentration over the five trials conducted. Method: The method that was given in the Chemistry 306 Laboratory was followed from page 14 – 16. The standard of hydrochloric acid was made to a concentration of (0.1008 ± 0.0020) mol L-1. The amount of sodium carbonate in the conical flask from A-E was 0.113 g, 0.195 g, 0.1368 g, 0.1872 g and 0.1898 g respectively. Results: To obtain a concentration value for the HCl a solution of (0.1008 ± 0.0020) mol L-1 HCl was titrated with Na2CO3 with methyl orange to give a …show more content…
During the preparation of the 0.1 mol L-1 standard hydrochloric acid there is uncertainty associated with the balances and the 250 mL volumetric flask. The uncertainty associated with the balanced could be reduced by using more precise balances. The volumetric flask has a greater uncertainty associated with it. This could be reduced by using more precise glassware. During the standardisation against anhydrous sodium carbonate the balance has uncertainty associated with it again a more precise balance would reduce uncertainty. The largest contributor to uncertainty is the burette this could be lessened by better quality glassware. Uncertainty was reduced by all of the experiment taking place in the same environment so there was no difference in humidity and temperature. The same balance was used for every measurement in the experiment. Using a dropper to make sure the meniscus was as accurate as possible decreased uncertainty. The titration was repeated 5 times reducing random error that could have been associated with the
Apparatus: * 1 measuring cylinder * 1 test tube * 1 stop clock * A large gelatine cube containing indicator and NaOH * Hydrochloric acid ranging from 1-3 molars * A scalpel Diagram: Method: * Take the large gelatine cube and cut into 15 equal pieces * Place on piece of the cube into the test tube * Measure out 10mls of HCl in the measuring cylinder * Pour the HCl into the test tube with the gelatine cube and start the clock * Time how long it takes for the pink colour inside the gelatine cube to completely disappear * You will also notice that the cube dissolves slightly * Record your results and repeat this same process 3 times for each molar of acid: § 1 molar § 1.5 molar § 2 molar
I believe that a suitable procedure was followed that ensured that all inaccuracies in readings occurred due to human errors in reading. A syringe rather than measuring cylinders being used avoided errors in the measurements of volumes of solutions. This left no room for inaccuracies in not accounting for the meniscus as a syringe will leave no room for a meniscus and bears detailed volume readings, (to the nearest tenth of a cm3). This procedure yielded fewer inaccuracies meaning that results were more reliable.
In this experiment, there were several objectives. First, this lab was designed to determine the difference, if any, between the densities of Coke and Diet Coke. It was designed to evaluate the accuracy and precision of several lab equipment measurements. This lab was also designed to be an introduction to the LabQuest Data and the Logger Pro data analysis database. Random, systematic, and gross errors are errors made during experiments that can have significant effects to the results. Random errors do not really have a specific cause, but still causes a few of the measurements to either be a little high or a little low. Systematic errors occur when there are limitations or mistakes on lab equipment or lab procedures. These kinds of errors cause measurements to be either be always high or always low. The last kind of error is gross errors. Gross errors occur when machines or equipment fail completely. However, gross errors usually occur due to a personal mistake. For this experiment, the number of significant figures is very important and depends on the equipment being used. When using the volumetric pipette and burette, the measurements are rounded to the hundredth place while in a graduated cylinder, it is rounded to the tenth place.
Random errors reflect a low precision through high scatter. Increasing the sample size of the number of tablets used will produce more data that can be graphed, and from which a more reliable and representative line of best fit could be produced, ultimately minimising random errors. Additionally, increasing the number of trials for each number of reacting Alka Seltzer tablets would minimise random errors by helping to produce a more precise average change in mass. Modifying the method can also help minimise the effect of random errors, by obtaining more reliable results. For example, instead of cutting the Alka Seltzer tablets in half, whole Alka Seltzer tablets could have been used, and the amount of reacting HCl could have been increased to account for the increase in the number of tablets used for each ample. In doing this, the mass of the reacting Alka Seltzer tablets will be more consistent for each trial, and the state of subdivision of the tablets could be truly kept
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
Then, we multiply the result by 100 to get a percentage number. An example calculation from the 5.00mL pipet is: ((5.00mL - 4.9178mL)/5.00mL)*100 = 1.6438%. The percent error allows us to see which type of glassware is the most accurate at measuring substances. From our results, we concluded that the variable auto pipettor was the most accurate, since it had the lowest percent error, at 0.0500%. The volumetric pipet, volumetric flask, and burette, all had similar percent errors at 1.0430%, 0.6394%, and 0.6619%, respectively. These results indicate that these glassware types are still very accurate. Next, the graduated cylinder had a percent error of 1.6400%, which is still relatively low, indicating that the graduated cylinder is also very accurate. The beaker and erlenmeyer flask both had higher percent errors, at 7.5218%, and 9.4146%, respectively. The beaker and the erlenmeyer flask were not accurate at measuring substances. This is perhaps because they are larger, and are meant to hold larger volumes of water, or they are meant to contain and pour substances. After finding out
There is also the potential of human error within this experiment for example finding the meniscus is important to get an accurate amount using the graduated pipettes and burettes. There is a possibility that at one point in the experiment a chemical was measured inaccurately affecting the results. To resolve this, the experiment should have been repeated three times.
I will not add a catalyst to my solution and I will not stir my solution. · I will use 25cm3 of hydrochloric acid. · I will use 1g of calcium carbonate.
the chances of collisions increase thus giving a faster rate of reaction. Then the s Apparatus:. Beaker Hydrochloric acid Distilled water Measuring cylinder Pipette Test tubes Test tube rack Diagram:.. [ IMAGE] Method: The.. Measure out 10cm3 of hydrochloric acid, as the concentration requires. for each concentration its composition is.
The Effect of Temperature on the Rate of Reaction Between Hydrochloric Acid and Calcium Carbonate
vii. This would allow the determination of the percentage of citric acid in the lemon juice specifically, rather than the total acidity. The results of this could have been compared to those of the titration, and the contribution of citric acid to the overall initial acidity could have been determined.
We are trying to find out how much acid it takes to neutralise the alkaline. But there are many things that could affect my final result and I think that the main thing will be measuring the acid and alkali accurately so that the experiment was fair. Prediction We planned the experiment as a class and so we have all predicted that the same thing will happen to the results. But a few of us disagreed. and I was one of them.
Firstly, we need to keep the chemical at a constant concentration. So, in this experiment we have chosen to keep hydrochloric acid at a constant concentration (5cm3). We could have, however, used Sodium Thiosulphate as a constant, but we had chosen to use Hydrochloric acid. Next, we must make sure that the solution is kept at a constant volume throughout the experiment. If the volume is different, then it could give different results if it was at a constant volume.
second test tube also add 6 mL of 0.1M HCl. Make a solution of 0.165
In this experiment three different equations were used and they are the Stoichiometry of Titration Reaction, Converting mL to L, and Calculating the Molarity of NaOH and HCl (Lab Guide pg. 142 and 143).