2014 Final 1C

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Blake_Katsev_2E
Posts: 113
Joined: Wed Sep 21, 2016 2:57 pm

2014 Final 1C

Postby Blake_Katsev_2E » Tue Mar 14, 2017 4:26 pm

Why would there be 3 sig figs in the answer if the question had 25 degrees C and 47 degrees C?

Stephanie_Thai_2C
Posts: 10
Joined: Fri Jul 22, 2016 3:00 am

Re: 2014 Final 1C

Postby Stephanie_Thai_2C » Tue Mar 14, 2017 5:40 pm

I believe there are 3 sig figs in the answer because at one point in the equation, there is adding/subtracting, which has different sig fig rules from multiplying/dividing. When dealing with addition/subtracting, you take the smallest number of decimal places which will be 3 sig figs, so when you divide it later to find the enthalpy of vaporization, the answer will have 3 sig figs.

Sangita_Sub_3H
Posts: 23
Joined: Sat Jul 09, 2016 3:00 am

Re: 2014 Final 1C

Postby Sangita_Sub_3H » Sat Mar 18, 2017 12:52 am

For this question, the solution in the course reader says q = m*C*delta T + 1/2*m*(enthalpy of vaporization). Why is the enthalpy of vaporization multiplied by 1/2?

Nikhil_Madan_3C
Posts: 34
Joined: Wed Sep 21, 2016 3:00 pm
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Re: 2014 Final 1C

Postby Nikhil_Madan_3C » Sat Mar 18, 2017 2:03 am

It is multiplied by 1/2 because the questions says that Ron "realizes that half of his 255 g forgetfulness potion has boiled away. Therefore, you would multiply the mass by 1/2 since only half of it was converted into vapor.


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