Introduction to Thermochemistry

Thermochemistry Run-Down!

Grab a chromebook and log in!!! Have a sheet of paper with you for notes! EXAM ON MONDAY.

By Ms. Rodriguez

Poll

How well do you know how to solve for specific heat, q?

• not at all

• about 70%

• I fully understand it

• I need more practice but I'm getting there.

Multiple Choice

If kinetic energy increases what will happen?

• lower temperature

• higher temperature

• heat will be released

• nothing will happen

​ΔH = +34 J, ENDOthermic

​

​​ΔH = -34 J, EXOthermic

​

Enthalpy, ΔH

Replace this with a header

Some text here about the topic of discussion

​What would the following examples be?​

1. ​ΔH = +40 J

2. ΔH = +807 J

3. ΔH = -340 J​

Multiple Choice

Which enthalpy ( $$\Delta H$$  ) shows an EXOthermic reaction?

• $$\Delta$$ H= +34 J 

• $$\Delta$$ H= +2,070 J

• $$\Delta$$ H= -547 kJ

• $$\Delta$$ H= +4,223 kJ

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)

Multiple Choice

An iron skillet is used to fry bacon. The pan must be heated to about 178 ^oC from a room temp of 22.0 ^oC. About 158,000 J of heat energy are absorbed by the pan to reach the desired temp. The specific heat of iron is 0.450 J/g ^oC. What must the mass of the skillet be?

• 1,270 g

• 2,250 g

• 110 g

• 1,097 kg

Multiple Choice

Experimental Set-up for Calories in a Chocolate Chip Cookie Students designed an experiment to determine the amount of calories in a chocolate chip cookie. A ring stand was used with a clean aluminum soda can hung from the ring that was partially filled with a known mass of water. A thermometer was placed inside the can so that it measured the temperature of the water but did not touch any part of the metal can. Once set-up was complete, an initial water temperature was taken. The cookie was then lit on fire and allowed to completely burn. A final temperature of the water was measured.

Refer to the experimental set-up for calories in a chocolate chip cookie. How does this experiment allow students to measure the calories in a cookie?

• The difference in masses before and after the cookie is burned is calculated, then converted into heat energy.

• Heat energy from the burning cookie is transferred to the water. The change in water temperature is used to calculate the heat energy from the cookie.

• Data from the amount of time for the cookie to burn and the temperature change are used to calculate the heat energy from the cookie.

• The cookie is burned until the water reaches a boiling temperature, then masses are compared to calculate the heat energy from the cookie.

Multiple Choice

In an exothermic process the surrounding looses heat. 

• True
• False

Multiple Choice

In an endothermic reaction the system is releasing energy.

• True
• False

Multiple Choice

ΔH value in an endothermic reaction is a positive number.

• True
• False

Multiple Choice

The unit Joules is for ___________

• heat energy
• temperature
• specific heat

Multiple Choice

The potential energy diagram of a reaction is shown. Which statement below is correct relating to this reaction?

• #1 represents the enthalpy change for this exothermic reaction.

• #2 represents the enthalpy change for this endothermic reaction.

• #3 represents the enthalpy change for this endothermic reaction.

• #4 represents the enthalpy change for this exothermic reaction.

Poll

How well do you know how to solve for specific heat, q?

• not at all

• about 50%

• I fully understand it

• I need more practice but I'm getting there.