Specific heat Concepts
What does each variable represent in Q=mC(Tf - Ti)?
Q=energy
m=mass
C= specific heat
Tf = final temp
Ti = initial temp
How much heat energy (in J) is required to raise the temperature of a 50.0 gram sample of water from 20.0∘C to 35.0∘C?
(water specific heat is 4.184 J/g C
3138 J
with SF: 3140 J
A piece of metal at 200.0°C is dropped into 300.0 g of water at 25.0°C. Final temperature is 30.0°C. The metal’s specific heat is 0.385 J/g°C. What is the mass of metal?
95.8 g
What was the objective of the calorimetry lab?
To determine the specific heat of the metal
True or false
A substance with high specific heat will be resistant to temperature change when energy is added
True
A 25.0-gram piece of an unknown metal absorbs 1,000 Joules of heat, causing its temperature to rise from 25.0∘C to 125.0∘C. What is the specific heat of the metal in J/g∘C?
0.4 J/g∘C
A 20.0 g metal at 80.0°C is added to 80.0 g of water at 10.0°C. Final temperature is 18.0°C. Find the metal’s specific heat, C.
2.16 J/g C
What is the name of the device used to measure heat transfer between the metal and water.
calorimeter
Substance X and Y are different materials. Both have the same mass. The same amount of energy is put into them.
Substance X has a final temp of 30C. Substance Y has a final temp of 60C. Which one has the lower specific heat and why?
Substance Y. It took the same amount of energy and the final temperature was higher.
40 g of aluminum (c = 0.90 J/g°C) cools from 100°C to 25°C. How much heat is released?
-2700 J
with SF = -3000 J
A piece of metal at 100.0°C is dropped into 200.0 g of water at 20.0°C. The final equilibrium temperature is 25.0°C. If the metal is copper (C of metal =0.385 J/g°C), what is the mass of the metal?
145 g
in -mC(Tf-Ti)1 = mc(Tf-Ti)1, why is one side negative and one side positive?
One substance is releasing energy, one side is absorbing energy
When two objects mix together, will their final temperatures be the same or different? Why?
The same. That mixture will go through thermal equilibrium and have the same temperature throughout.
3000 g gold bar (c=0.129 J/g∘C) at 99C is dropped into water and had a final temp of 47C. What is the energy that is absorbed by the water?
20124J
with SF: 20000 J
A 590 g brass sample at 98.0 C is dropped into 2800 g of water at 5.0 C. If the temperature of the mixture is 6.8 C, what is the specific heat of brass?
0.39 J/g C
In the lab, why was the metal submerged in boiling water?
This is so that it has an initial temperature is 100C, the same as boiling water.
Which material would you use to heat up your food on a stove and why?
Aluminum 0.900 J/g C
Brass 0.380 J/g C
Copper 0.387 J/g C
Steel 0.120 J/g C
Steel. Lowest Specific heat. It can absorb and transfer energy fast.
A 2000. g piece of lead is heated from 80.00 to 100.00 Celcius using 5120 J of energy. The specific heat capacity of lead is _______________.
0.1249 J/g C
A 75.0-gram piece of metal is heated to 100.0∘C and then placed into a cup containing 50.0 g of water at 22.0∘C. If the final temperature of the metal and water mixture is 28.8∘C, what is the specific heat of the unknown metal?
0.266 J/g∘C
Why is it important to quickly transfer the metal into the calorimeter and how would that impact the specific heat?
to prevent loss of heat to the environment; if there is loss of heat, Qwater < Qmetal, which means specific heat (C) will be lower.