A non-conducting vessel contains a liquid of mass 70 g at 25º C. Another 70.0g of the same liquid at 35ºC is quickly poured into the vessel. Determine the final temperature of the mixture
A
15ºC
B
20ºC
C
30ºC
D
40ºC
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
Heat gained by 25º C body = Heat lost by 35º C body
M\(_c\) c \(\delta\)\(\theta\) = M\(_h\) c\(\delta\)\(\theta\)
70 x c x (f - 25) = 70 x c x (35 - f)
where f = final temperature
f - 25 = 35 - f (f and 70 cancel out)
2f = 35 + 25 = 60
f = \(\frac{60}{2}\) = 30ºC
Source: WAEC / JAMB / NECO Classroom Archive (Record #72075)