Sunday, April 12, 2020

Finding the concentration of sodium carbonate Essay Example

Finding the concentration of sodium carbonate Paper Finding the concentration of sodium carbonate:Mass (Na2CO3 transferred to volumetric flask)= [mass (weighing bottle) + mass (Na2CO3)]-[mass(weighing bottle after emptying)]=15.24g 12.59g=2.65gMolar mass (Na2CO3)Na=23C=12O=162Na x 1C x 3O = molar mass= (2 x 23) + 16 + (3 x 16)=106Number of mols (Na2CO3) = mass/molar mass=2.65g/106=0.025molNumber of mols (Na2CO3) = concentration x volume10000.025 mol. = conc. x 250cm31000Concentration (Na2CO3) = 0.1 mol.dm-3ResultsTitrationInitial Burette Reading (cm3)Final Burette Reading (cm3)Difference (cm3)1 (rough)0.0032.0032.0025.0036.2531.2531.1032.3031.2040.0031.2531.25510.0044.3034.30The first and last results are not included in the average since the first is only a rough titration so that later ones can be more accurate and the last is an anomalous result.Therefore the average is:(31.25+31.20+31.25) / 3 = 31.23cm3We can now number of moles of calcium carbonate using this equation:Number of moles = concentration x volume1000=0.1251000=0.0025 mol.The following reaction took place:H2SO4(aq) + Na2CO3 (aq) Na2SO4 (aq) +H2O(l) + CO2 (g)There is a 1:1 ratio of sulphuric acid to sodium carbonate.Therefore the number of moles of H2SO4 will be the same as those of Na2CO3.Number of moles of H2SO4= 0.0025molsNow we can work out the concentration of H2SO4 with this equationNumber of moles = concentration x volume10000.0025 mol. = conc. x 25cm31000Concentration (H2SO4) = 0.08 mol.dm-3 (2 d.p.)Evaluating Evidence and procedures.The final titration was an anomalous result 34.30cm3. A result much larger than the average of 32.23cm3 (3.07cm3 larger). All the other results (apart from the first which is only a rough titration so that later ones can be more accurate) were 0.05 of the average.The anomalous result could be down to a number of reasons. Such as the conical flask not being rinsed properly, leaving a small amount of water in the bottom, diluting the solution further. There may also have been errors in the readings. Or simply missing the end point by not swirling enough or turning off the burette quick enough.Out of the 5 results collected 2 have been ignored, this leaves us with only 3 results to find an average with.Another factor to consider is percentage error.% Error = actual error/ size of measurement x 100The balance that was used has an error of + or 0.005g. 4 measurements were taken:12.57g% Error = 0.005/12.57100=0.04%15.24g% Error = 0.005/15.24100=0.03%12.59g% Error = 0.005/12.59100=0.04%2.65g% Error = 0.005/2.65100=0.19One drop from the burette has a volume of approx. 0.05cm3, this gives an error of + or 0.05. The average titre was 32.23cm3; therefore the following % error occurred:0.05/32.23100= 0.16%There may also be error when using the pipette, if used correctly the error is + or 0.06cm3 therefore:0.06/25100=0.24%The volumetric flask could also produce an error; if the bottom of the meniscus rests on the calibration line the error is 0.2cm3. So:0.2/250X100= 0.08%The largest % errors are produced when using the burette and pipette. Therefore more care is to be taken when taking readings from them.The total % error =0.78%. Therefore the results can be 0.78% larger or smaller than the results I collected: 0.78% of 32.23cm3= + or 0.25. Therefore the exact result is between 31.98and 32.48.The errors in procedure could arise in the following:* Solution in volumetric flask partially mixed.* Burette and pipette not rinsed properly* Conical flask not rinsed properly between titrations.* Acid not added drop by drop as the end point approached.* Swirling not a continuous action, allowing the end point to be missed.* Too much or too little indicator.The middle 3 results are the only results accurate enough to use as evidence. If I were to use these results as evidence I would only include the middle three results and then continue until I had 10 results within 0.1 of each other. The % error of the experiment was very small (0.78%) this means the three useable results appear to be reasonably accurate.There are many ways to improve the experiment:* More repetitions, the more repetitions you do the more accurate your end point should be and the average would be more accurate as you are taking into account more results.* Ensure the pipette, burette and volumetric flask readings are done at eye level on a horizontal surface. This makes the readings the readings more accurate.* Use a thinner burette so that changes in volume are even more noticeable and lowering % error.* Add the solution in drips rather than a steady stream. This would make the end point much more accurate.If the experiment is performed in pairs it would make the burette readings more accurate, as 1 person could swirl the solution and the other could handle the burette. This would allow the swirling to be constant as the burette handler could concentrate on finding the end point accurately.

Saturday, April 11, 2020

Sample Essay Scholarship - What Makes a Student Get a Scholarship?

Sample Essay Scholarship - What Makes a Student Get a Scholarship?The ability to get a sample essay scholarship is something that many individuals look forward to. With the help of one of these scholarships, they can obtain their dream of going to college. They must have some unique reason why they want to go to college so they can get a full ride scholarship.There are certain situations where a student can obtain a scholarship even without being able to write well or having outstanding grades. There are also other reasons why individuals may need to consider a scholarship.Sometimes individuals who struggle in school and/or have been through some different life events will be able to obtain a college scholarship. There are many benefits for individuals who have been through hardships, however you must consider what your particular situation is. In some cases, there are other scholarships that will give you a big advantage that will help you throughout college.Most students have to be self-motivated and focused to be successful at school. When one has a lot of academic challenges, they will be more determined to succeed. There are many individuals who find ways to make the most of their study times and keep studying so they do not run out of time.There are many different ways that individuals can use their funds, however it is important to make sure they use their money properly. If you spend your money on a frivolous purchase, you may regret it later. It is best to think long and hard about what your goals are.You can find various opportunities on the internet, as well as on your local newspapers or online. The following is a list of samples you can use as you search for your new college. These samples will assist you in being able to find the best scholarship for your financial situation.Although it is difficult to obtain these student loans, if you plan on getting one for your studies, you must understand that you will not always have the money that you need. Sometimes there are times when you will not be able to find enough money for your studies. By making sure that you follow through with your assignments and read your textbooks, you can finish your courses in no time at all.