Exothermic and Endothermic Diagrams

In an experiment, solid barium hydroxide and solid ammonium chloride are mixed together, and the temperature of the resulting mixture is measured. After some time, the formation of a liquid is observed, and the smell of ammonia gas is detected. A graph of temperature against time for the first 200 seconds of the reaction is shown below. Is the reaction exothermic or endothermic?

• This cannot be determined.

• Endothermic

• Exothermic

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

Illustrated in the reaction profiles are the changes in chemical energy during a range of processes. Which of the diagrams best describes the changes in chemical energy for a stick of dynamite during an explosion?

• a

• b

• c

Tags

NGSS.HS-PS1-4

A reaction profile diagram for a reaction is shown. How much is energy is absorbed or released?

Tags

NGSS.HS-PS1-4

Which diagram represents the reaction whose Δ𝐻 is −20kJ?

• a

• b

• c

• d

Tags

NGSS.HS-PS1-4

The complete combustion of methanol proceeds according to the equation: (picture). The reaction enthalpy is −715 kJ/mol.Is the combustion of methanol endothermic or exothermic?

• Exothermic

• Endothermic

Tags

NGSS.HS-PS1-4

Illustrated in the reaction profile are the changes in chemical energy during a reaction as the reactant molecules are converted to products. Based on the reaction profile, is energy absorbed or released during the reaction?

• Released

• More information is needed.

• Absorbed

Tags

NGSS.HS-PS1-4

Which of these diagrams represents an EXOTHERMIC reaction?

• Diagram A

• Diagram B

Tags

NGSS.HS-PS1-4

This is an example of an...

• Exothermic chemical reaction

• Endothermic chemical reaction

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

The bag you made in class that felt cold afterwards was an example of an...

• Exothermic chemical reaction

• Endothermic chemical reaction

Tags

NGSS.MS-PS1-4

Which of the following diagrams represents an exothermic reaction?

• A diagram where the products have lower energy than the reactants

• A diagram where the products have higher energy than the reactants

• A diagram with a flat energy line

• A diagram with a zigzag energy line

Tags

NGSS.HS-PS1-4