Thermo Review!

Thermo Review!

By Karina Farias

Fill in the Blanks

An exothermic reaction _ heat.

Fill in the Blanks

A sample of gold weighs 6.5 g and has a specific heat of .128 J/g C. If the temperature lowers 15 C, how much heat is released?

$Q\ =\ mc_p\Delta T$  

Multiple Choice

A hot piece of metal is placed into cooler water. Which statement describes how the second law of thermodynamics relates to this process?

• The temperature change of the metal is equal to the temperature change of the water.

• The amount of energy lost by the metal is equal to the amount of energy gained by the water.

• Energy flows from the metal to the water until they are at the same temperature.

• Energy flows from the water to the metal until they are at the same temperature.

• Release heat

• Raise the temperature of the surroundings

• - ΔH

Fire releases heat to the surroundings.

Exothermic Reactions

• Absorb heat

• Lower the temperature of the surroundings

• + ΔH

​

Ice pack absorbs the heat from your injury.

​Endothermic Reactions

Multiple Choice

In an exothermic reaction, heat is ...

• taken in
• given out

Multiple Choice

A reaction is performed in a beaker with a temperature probe recording the temperature changes of the reaction.  If the temperature began at 15.0 degrees Celsius and ended at 27.5 degrees Celsius.  If the reaction is our system, is the system endothermic or exothermic?

• Exothermic
• Endothermic

Multiple Choice

In an endothermic reaction, heat is ,,,

• taken in
• given out

Multiple Choice

The amount of heat energy required to change the temperature of 12 g of gold from 45°C to 15°C is -47 J. What is the specific heat capacity of gold?

• 0.13 J/(g°C)

• 17,000 J/(g°C)

• 1600 J/(g°C)

• 0.065 J/(g°C)

Q = heat

m = mass

c_p = specific heat

Δ​T = change in temperature

​Q = mc_pΔT

​-Q =

​

+Q =

​

Determining Endo Or Exo​

Calculating Heat

Some text here about the topic of discussion

Multiple Choice

The equation for heat transfer is $$\Delta Q\ =\ m\times c\times\Delta T$$  What is represented by  $$\Delta Q$$  ?

• heat, measured in calories

• mass, measured in grams

• specific heat, in calories/gram/degree C

• temperature change in degree C

Multiple Choice

The equation for heat transfer is $$\Delta Q\ =\ m\times c\times\Delta T$$  What is represented by  $$\Delta T$$  ?

• heat, measured in calories

• mass, measured in grams

• specific heat, in calories/gram/degree C

• temperature change in degree C

Multiple Choice

The equation for heat transfer is $$\Delta Q\ =\ m\times c\times\Delta T$$  What is represented by  $$m$$  ?

• heat, measured in calories

• mass, measured in grams

• specific heat, in calories/gram/degree C

• temperature change in degree C

Multiple Choice

The equation for heat transfer is $$\Delta Q\ =\ m\times c\times\Delta T$$  What is represented by  $$c$$  ?

• heat, measured in calories

• mass, measured in grams

• specific heat, in calories/gram/degree C

• temperature change in degree C

Multiple Choice

If 5.00 grams of water is cooled from 65.2 °C to 35.6 °C, what is the heat change?

• 619 J
• -619 J
• 148 J
• -148 J

Multiple Choice

A 5.00 gram sample of a metal at 85.0 °C comes in contact with 100.0 grams of water at 25.0 °C.  What is the direction of the heat flow and why?

• Metal to water, since heat flows from low mass to high mass
• Water to metal, since heat flows from high mass to low mass
• Metal to water, since heat flows from high temp. to low temp.
• Water to metal, since heat flows from low temp. to high temp.

Multiple Choice

Something that has a low specific heat capacity is likely to:

• stay at close to a constant temperature

• heat up easily and stay hot

• cool down easily and stay cold

• heat up and cool down easily

Multiple Choice

The equation for heat transfer is $$\Delta Q\ =\ m\times c\times\Delta T$$  Using this equation, figure out how much heat is required to warm up 2000 g of water from 20 degree C to 100 degrees C. Conveniently, the specific heat capacity of water is 1 cal/gram/degree C

• 40,000 cal

• 160,000 cal

• 20,000 cal

• 80,000 cal

Multiple Choice

The equation for heat transfer is $$\Delta Q\ =\ m\times c\times\Delta T$$  Using this equation, figure out how much heat is released when 100 grams of olive oil cool by 40 degrees C. The specific heat capacity of olive oil is c = 0.5 calories/gram/degree C.

• 40 cal

• 100 cal

• 1000 cal

• 2000 cal

Multiple Choice

The part of the world that we study in a chemical reaction is called the 

• universe
• surroundings
• system
• ecosystem

Multiple Choice

Heat always flows from _____ to ________

• cold to hot
• hot to cold
• top to bottom
• bottom to top

Multiple Choice

The measure of heat flow into or out of a system due to physical or chemical processes is called

• calorimetry
• temperature
• energy
• specific heat

Multiple Choice

A metal cylinder at 95.6⁰C was placed in a cup of water at 22.0⁰C. After 3 minutes the final temperature was 26.8⁰C. How did heat energy flow?

• from the metal to the cup
• from the water to the metal
• from the metal to the water
• heat did not flow

Multiple Choice

The energy required to raise 1 g of a substance by 1°C is called _____

• specific heat
• thermal energy
• heat of reaction
• temperature

Multiple Choice

Of the following substances, which has the highest specific heat? 

• Water
• Aluminum
• Copper
• Zinc

Multiple Choice

If a 40.0 g sample of metal cools from  80.0°C to 20.0°C and loses 1060 J of energy, what is the specific heat of the metal?   
C=q/mΔT

• -0.442 J/g°C
•  0.442 J/g°C
• 0.00142 J/g°C
• 0.000629 J/g°C 

Multiple Choice

The specific heat of silver is 0.24 J/g·°C. How many joules of heat must be added to an  83.6 g silver block to raise its temperature by 9.0°C?
q=mCΔT

• 0.00032 J
• 0.45 J
• 180 J
• 39 J

Multiple Choice

If a chemical reaction is EXOTHERMIC, the temperature would....

• Stay the same
• Increase
• Decrease

Multiple Choice

Is the combustion of gasoline endothermic or exothermic?

• Endothermic
• Exothermic

Multiple Choice

Is photosynthesis an exothermic or endothermic reaction?

• Endothermic
• Exothermic

Multiple Choice

Baking bread and cooking an egg are examples of....?

• Endothermic processes
• Exothermic processess
• None of these 

Multiple Choice

What is true of the reaction described below?
Br₂ + Cl₂ + 30.0 J of energy  → 2BrCl

• It is exothermic because energy was released.
• It is endothermic because energy is absorbed.
• It is exothermic because energy is absorbed.
• It is endothermic because energy is released.

Multiple Choice

What kind of reaction is this? The energy readings are top 103, middle 45 and bottom 10

• Endothermic

• Exothermic

• Cannot be determined