2016 Destroyer Orgo #22

[nextgendental]

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Question: An organic chemist wanted to deliver 15.6 ml of a liquid in an experiment. Which should she employ?
a) Graduated Cylinder
b) buret
c) pipet
d) volumetric flask
e) condenser

I picked graduated cylinder but the answer was pipet. The explanation says the pipet is calibrated to deliver a specific volume of a liquid when filled to the mark and allowed to drain. I think thats a fair explanation but I don't understand why the graduated cylinder wouldn't be a good choice. I guess I picked A because I saw 15.6 ml and it seemed pretty precise and I don't remember making such precise additions using a pipet during Ochem lab. A better explanation would be greatly appreciated.

 

[DAT Destroyer]

Question: An organic chemist wanted to deliver 15.6 ml of a liquid in an experiment. Which should she employ?
a) Graduated Cylinder
b) buret
c) pipet
d) volumetric flask
e) condenser

I picked graduated cylinder but the answer was pipet. The explanation says the pipet is calibrated to deliver a specific volume of a liquid when filled to the mark and allowed to drain. I think thats a fair explanation but I don't understand why the graduated cylinder wouldn't be a good choice. I guess I picked A because I saw 15.6 ml and it seemed pretty precise and I don't remember making such precise additions using a pipet during Ochem lab. A better explanation would be greatly appreciated.

Let us pretend that we are in organic lab. The professor asks you to transfer liquid hexane from one flask to another .

Surely you would not bring over a buret for the transfer Now would you really expect that a graduated cylinder would be as useful and accurate as a pipet ? Not a chance. The graduated cylinder is not only more cumbersome, but would not be nearly as accurate. Bottom Line.... For transfers use a pipet, for measuring volumes such as in a titration use a buret.

I hope this helps.

Dr. Romano

 

[O Gaúcho]

When is a graduated Cylinder preferred?

 

[Likkriue]

You should go to chadsvideos.com and go to his gen chem laboratory video. He will tell you all about why graduated cylinders have such a large margin of error.

 

[DAT Destroyer]

When is a graduated Cylinder preferred?

A graduated cylinder is generally used when you want to measure the density of an object. The amount of fluid displaced will be equal to the volume of the object. You likely did this experiment in freshman chemistry. Graduated cylinders can also be used to measure volumes of a sample when accuracy is not all the critical.

Hope this helps.

Dr. Romano

 

[nextgendental]

Thank you so much @orgoman22


Sent from my iPhone using SDN mobile

 

[DAT Destroyer]

Thank you so much @orgoman22


Sent from my iPhone using SDN mobile

Glad I could help!

Dr. Romano