Presentation is loading. Please wait.

Presentation is loading. Please wait.

Additional Practice Feb. 12, 2014. Mixing Liquids at Different Temps Two Equal Quantities (1 liter each) of Liquids are at different Temperatures One.

Similar presentations


Presentation on theme: "Additional Practice Feb. 12, 2014. Mixing Liquids at Different Temps Two Equal Quantities (1 liter each) of Liquids are at different Temperatures One."— Presentation transcript:

1 Additional Practice Feb. 12, 2014

2 Mixing Liquids at Different Temps Two Equal Quantities (1 liter each) of Liquids are at different Temperatures One is at 20 °C the other is at 40 °C What is the final temperature after the two are allowed to come to Thermal Equilibrium in a 2 liter bucket?

3 Solution #1 “Cheap Short Cut” Since the two quantities are the same add the two temps and divide by 2 20 +40 =60/2 = 30 °C

4 Preferred Solution Approach the problem form the standpoint of Specific Heat Q Q1 +Q2 = 0 since there is no heat added or lost to the system. Let T f be the final temperature of the bucket and T 1 and T 2 be the initial temperatures of Each liter. Then the ΔTs will become ΔT 1 = T f -T 1 and ΔT 2= T f- T 2

5 Preferred Solution (cont.) Q 1 = m 1 x C 1 x ΔT 1 and Q 2 = m 2 x C 2 x ΔT 2 Substituting for ΔT 1 and ΔT 2 Q 1 = m 1 x C 1 x (T f -T 1 ) Q 2 = m 2 x C 2 x (T f -T 2 ) Q1 + Q2 =0 m 1 x C 1 x (T f -T 1 ) + m 2 x C 2 x (T f -T 2 ) = 0

6 Preferred Solution (cont.) m 1 x C 1 x (T f -T 1 ) + m 2 x C 2 x (T f -T 2 ) = 0 m 1 C 1 T f -m 1 C 1 F 1 +m 2 C 2 T f -m 2 C 2 T 2 =0 m 1 C 1 T f -m 1 C 1 F 1 = -(m 2 C 2 T f -m 2 C 2 T 2 ) m 1 C 1 T f -m 1 C 1 F 1 = m 2 C 2 T 2 -m 2 C 2 T f 1x1x T f - 1x1x T 1 = 1x1x T 2-1x1x T f (Simplify) T f -T 1 =-T f +T 2 Add T f and T 1 to both sides 2T f = T 1 + T 2 Solve for T f Tf = (T1+T2)/2 Only when M1=M2 and C1=C2 Tf= (20 + 40) /2 = 30 °C


Download ppt "Additional Practice Feb. 12, 2014. Mixing Liquids at Different Temps Two Equal Quantities (1 liter each) of Liquids are at different Temperatures One."

Similar presentations


Ads by Google