(Chapter 4.1) Using Chemistry: Chemical Reactions and Energy Flashcards
What is an exothermic reaction?
An exothermic reaction is a reaction that produces energy
What is an endothermic reaction?
An endothermic reaction is a reaction that absorbs energy
True or False. Exothermic reactions always release heat (energy).
False. While it is usually heat energy, the energy can be released as electrical, light or some other form.
In an exothermic reaction, does the reactants or products have more stored energy?
Reactants
In an endothermic reaction, does the reactants or products have more stored energy?
Products
Do reactions that break bonds tend to be exothermic or endothermic and why?
It is usually an endothermic reaction as breaking chemical bonds requires a significant amount of energy and endothermic reactions absorb energy.
Do reactions that form bonds tend to be exothermic or endothermic and why?
It is usually an exothermic reaction as forming bonds requires no energy. The total energy of bonded atoms is lower than those atoms individually and the excess energy is released.
True or False. Every collision between reactants results in a chemical reaction.
False. The particles must collide with enough energy.
Define activation energy
The minimum energy necessary for a chemical reaction to occur
In what units is activation energy measured in?
Joules(J) or kilojoules (kJ)
Is the activation energy higher in A –> B or B –> A given that A –> B is an exothermic reaction and why?
B –> A as endothermic reactions require a higher activation energy as it has a net gain in energy.
Using letters as substitution for the anion and cation in the compounds, illustrate a synthesis reaction
A+B –> AB
Are synthesis reactions usually exothermic or endothermic?
Exothermic as bonds are formed
Are decomposition reactions usually exothermic or endothermic?
Endothermic as bonds are broken
What is thermal decomposition?
A decomposition reaction that uses heat to supply energy for the reaction
What is the difference between electrolytic decomposition and electrolysis?
There is no difference
What is electrolytic decomposition?
A decomposition reaction that uses electricity to supply energy for the reaction
Define electrochemical cell
A device that can generate electrical energy from the chemical reactions occurring in it or use the electrical energy supplied to it to facilitate chemical reactions
What is the name of the electrochemical cell produces energy?
Voltaic or galvanic cell
What is the name of the electrochemical cell that uses energy?
Electrolytic cell
Name the components of an electrochemical cell
Electrode, liquid electrolyte, dissolved ionic substance, and a porous membrane
What is the ‘informal’ term for a porous membrane?
A ‘salt-bridge’
Define electrolyte
A medium that contains ions that can conduct electricity
Define electrode
An electrical conductor that makes contact with the nonmetallic circuit parts of a circuit. (It is also a pokemon lol)
Define half-cell
1 of the 2 an electrochemical cell containing an electrode and an electrolyte
Define anode
An electrode with a negative charge
Define cathode
An electrode with a positive charge
What is the role of the electrodes in an electrochemical cell?
The role of electrodes is to transfer/move the cations (positive ions). This occurs through the release or absorption of cations by the electrodes in order to become stable
What is the role of the liquid electrolyte in an electrochemical cell?
The role of the liquid electrolyte is to provide a medium that enables movement of the cations
What is the role of the dissolved ionic substance?
The role of the dissolved ionic substance is to facilitate the release and absorption of cations
What is the role of the porous membrane?
The role of the porous membrane is to enable the movement of the cation between the 2 half-cells
What causes an electric current in an electrochemical cell?
The movement of cations results in the movement of electrons in the opposite direction
When does electricity stop flowing in an electrochemical cell?
It stops flowing when a half-cell runs out of substances necessary for its reaction
Define by-product
A substance produced as a direct result of the desired reaction
Is sponge cake a suitable electrochemical cell and why?
Not suitable. Electrochemical cells require an electrode and electrolyte and as sponge cake has no juice/liquid electrolyte
