Imagine that you have two cups, one containing 1510 g of water and the other one
ID: 1475861 • Letter: I
Question
Imagine that you have two cups, one containing 1510 g of water and the other one containing 2180 g of an unknown liquid. The specific heat of water is 4.19 J/g·°C. You use two identical immersion heaters to heat the water and the unknown liquid simultaneously. Assume that all the heat from the heater is used to heat the content of the cups.
(a) You started heating the water and the unknown liquid at the same time. If the temperature of the unknown liquid is increased from 16.2 °C to 21.7 °C while the water temperature is increased from 16.2 °C to 34.6 °C, what is the specific heat of the unknown substance?
_____J/g·°C
(b) If the power of the heaters you used is 176 W, how long have you heated the liquids?
_____ minutes
Explanation / Answer
a)
Total Heat Supplied is the same for both liquids in cups
m1c1delta T1 = m2 c2delta T2
1510*4.19*(34.6-16.2) =2180*(21.7-16.2)c2
c2 = 1510*4.19*(34.6-16.2) /2180*(21.7-16.2) = 9.7J/g·°C
b)power = workdone/time,
time = workdone / power = 1510*4.19*(34.6-16.2)/ 176 =661.44 sec = 11.02 minutes