Question

An eccentric chemistry professor (not mentioning any names) stops in every day and orders 200ml of Sumatran coffee at precisely 65.0°C. You then need to add enough milk at 7.00°C to drop the temperature of the coffee, initially at 85.0°C, to the ordered temperature. Calculate the amount of milk (in ml) you must add to reach this temperature. In order to simplify the calculations, you will start by assuming that milk and coffee have the specific heat and density as if water. In the following parts, you will remove these simplifications. Solve now this problem assuming the density is 1.000 g/ml for milk and coffee and their specific heat capacity is 4.184 J/(g ºC). How much milk will you add?

Answer 1

Answer:

68.97g of milk must be added

Explanation:

To solve this problem we need to use the equation:

Q = C*m*ΔT -Coffee cup calorimeter equation-

This equation relates mass and change in temperature with heat of solution, Q.

The energy that decreases in the milk is the same that increases in the milk. That is:

Q(milk) = Q(tea)

Using the equation:

4.184J/molK* Mass milk * (65.0°C - 7.00°C) = 4.184J /molK * 200g (Tea) * (85.0°C - 65.0°C)

Mass milk * 58.0°C = 200g * 20.0°C

Mass milk = 4000g°C / 58.0°C

Mass milk =

68.97g of milk must be added