Question 6 please.... Discussion:You need to talk about the accuracy and precisi

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Question 6 please.... Discussion:You need to talk about the accuracy and precision of the results of our group compared with actual value and the class data.Actual value is founded by divide molar mass of oxalate over mass of green crystal and change into %. The group value you will need to find use the experimental data.

METHOD AStandardization of Potassium Permanganate Solution Wear your disposable gloves, safety goggles, and apron. Set up the magnetie stirrer apparatus. Caution: Permanganate solution is toxic and corrosive. Wipe up spills promptly. Flush with tap water if spilled on skin or clothing. Use soapy water with a brush to clean the burette. Rinse the burette twice with 5-mL of deionized water. Rinse your burette three times with a small portion (-2-mL) of permanganate solution and then fill it. You should not start exactly at zero level on the burette and only take (in a clean conditioned 100 ml beaker) as much permanganate solution as you need to fill the burette. Record your starting value. (NOTE: All permanganate and oxalate wastes should be placed in the labeled waste container in the hood. Do not pour them down the sink!!) Since you will not be able to read the bottom of the meniscus due to the intense color of the permanganate ion, read the volume at the top of the meniscus. 1. Calculate the number of grams of Na C 0, that is needed to titrate with approximately 30- mL of-0.01 M KMnO, while making sure to show the 2:5 reaction ratio given in equation 8. 5 mol C20 so the critical ratio is: 2 mol MnO4 2. On th e analytical balance weigh out an amount that is close to what you have calculated above, recording to the correct precision 3. Dissolve this amount of Na C:Os in 150-mL of 1 M H SO solution. 4. Warm the solution on a hot plate stirer to about 60 °C. While the solution is still warm, titrate it against KMn0 to a permanent faint pink color (the pink color must last at least 30 seconds). You will notice that when the first few drops of KMnO are added to Na C:0, a pink color will appear. This color, in fact, may persist for more than 30 seconds even with the magnetic stirrer mixing the solution. This is not the end point of the titration. 5. Repeat this titration two more times, 6. After standardization, the KMnOs should be used immedi ately since it is not very stable mass Oxalate-2 95

Explanation / Answer

The term accurary refers to the closeness between actual value and the measured value. More closer the measured value is to the actual value, more accurate is the result. But the actual value is not not given here.

Now, the precision refers to the closeness between individual measure values. it means that, if the individual measured values are more closer to each other, the results are more precise. In the given case, since the measured values of avg Ox % ranges from 53.8% to 631%. so, we can not say that this analysis is precise. A measurement has to be both accurate as well as precise.

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