Thermochemistry

A reaction is performed in a beaker with a temperature probe recording the temperature changes of the surroundings. 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-PS1-4

Refer the the following question:
2N₂ + 3H₂ --> 2NH₃ + 46 kJ
How much energy would be produced if only 1 mol of nitrogen was reacted?

• 92 kJ
• 0.143 kJ
• 23 kJ
• 15 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

How much energy must be used to produce 4.75 mol of gaseous water?

H₂O (l) + 44.0 kJ --> H₂O (g)

• 209 kJ

• 9.26 kJ

• 206 kJ

• 9.36 kJ

Tags

NGSS.HS-PS3-1

In a laboratory experiment a student was using Styrofoam cups and foil to reduce the energy lost during an exothermic reaction.  The reaction constantly had a temperature probe in it.  Towards the end of the reaction the student noticed the temperature in the cups was going down (opposite what they thought is should).  The student concluded that the energy was destroyed within the system.  This student's reasoning violates what law?

• Law of Conservation of Mass
• Law of Enthalpy
• First Law of Thermodynamics
• Law of Heat Transfer

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

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.

Tags

NGSS.HS-PS1-4

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.

Tags

NGSS.HS-PS3-4

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)

Tags

NGSS.HS-PS3-4

The graph represents the uniform heating of a substance, starting with the substance as a solid below its melting point. Which line segment listed below represents an increase in potential energy and no change in average kinetic energy?

• Line segment AB

• Line segment BC

• Line segment CD

• Line segment EF

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-2

A cast iron skillet is used to fry bacon. For optimal frying, the pan must be heated to about 178 ^oC from a room temperature of 22.0 ^oC. It is known that 1.58 x 10⁵ J of heat energy are absorbed by the pan to reach the desired temperature and the specific heat of iron is 0.450 J/g ^oC. What must the mass of the skillet be?

• 12.7 kg

• 2.25 kg

• 110 kg

• 1.97 kg

Tags

NGSS.HS-PS3-1

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

Tags

NGSS.HS-PS1-4