Chemical and Nuclear Energy

Which statements about exothermic reactions are correct?

I. They have negative ΔH values II. The products have a higher amount of energy released than the reactants had of energy taken III. The products are more energetically stable than the reactants

• I and II only

• I and III only

• II and III only

• I, II, and III

Tags

NGSS.HS-PS1-4

When the solids Ba(OH)₂ and NH₄SCN are mixed, a solution is produced and the temperature drops. Which statement about the energetics of this reaction is correct?

• The reaction is endothermic and ΔH is negative

• The reaction is endothermic and ΔH is positive

• The reaction is exothermic and ΔH is negative

• The reaction is exothermic and ΔH is positive

Tags

NGSS.HS-PS1-4

Using the table of average bond energies below the image, the ΔH for the reaction in kJ is.....

• + 160 kJ
• -63 kJ
• - 160 kJ
• -217 kJ

Tags

NGSS.HS-PS1-4

Is this equation endo- or exo-thermic?

PCl3 (s) + Cl2 (g) --> PCl5 (s) + energy

• endothermic

• exothermic

Tags

NGSS.HS-PS1-4

Is this equation endo- or exo-thermic?

2KNO3 (s) + energy --> 2KNO2 (s) + O2

• endothermic

• exothermic

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

How can we figure out if an overall reaction is endo- or exo-thermic? It is the difference between _______ and __________.

• hot and cold temperatures

• energy to break and energy to form bonds.

• time to form a bond versus time to break a bond

Tags

NGSS.HS-PS1-4

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

• Stay the same

• Increase

• Decrease

Tags

NGSS.HS-PS1-4

When iron nails get rusty, heat is released.  What process is this?

• Exothermic

• Endothermic

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

During an endothermic reaction in a beaker if we are part of the surroundings and touched the beaker, it would feel _______. 

• warm

• cold

• room temperature

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

The Law of conservation of energy states that

• energy can be created or destroyed

• energy cannot be created or destroyed

• energy can be potential or kinetic only

• heat energy is kinetic energy