Chapter 5 - Energetics and Thermochemistry

What are standard conditions for energy change?

• Pressure of 100 kPa and temperature of 298 K

• All solutions are 1 mol/dm³

• All substances are in the solid state

• All substances are in the gaseous state

What energy changes occur when chemical bonds are formed and broken?

• Energy is absorbed when bonds are formed and when they are broken

• Energy is released when bonds are formed and when they are broken

• Energy is absorbed when bonds are formed and released when they are broken

• Energy is released when bonds formed and absorbed when they are broken

Calculations for the enthalpy of a reaction based on bond enthalpies may be off because: (Choose two)

• Substances are not in the aqueous state

• It's not a gaseous reaction

• They may not take into account intermolecular forces

• They may not take into account intramolecular forces

Which combination is correct for a chemical reaction that absorbs heat from the surroundings?

• Exothermic, Positive ΔH

• Exothermic, Negative ΔH

• Endothermic, Positive ΔH

• Endothermic, Negative ΔH

According to the enthalpy level diagram, what is the sign for ΔH and what is this type of reaction called?

• ΔH positive, exothermic

• ΔH negative, exothermic

• ΔH positive, endothermic

• ΔH negative, endothermic

Which metal will show the greatest increase in temperature if 50 J of energy were added to it?

• Aluminum

• Nickel

• Copper

• Gold

Which statement is correct for the reaction shown?

• 564 kJ of energy is released for every mole of CO reacted

• 564 kJ of energy is absorbed for every mole of CO reacted

• 282 kJ of energy is released for every mole of CO reacted

• 282 kJ of energy is absorbed for every mole of CO reacted

A sample of iron receives 50.J of heat energy that raises the temperature of the iron by 25.0°C. If iron has a specific heat of 0.10 J/g°C, what is the mass of the iron sample?  (show your work)

• 25g
• 30g
• 20g
• 50g

Tags

NGSS.HS-PS3-1

If the specific heat of water is 4.18 J/g∙°C, how much heat is required to increase the temperature of 1.2 kg of water from 23 °C to 39 °C? (show your work)

• -80,256 J

• 80.256 J

• 80,256 J

• -80.256 J

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

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. Is the reaction endothermic or exothermic?

• Exothermic
• Endothermic

Tags

NGSS.HS-PS1-4