Energy of Chemical Reactions

Which event indicates an endothermic chemical reaction?

• Decrease in temperature

• Release of heat

• Production of light

• Increase in thermal energy

Tags

NGSS.HS-PS1-4

Which statement is true about the reaction shown by this chemical equation?

HCl + NaOH → NaCl + H₂O

• It is endothermic.

• It is exothermic.

• It is a combustion reaction.

• It is a synthesis reaction.

Tags

NGSS.HS-PS1-4

Which type of reaction is represented by this graph?

• Exothermic

• Decomposition

• Endothermic

• Synthesis

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NGSS.HS-PS1-4

Which bonds form in the reaction shown in the diagram?

• The bonds between the two hydrogen atoms

• The bonds between the oxygen and hydrogen atoms

• The bonds between the two oxygen atoms

• The bonds between the two hydrogen atoms and between the two oxygen atoms

This chemical equation represents one of the reactions that form acid rain. Which two options list the bonds that break in the reaction?

• The bonds between N and O in NO₂

• The bonds between H and O in H₂O

• The bonds between N and O and between H and O in HNO₃

• The bonds between N and O and between H and O in HNO₂

Which part of this chemical process requires energy?

NaOH + HCl → NaCl + H₂O

• Breaking bonds in NaCl and H₂O

• Forming bonds in NaOH and HCl

• Forming bonds in NaCl and H₂O

• Breaking bonds in NaOH and HCl

Tags

NGSS.HS-PS1-4

The energy diagram shows the changes in energy during a chemical reaction. Which statement best describes the total energy change of the system?

• The reactants have higher potential energy, and energy is absorbed.

• The reactants have higher potential energy, and energy is released.

• The products have higher potential energy, and energy is released.

• The products have higher potential energy, and energy is absorbed.

Tags

NGSS.HS-PS1-4

How do collisions between molecules transfer energy from a system of reacting substances to its surroundings?

• They cause molecules to flow into the system from the surroundings.

• They cause the thermal energy of the surroundings to decrease.

• They cause heat to flow from the system to the surroundings.

• They cause the potential energy of the system to increase.

Tags

NGSS.HS-PS3-4

Based on the diagram, which statement explains how energy is conserved during this chemical reaction?

• The potential energy lost by the reaction system (C) is also lost by the surroundings.

• The potential energy lost by the reaction system (B) is gained by the surroundings.

• The potential energy gained by the reaction system (A) is also gained by the surroundings.

• The potential energy changes indicated by C and B involve energy lost by the surroundings.

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NGSS.HS-PS1-4

The bonds of the products store 27 kJ more energy than the bonds of the reactants. How is energy conserved during this reaction?

• The reaction system absorbs 27 kJ of energy from the surroundings.

• The reaction creates 27 kJ of energy when bonds form.

• The reaction uses up 27 kJ of energy when bonds break.

• The surroundings absorb 27 kJ of energy from the reaction system.

Tags

NGSS.HS-PS1-4