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Gizmos Student Exploration: Reaction Energy Answer Key
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Gizmos Student Exploration: Reaction Energy Answer Key
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Name: Date:Student Exploration: Reaction Energy
Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the
orange boxes.
Vocabulary: calorimeter, chemical bond, endothermic, enthalpy, exothermic, Hess’s law
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. Two magnets are stuck together. What might you have to do to get them to separate?
Pull them apart.
2. Suppose you held two magnets a short distance apart, then let go. What would happen?
They would connect.
3. Think about the magnets in terms of energy. In which case do you increase the potential energy of the magnets?
In which case do you increase the kinetic energy of the magnets?
The farther apart the magnets are the higher increase the potential energy has, while the
magnets move towards each other the kinetic energy increases.
Gizmo Warm-up
Just like magnets, atoms of different elements are attracted
together to form chemical bonds. Breaking these bonds
requires energy. When a new bond forms, energy is released and
temperatures rise. In the ReactionEnergy Gizmo, you will
explore how the energy of chemical bonding relates to
temperature changes that occur during chemical reactions.
To begin, check that Reaction 1 and Forward are selected. In this reaction, hydrogen (H2) and oxygen (O2) react to form
water (H2O). The reaction takes place inside a device called a calorimeter. Inside the calorimeter, a small chamber holds
the reactants. The rest of the calorimeter is filled with water.
1. Click Play ( ). What happens?
The H2 and O2 came together to form H2O
2. How does the temperature change?
The temperature has increased from 21.0 C to 27.4 C
Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
, Activity A: Get the Gizmo ready:
Energy of ● Check that Reaction 1 and Forward are selected.
chemical bonds ● Select the INVESTIGATION tab.
Introduction: The heat energy stored in a chemical system is called the enthalpy (H) of the system. When atoms are
joined by a chemical bond, energy must be added to pull them apart. This increases the enthalpy of the system. When a
chemical bond forms, energy is released as shared electrons move into lower-energy orbitals. This causes the enthalpy to
decrease.
Question: How can you predict how much energy is released in a chemical reaction?
1. Predict: In the warm-up activity, you observed how the reaction inside the chamber affected the temperature of the
surrounding water. Based on what happens to the surrounding water, do you think heat energy (enthalpy) is absorbed
in the reaction or released? Explain.
I think the enthalpy was released during the reaction because of the energy release that
shares electrons moving into lower-energy orbitals.
2. Observe: In the Gizmo, the energy required to break a chemical bond is modeled by placing a molecule into a set
of mechanical claws. Place one of the hydrogen (H2) molecules between the claws, and press Break bond.
A. What happens?
It breaks in half
B. Look under the Energy absorbed column of the table. How much energy was required to break thisbond?
436 kJ/mol
Note: The energy is given here in units of kilojoules per mole (kJ/mol). This is the energy, in kilojoules,
required to break all of the H–H bonds in one mole of H2 gas.
C. Remove the hydrogen atoms from the claws and then break apart the other H–H molecule.
What is the total energy absorbed so far? 872 kJ/mol
3. Measure: Notice that the oxygen atoms are connected by a double covalent bond. This is because the oxygen
atoms share two pairs of electrons. Place the oxygen molecule in the claws and press Break bond.
A. How much energy is required to break the first O–O bond? 349 kJ/mol
B. Press Break bond. How much energy is needed to break bothbonds? 495 kJ/mol
Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
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