Re: Thermodynamics B/C
Posted: September 8th, 2017, 2:11 pm
I can't figure out how the ice water is any worth it at all. Unless even the best devices do a very very crappy job insulating I don't see the possible 5 points being worth it
It's ice water, not ice. One pretty cool feature of ice water is that it remains at a constant 0 degrees Celsius as long as there are both water and ice in the mixture (because that means the ice is melting). Just like boiling water is a constant 100 degrees Celsius (Obviously there are ways to change this due to pressure, impurities, etc, but for our purposes it's good enough).retired1 wrote:n. the big problem here is ice is not 0 degrees C. it has to be colder to freeze. .
Perhaps you aren't used to running this event in parallel? The typical way i recommend this event is as follows (let's assume 10 teams and 30 mins cooling time and a 50 minute time block):retired1 wrote:Big problem : Time. For B it has a 5 min set up, a 30 min set or cool down time, 20 min for testing and typically there are 8 teams per period and it takes time to get the hot water to every time. That is very near the total time of each period. add in the ingress/egress of each set of teams and the supervisor has to review what is logged for each team.
Big problem!
This would be a safe assumption to make mostly because it is easy to see event supervisors just only doing one pour to save time instead of pouring a 100 mL and then pouring another 25 mL. Of course this might be true for regional and maybe even states but for events run by scioly alumni, well these are the kind of people who wouldn't mind the second pour just to throw some competitors of their game.Ashernoel wrote:Because most graduated cylinders are <=100 ml, wouldn't it be safe to **assume** that there is much higher likelihood of the volume of water being between 50 and 100 than between 100 and 150?
The recommendation I have is for the event supervisor to have enough thermometers to leave them in all the beakers (i.e. in the example I listed that would be 20 thermometers). Most school labs have tons of them sitting around so they aren't a big expense. That alleviates the time crunch regarding the 20 seconds wait period.retired1 wrote:You can get graduated cylinders in virtually any volume.
Chalker- I had not considered testing during the "set" period. Sounds good, hope regionals and states have lots of good help.
One oops in that plan is that the thermometer must remain (by the rules) in each of the 20 beakers for 20 seconds. That makes for tight scheduling or multiple well trained assistants.
Will be interesting to see how well it works. At the nationals held in Florida, it took a lot longer than 30 seconds to dispense the hot water into 2 beakers for each c\student.
The last page of that test was tough.
WhatScience? wrote:This would be a safe assumption to make mostly because it is easy to see event supervisors just only doing one pour to save time instead of pouring a 100 mL and then pouring another 25 mL. Of course this might be true for regional and maybe even states but for events run by scioly alumni, well these are the kind of people who wouldn't mind the second pour just to throw some competitors of their game.Ashernoel wrote:Because most graduated cylinders are <=100 ml, wouldn't it be safe to **assume** that there is much higher likelihood of the volume of water being between 50 and 100 than between 100 and 150?