Thermochemistry

During an exothermic reaction, heat content in the surroundings increases because

• heat energy is destroyed during reactions

• the reaction absorbs heat energy

• the energy contained in the reactants is lower then the products

• the energy contained in the products is lower than the reactants

The diagram represents two solids and the temperature of each. What occurs when the two solids are placed in contact with each other?

• Heat energy flows from solid A to solid B. Solid A decreases in temperature

• Heat energy flows from solid A to solid B. Solid A increases in temperature

• Heat energy flows from solid B to solid A. Solid B decreases in temperature.

• Heat energy flows from solid B to solid A. Solid B increases in temperature.

When methane, CH4, and oxygen, O2, are mixed in a stove and ignited, a lovely blue flame results. The balanced equation is: CH₄(g) + 2O₂(g) 2H₂O(g) + CO₂(g) What can be said about the energy involved in this chemical reaction?

I. The average kinetic energy of the products is greater than that of the reactants.

II. The chemical energy stored in the reactants is greater than the chemical energy stored in the products.

III. Chemical energy in the reactants is changed into heat energy and light energy.

• I only

• II only

• III only

• I, II, and III

In an endothermic reaction the system is releasing energy.

• True
• False

Tags

NGSS.HS-PS1-4

In an exothermic process the surrounding looses heat. 

• True
• False

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

Is the combustion of gasoline endothermic or exothermic?

• Endothermic
• Exothermic

Tags

NGSS.HS-PS1-4

As someone is running on the track they begin to perspire.  If the runner is our system, are they endothermic or exothermic?

• Endothermic process
• Exothermic process

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

Tags

NGSS.HS-PS1-5

NGSS.HS-PS3-4

Which of the following is an endothermic process?

• solid to gas
• liquid to solid
• solid to liquid
• gas to liquid

Thermochemistry is

• the study of heat changes when physical reactions occur.

• the study of heat changes when chemical reactions occur.

• the study of energy changes when chemical reactions occur.