Posted by Steve on .
Assume the optimal coffee drinking temperature is 75°C, and further assume coffee has the same heat capacity and density as water.
a. How much energy is required to raise the temperature of 1 cup (0.237 liters) of coffee initially at 25°C to the optimal temperature?
b. How much energy is required to heat the coffee to 95°C?
c. The coffee is cooled back down so that the mixture of coffee and melted ice has the optimal temperature. If the ice started at ‐3°C, what mass (m=?) of ice is required?
d. If the water used to make the ice started at 25°C, how much energy was required to freeze it and cool the ice to ‐3°C in the first place?
e. How much energy was wasted by overheating the coffee? This will be the overheating energy, plus the energy to make the ice, less the energy to heat it to the optimal temperature. What is the ratio of wasted energy to useful energy?
I will be happy to critique your thinking.
you have posted these questions under several names, I can only assume you are answer grazing.
a. Q=(4.18)(237)(50)=49533 J
b. Q=(4.18)(237)(70)=69346.2 J
c. Q=(4.18)(237)(Tf-95)+(4.18)m(3) + m(334) +cm(Tf)=0
d. Q=(4.18)(237)(-25) + (237)(334) + (4.18)(237)(-3)
e. Don't know