같은 곳에서

 안녕하세요 다홍빛하늘입니다. 오늘은 질량보존의 법칙과 실험에서의 한계시약 찾기, 화학식 찾기 등의 내용을 담은 실험 레포트로 찾아 뵙네요.  이 실험에서는 NaHCO3 + CH3COOH->CH3COONa +CO2+H2O 이 반응식을 통하여 나오는 CO2의 부피를 살펴보며 theoretical amount가 어느지점인지 추측하고, 실제와 같은지를 확인해볼 수 있습니다. 레포트의 저작권은 다홍빛하늘에게 있으며, 불펌 및 무단 공유를 일체 금함을 알려드립니다. 참고는 괜찮습니다. 참고하셨다면 댓글 달아주시면 더욱 좋구요 :)

1. Introduction

▶Complete sentences summarizing purpose of experiment. These sentences should include clear explanation both concepts and techniques.

 This experiment was designed for conservation of mass and limit reagent identification. Its chemical reaction formula is NaHCO3 + CH3COOH->CH3COONa +CO2+H2O, At part 1, we measured about limit reactant of each reactions. Also we measured starting mass and ending mass to identify weather the law of conservation of mass is established. And part 2, we measured mass of CO2(Actual yield) to compare with theoretical yield. Finally we can take % yield in this chemical reaction.DY

2. Experimental 

▶The procedure section should reference the lab manual and describe how you did your experiment and include any changes made to the procedure during the lab.

Part 1 <Law of conservation of mass & Limiting reagent>

1. Weigh and set six amounts of baking soda.

2. Put the six different masses of baking soda into six balloons using a small plastic funnel. Make sure the baking soda locates to the bottom of the balloon.

3. Using the pipette to accurately measure and transfer to put 20.0mL vinegar (6% acetic acid, CH3COOH) into each flask.

4. Weigh the flask and Record total mass of all objects.

5. Attach the filled balloons to the mouth of the flasks. Ensure that the substance in the balloon and flask are not mixed.

6. Lift balloons to the flasks so that the contents of the balloon mix with the flasks contents simultaneously for the simultaneous progress of the reaction. (Do not let any gas escape from the system that you set up and be careful not to remain NaHCO3 powder in balloons.)

7. Observe the size of the balloons after the reactions. Measure the diameter of each balloon.

8. Record your observations for each flask and weight all objects carefully.

Part 2 <Actual and theoretical yields>

1. Weigh 2 g of baking soda and record the mass.

2. Prepare 100 mL erlenmeyer flask and measure the 20 mL of 1.00 M vinegar.

3. Deliver the vinegar to flask and weigh the mass of flask and 20 mL of 1.00 M vinegar.

4. Pour the NaHCO3 powder to beaker. When the bubbling finished, stir the solution in the beaker to make the reaction complete and remove the bubbles made by CO2.

5. Weigh the beaker containing the solution and record the mass. 

6. Repeat the experiment two times using 20 mL acetic acid (vinegar) and 2 g of baking powder.

7. Using these data, we compare to theoretical yield and actual yield. And calculate percentage yield.

3. Results 

▶Part Ⅰ: Post lab calculations: complete the table with your lab data.

1) Find the number of moles of baking soda used in each reaction.

2) Decide which chemical is the limiting reagent in each flask reaction

3) Decide how many moles of carbon dioxide were produced in each flask.

▶ partⅡ: Calculate the % yield 

4. Discussion & Conclusion

1) Part Ⅰ: Record your results on the data table. How did your result support or violated the Law of Conservation of Mass? Did this lab prove the law of conservation of mass? Explain & use data to support your answer. 

Said to be frankly, based on this experiment alone, that violated the Law of Conservation of Mass because of gap between starting mass and ending mass. But whole mass of that experiments are more than 70g, so this amount changes are small enough to be ignored. So that results of the experiment does not violate the law of conservation of mass.

2) What are the sources of error in the experiment? (List all possible errors found in this experiment.)

•      Part Ⅰ

Mass gap between starting mass and ending mass is due to the leakage of generated CO2 gas. The reason came to think of this is because the mass of the CO2 generated and the corresponding error have a similar relationship. Maybe It is caused by pressure of CO2. This is because the error value from the point where the mass of the product is equal is almost constant, and the error value increases as the amount of the product increases.

 We have considered whether the remaining baking powder in the balloon affects it, but we have concluded that the law of conservation of mass does not affect the mass value as the amount of product is small.

•      Part Ⅱ

  It is expected that there will be spilled powder until it is put into vinegar after measurement. Since the mole number of acetic acid in the vinegar is smaller than the mole number of NaHCO3, NaHCO3 is left to be left even if it reacts. Therefore, we can suppose that acetic acid in vinegar is less than 2.0*10^-2 mol.

DY