SCIN131 Lab Assignment 2
Lesson 2 Lab: Weighing on an Analytical Balance & Distillation
PART 1
Begin by viewing the following Thinkwell video
15.1.8 CIA Demonstration: Weighing on an Analytical Balance
After you watch the above video, answer the questions below in sufficient detail:
(a) (2 pts) What are the features of an electronic balance? Include all of those discussed in the video.
Answer: There were two features of an electronic balance discussed in this video. First there is the electronic read out which makes the measurement very accurate and the tare feature which can reset the balance to zero when something such as a container is still on the balance (Yee, n.d., Weighing…).
(b) (1 pts) What does “tare” mean? What is the importance of the ability to 'tare' when taking the mass of your sample? Be specific.
Answer: Tare is used to reset a balance to zero in order to get only the weight of a sample, not of a sample and container (Yee, n.d., Weighing…). It is important because accuracy and precision are both very important when measuring. The tare feature makes the measurement more accurate. It also allows just the substance to be measured without the substance having to be put directly on the balance.
(c) (2 pts) What is the difference between weigh boats and weigh paper, and in what circumstances should you use each? Be specific and detailed in your answer.
Answer: Weighing boats are more expensive and they are used to measure larger amounts whereas weighing paper is cheaper and used to measure smaller amounts (Yee, n.d., Weighing…). Weighing boats are small plastic boats and weighing paper are small squares of very thin wax paper that can be folded (Yee, n.d., Weighing…).
(d) (2 pts) According to the lab video, what is the difference in how you weigh smaller amounts vs. larger amounts, and what is the role of the scoopula in this? Explain in detail.
Answer: When weighing smaller amounts weighing paper is used and in weighing larger amounts weighing boats are used
PART 1
Begin by viewing the following Thinkwell video
15.1.8 CIA Demonstration: Weighing on an Analytical Balance
After you watch the above video, answer the questions below in sufficient detail:
(a) (2 pts) What are the features of an electronic balance? Include all of those discussed in the video.
Answer: There were two features of an electronic balance discussed in this video. First there is the electronic read out which makes the measurement very accurate and the tare feature which can reset the balance to zero when something such as a container is still on the balance (Yee, n.d., Weighing…).
(b) (1 pts) What does “tare” mean? What is the importance of the ability to 'tare' when taking the mass of your sample? Be specific.
Answer: Tare is used to reset a balance to zero in order to get only the weight of a sample, not of a sample and container (Yee, n.d., Weighing…). It is important because accuracy and precision are both very important when measuring. The tare feature makes the measurement more accurate. It also allows just the substance to be measured without the substance having to be put directly on the balance.
(c) (2 pts) What is the difference between weigh boats and weigh paper, and in what circumstances should you use each? Be specific and detailed in your answer.
Answer: Weighing boats are more expensive and they are used to measure larger amounts whereas weighing paper is cheaper and used to measure smaller amounts (Yee, n.d., Weighing…). Weighing boats are small plastic boats and weighing paper are small squares of very thin wax paper that can be folded (Yee, n.d., Weighing…).
(d) (2 pts) According to the lab video, what is the difference in how you weigh smaller amounts vs. larger amounts, and what is the role of the scoopula in this? Explain in detail.
Answer: When weighing smaller amounts weighing paper is used and in weighing larger amounts weighing boats are used
References: Diffen. (n.d.) Accuracy vs. Precision. Retrieved from http://www.diffen.com/difference/Accuracy_vs_Precision Tro, N.J. (2011). Essentials Introductory Chemistry (4th ed.) (pg 129). Boston: Pearson Prentice Hall. Yee, Gordon. (n.d.) CIA Demonstration: Distillation [Thinkwell]. Retrieved from http://my.thinkwell.com/students/content/videos.cfm?#l2087341 Yee, Gordon. (n.d.) CIA Demonstration: Weighing on an Analytical Balance [Thinkwell]. Retrieved from http://my.thinkwell.com/students/content/videos.cfm?#l2087341