Enthalpy of Reaction

Is this equation endo- or exo-thermic?

• endothermic

• exothermic

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Is this equation endo- or exo-thermic?

2KNO₃ (s) + energy --> 2KNO₂ (s) + O₂

• endothermic

• exothermic

Tags

NGSS.HS-PS1-4

When new chemical bonds form, energy ____________.

• is taken into the system.

• is released from the system.

• stays the same in the system.

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-PS3-1

NGSS.HS-PS3-4

Which statement describes characteristics of an endothermic reaction?

• The sign of △H is positive and the products have less potential energy then the reactants

• The sign of △H is negative, and the products have less potential energy than the reactants

• The sign of △H is positive and the products have more potential energy then the reactants

• The sign of △H is positive, and the products have more potential energy than the reactants

Tags

NGSS.HS-PS1-4

Which tendencies favor a spontaneous reaction?

• decreasing enthalpy and decreasing entropy

• increasing enthalpy and increasing entropy

• increasing enthalpy, and decreasing entropy

• decreasing enthalpy and increasing entropy

Which phrase best describe the following reaction 2H₂ + O₂ --> H₂O + energy?

• endothermic, absorbing energy

• endothermic, releasing energy

• exothermic, releasing energy

• exothermic, absorbing energy

Tags

NGSS.HS-PS1-4

Based on the equation △G = △H - T△S, a chemical reaction will most likely occur spontaneously if

• △H is + and △S is +

• △H is - and △S is +

• △H is - and △S is -

• △H is + and △S is -

Which of the following statements is true about the enthalpy of reaction?

• Enthalpy change is always positive for exothermic reactions.

• Enthalpy change is always negative for endothermic reactions.

• Enthalpy change can be either positive or negative depending on the reaction.

• Enthalpy change is zero for all chemical reactions.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

In an exothermic reaction, what happens to the enthalpy of the system?

• It increases.

• It decreases.

• It remains constant.

• It becomes zero.

Tags

NGSS.HS-PS1-4