Study Questions And Answers.docx

Study questions and answers. 1. Which of the two pipettors that you used was the more accurate? Explain. a. Based on the errors of each pipettors, it showed that the 100µl has higher percent error and the 1000µl pipettor has the lower percent error. It can be indicate that the 1000µl is more accurate than 100µl pipettor. This is because the smaller percent error indicate the higher accuracy. 2. Which of the two pipettors that you used was the more precise? Explain. a. Precision is the closeness of the set values obtained from identical measurements of the same quantity. It is related to the standard deviation of the measurements. So, the lower standard deviation means the more precise the equipment. In this experiment, 1000µl pipettor has a lower standard deviation rather than 100µl pipettor. So, it can be concluded that 1000µl pipettor is more precise than 100µl pipettor. 3. What are the take-home messages from this exercise? Give three specific things that you learned from this lab. 4. Without checking the accuracy of the given pipettor, would you predict that it is better to use a 10µl or 1000µl pipettor to pipet 10µl? Why?

1. Which of the two pipettors that you used was the more accurate? Explain. a. Based on the errors of each pipettors, it showed that the 10µl has higher percent error and the 1000µl pipettor has the lower percent error. It can be indicate that the 1000µl is more accurate than 10µl pipettor. This is because the smaller percent error indicated the higher accuracy. 2. Which of the two pipettors that you used was the more precise? Explain. a. Precision is the closeness of the set values obtained from identical measurements of the same quantity. It is related to the standard deviation of the measurements. So, the lower standard deviation means the more precise the equipment. In this experiment, 10µl pipettor has a lower standard deviation rather than 1000µl pipettor. So, it can be concluded that 10µl pipettor is more precise than 1000µl pipettor. 3. What are the take-home messages from this exercise? Give three specific things that you learned from this lab. a. The important thing is to handle the micropipettors carefully during withdraw the solution from the 1.5ml tubes, because of the bubble inside. Second, we need to use a suitable micropipettors according the volume that we need to measure because there might be an error if we choose the wrong micropipettor. Lastly, Wrong handling technique or careless during using the micropipettors will be affected the result of whole experiment. 4. Without checking the accuracy of the given pipettor, would you predict that it is better to use a 10µl or 1000µl pipettor to pipet 10µl? Why? a. It is better to use 10µl micropipettor to pipet 10µl because it is within the range of 10µl. 5. How do you make 200mL of .01 M solution of the substance that has a molecular weight of 121.1g/mol? a. 0.1 M = mol/0.2L Mol = 0.02mol Mass of substance = 121.1 g/mol * 0.02mol Mass of substance = 2.422 g

6. If you take 10mL of the solution from question 5, add 90mL of water, and then take 5mL of the mixture and bring it to 25mL, what will be concentration of the final solution in molars, milimolars and micromolars? a. 10ml (0.1 M) + 90ml = 100ml mixture of M (10ml/100ml)*0.1M = 0.001M 5ml (0.01M) + 20ml = 25ml of M (5ml/25ml) * 0.01M = 0.002 M In milimolars = 2 mM In micromolars = 2000 µM