Reverse reactions Flashcards

1
Q

What is a reversible reaction?

A

Some chemical reaction can proceed in both forwards and backwards directions. We describe these reactions as reversible.

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2
Q

What does a reversible reaction look like?

A

A + B –> C + D

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3
Q

What do the reactants (A+B) combine to make?

A

They combine to give the products (C+D)

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4
Q

What do products (C+D) combine to make?

A

They combine to give the reactants (A+B)

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5
Q

If the forwards reaction (transfers energy from reactants to the environment) what type of reaction would the backwards reaction be?

A

Endothermic (transfers energy from environment to the reactants)

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6
Q

What is conserved during chemical reactions?

A

Energy

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7
Q

What is eventually reached when reversible reactions happen within a closed system?

A

A dynamic equilibrium

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8
Q

What is a closed system?

A

A system where reactants and products can neither be added not removed.

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9
Q

What happens at dynamic equilibrium?

A

The rates of the forwards and backwards reactions are equal.

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10
Q

Why is the equilibrium dynamic?

A

Both the forward and backward reactions are still taking place.

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11
Q

What doesn’t change at dynamic equilibrium?

A

The concentrations of reactants and products.

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12
Q

What do the conditions determine in a reaction as equilibrium?

A

The relative quantities of the different reactants and products

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13
Q

What does Le Chatelier’s principle say?

A

If any of the conditions of a reversible reaction at equilibrium are changed, the closed system will adapt to counteract whatever has changed.

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14
Q

What is Le Chatelier’s principle used to predict?

A

The outcome of changes imposed on a system at equilibrium.

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15
Q

What does changing the conditions in a reversible reaction affect?

A

The position of equilibrium

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16
Q

What does changing the temperature for a reaction at equilibrium do?

A

Takes the system out of equilibrium. The system will react to try and restore the equilibrium.

17
Q

What will decreasing the temperature in a chemical reaction do to the position of equilibrium?

A

The position of equilibrium will shift in the exothermic direction.

  • The amount of products generated by the exothermic reaction will increase.
  • The amount of products generated by the endothermic reaction will decrease.
18
Q

What will increasing the temperature in a chemical reaction do to the position of the equilibrium?

A

The position of equilibrium will shift in the endothermic direction.

  • The amount of products generated by the endothermic reaction will increase.
  • The amount of products generated by the exothermic reaction will decrease.
19
Q

If the forward reaction of a reversible reaction is endothermic, what happens when the temperature is decreased?

A

The backward reaction is favoured.

20
Q

What happens to the position of equilibrium if pressure is increased?

A

The position of equilibrium will shift to favour the reaction that produces the fewest gas molecules.

21
Q

What happens to the position of equilibrium if pressure is decreased?

A

The position of equilibrium will shift towards the side of the reaction that produces the most gas molecules.

22
Q

Pressure changes only affect reactions involving reactants in what state?

A

Gas

23
Q

What will changing the concentration of any reactant or product do to the system?

A

Takes the system out of equilibrium so the system will react to try to restore the equilibrium.

24
Q

What happens when we increase the concentration of a reactant? (to the equilibrium)

A

This will shift the position of equilibrium towards the products.

25
Q

What happens when we increase the concentration of a product?

A

This will shift the position of the equilibrium towards the reactants.

26
Q

What do we need to assess to predict the outcome of pressure change?

A

We must assess balanced equations to see how many gas molecules are on each side of the equation.