Conceptual Questions
What is thermochemistry?
study of the heat changes that occur during chemical reactions
What is the law for the conservation of energy?
Energy cannot be created nor destroyed
The temperature of a 117g piece of brass increases from 13°C to 85°C. How much heat energy was absorbed by the brass?
(Specfic heat of brass is 0.380 J/g°C)
3201.12 Joules
The temperature of a 200g piece of iron increases from 25°C to 40°C. How much heat energy was absorbed by the iron?
1350 J
What was Ms. Rainey's favorite subject in school?
Science! (duh.)
What is heat AND how does it flow?
Heat is a form of energy that always flows from a warmer object to a cooler object.
What is the formula for heat?
Q = m ΔT Cp
A glass of water that is 639g is cooled from 26.4°C to 3.2°C. How much heat energy was released?
(Specific heat of water is 4.18 J/g°C)
-61967 Joules
A balloon containing 500g of air is heated from 0.0°C to 25°C. How much heat energy was required to do this?
12625 J
When is Ms Rainey's birthday?
May 5th
You are sitting outside drinking a cup of tea, thinking about how your body digests the tea. If that is your focus, what is the system? What are the surroundings?
System: Your body and the tea
Surroundings: everything else
Mrs. O’Brien did a reaction in the lab, and she observed that when she touched the glass, it was cold. Which way did heat flow?
Heat flowed from Mrs. O'Brien's hand to the glass
If 2014 J of thermal energy is added to a 358g bowl of NaCl, how much will the temperature rise?
(Specific heat of NaCl is 0.864 J/g°C)
6.511°C
If 1000 J of thermal energy is added to a 500g piece of aluminum, how much will the temperature rise?
2.22°C
What sport did Ms. Rainey play in college?
Swimming!
What is an exothermic reaction?
A process that loses heat to the surroundings
In calorimetry problems, why are we able to set the two equations equal to each other?
(Hint: think about where the heat is being absorbed and released from)
How much will the temperature rise for a 72g sample of copper if 259 J of energy is added?
(Specific heat of copper is 0.385 J/g°C)
9.34°C
If 450 J of thermal energy is added to a 30g sample of mercury at 20°C, what will the final temperature be?
127.14°C
What is Ms. Rainey's favorite color?
Blue
What is an endothermic reaction?
A process that absorbs heat from the surroundings
What is the definition of specific heat capacity?
The amount of energy it takes to increase 1 gram of a substance 1 degree Celcius.
In a coffee-cup calorimeter, an unknown metal was placed into 100.0 g of H2O. The metal had an initial temperature of 23.5 °C, and the water was originally at 65.9 °C. After the reaction, the temperature of both substances is 31.3 °C. The mass of the metal was 6.34 g. If the specific heat of water is 4.18 J/g°C, what is the specific heat of the metal?
292.5 J/g°C
In a coffee-cup calorimeter, an unknown metal was placed into 100.0 g of H2O. The metal had an initial temperature of 44.6 °C, and the water was originally at 24.6 °C. After the reaction, the temperature of both substances is 31.3 °C. The mass of the metal was 6.34 g. What is the specific heat of the metal?
mwater ∆Twater Cpwater = mmetal ∆Tmetal Cpmetal
33.21 J/g°C
What bachelor's degree does Ms. Rainey hold?
(This is from college.)
Neurobiology, Physiology, and Behavior
(Neurobiology is acceptable)