Measurements: Accuracy and Precision Essay Sample

1. Convert the length and tallness measurings for the package that contains the aluminium shooting from units of centimeter to units of millimeter utilizing the unit-factor method. Cm is converted to mm utilizing the equation mm= cm/0. 10000. So. when you place the 5 or 6. 5 cm measuring in the equation you get 5cm= 50 millimeter and 6. 5cm = 65 millimeter. 2. Convert the temperature measurings for the faucet H2O and the ice H2O from oC to oF. utilizing the undermentioned equation: oF = 1. 8 ( oC ) + 32. Using the above equation. 26? hundred = 78. 8? degree Fahrenheit and 7? c= 44. 6? f 3. Convert the volumes of the H2O in the 10-mL and 50-mL calibrated cylinders from milliliter to L. utilizing the unit-factor method.

Using the equation to covert milliliter to l which is L= mL/1000. we find that 7. 1 mL = 0. 0071000L and 7ml = 0. 0070000L 4. Looking at your measurings for the volumes of H2O in the 10-mL and 50-mL calibrated cylinders. are your values indistinguishable? Discuss at least two grounds why the measurings were non indistinguishable. The measurings were away by merely a hair. Why? One of the grounds could be that I couldn’t successfully acquire all of the H2O from the 10ml cylinder to the 50ml cylinder. Some H2O was traveling to be retained in the cylinder or in the pipette. Part II ( Questions 5-11 are deserving 10 points each. )

5. Calculate the volume of the 50mL graduated cylinder utilizing your measurings of diameter and tallness. utilizing the expression V = ? r2h ( r=? diameter ) . This is your experimental value. Assuming the recognized value of the volume of the calibrated cylinder is 50. 00 milliliter. cipher the per centum mistake of your volume computation. utilizing the undermentioned expression: Given the tallness. 7. 2 centimeter. and the rate. 2. 75 centimeter. the experimental volume of the cylinder is 171. 06 milliliter. Percent Error = /accepted value – experimental value/x 100

recognized value
( 50. 00 ml – 171. 06ml/ 50 ) X 100 = 242. 12 %

6. Calculate the mass of 10ml of H2O in the calibrated cylinder utilizing 1/5 the volume calculated in # 5 above and the denseness of H2O of 1. 00 g/mL. Calculate the mass of the H2O utilizing the expression for denseness: Density = mass volume

The volume is 171. 06. Dividign it into 5 brings the mass to 34. 21. 34. 21/171. 06 = . 20. So therefore the denseness peers. 20 or 20 % .

7. Using 10. 0 g as the recognized value for the mass of the H2O. and the mass calculated utilizing water’s denseness in # 6 above as the experimental value. cipher the per centum mistake of your mass computation. utilizing the same expression as in # 5 above. ( 10 g -34. 21 g / 10 g ) X 100 = 242. 1

8. Calculate the volume of aluminium shooting added to the graduated cylinder. utilizing the undermentioned expression: ( Volume of H2O + Al ) – initial volume of H2O = volume of Al changeable Volume of the H2O is 10 milliliter. So ( 18 ) – 10 = 8 milliliter.

9. Calculate the experimental value for denseness of the aluminium shooting based on its mass ( given on the exterior of the package ) every bit good as its volume calculated in # 10 above. utilizing the undermentioned expression: Density of Al = mass of Al shot/ volume of Al shooting

Mass = 19. 9. volume 8
Density = 2. 4

10. If the recognized value for the denseness of aluminium is 2. 70 g/mL. cipher the per centum mistake of your denseness computation. utilizing the expression listed in # 5 above. ( 2. 70 – 2. 4 / 2. 70 ) X 100 = 11 % mistake

11. What were the possible beginnings of mistake in this experiment? Why is it necessary to cognize the mistake of one’s measurings? Suggest some ways of minimising mistake. if you were to reiterate the experiment. Bing 100 % certain that there is merely 10ml of H2O in the cylinder when you start the experiment every bit good as utilizing the proper utensils needed are a few ways to minimise mistakes. Part III

12. Supply your value for the either the weight of the Earth. the volume of the Atlantic ocean. or the temperature of the Sun ( in scientific notation ) along with the commendation. Then. demo both transitions you chose to finish for this value. Show all work for your transitions. ( 12 points ) The weight of the Earth. per Google. com. is 5. 972E24 Kg. This is written in scientific notation as 5. 97 ten 10 ^24 13.

Explain why the usage of scientific notation in chemical science is really of import. ( 10 points ) It helps to minimise the sum of Numberss that are drawn out so that people can work quicker every bit good as read the information more accurately. 14. Give an illustration of a clip when you have used unit transitions in mundane life. and explicate why that cognition is utile. ( 12 points ) As a CNA in a infirmary. I would frequently hold to take peoples weights every bit good as their temperature. IF the graduated table was non on the proper scene I would necessitate to change over their weight in lbs to kilograms for charting. The same thing happened often with temperatures. I would take a patients temperature. and so recognize it was in Celsius on the machine and demand to change over it to Fahrenheit.

Leave a Reply

Your email address will not be published. Required fields are marked *