Module 15 Flashcards
What is the definition of chemical equilibrium?
Chemical equilibrium is the point at which the rate of the forward reaction equals the rate of the reverse reaction
Does a chemical reaction actually stop once equilibrium?
Chemical reactions never stop, even when equilibrium is reached
A chemist is studying 2 chemical equilibria. Reaction A has an equilibrium constant equal to 1,213 M, while Reaction B has an equilibrium constant equal to 0.344 M squared. Which reaction will make more products?
the first (reaction A). (larger equilibrium more weighted towards product)
After taking a cursory glance though a chemistry book. a student says that sometimes a chemical reaction is written with a single arrow and sometimes it is written with a double arrow. The student says that this means some chemical reactions are equilibrium reactions and some are not. What is wrong with the student’s statement?
Because all reactions are equilibrium reactions. Some are written with one arrow because their constants (ks) are so large that there are virtually no reactants left when the reaction reaches equilibrium.
Why do we ignore solids in the equilibrium constant and when using Le Chatelier’s principle?
because the solid’s concentration stays the same no matter what happens in the chemical reaction.
Why are acid ionization reactions important in chemistry?
because they determine the strength of an acid
What are the limits of the pH scale?
0-14
Three solutions have the following pH levels. Which is (are) the acidic solution(s)? (Chemicals-pH):
A-1, B-10, C-7
A-Yes B-No C-No
Three acid solution of equal concentration have the following pH levels:
A: pH = 1 B: pH = 4 C: pH = 6
Which solution is made with the acid that has the lowest ionization constant?
C (highest pH = weakest acid because lower ionization constant)
Where does acid rain come from?
Acid rain comes from pollutants like sulfur trioxide and nitrogen dioxide that react with water to form acids
What does the equilibrium constant do and what is its sign?
it tells us about how much reactant and how much product exist at equilibrium, it’s sign is K
What is not included in a chemical equilibria equation?
solids and liquids (aqueous and gas phases are included)
What is Le Chatelier’s principle? what does this principle ignore?
When a stress (such as a change in concentration, pressure, or temperature) is applied to an equilibrium, the reaction will shift in a way that relieves the stress and restores equilibrium.
It ignores solids and liquids as a source of stress to the equilibrium
What happens when an equilibrium is subjected to an increase in pressure?
What will happen if that pressure is decreased?
What will happen if there are no gases?
When pressure is increased the equilibrium will shift away from the side with the largest number of gas molecules. If pressure is decreased the equilibrium will shift toward the side with the largest number of gas molecules. If there are no gases nothing will happen
What will happen to an equilibrium when the temperature is changed?
When the temperature is raised an equilibrium will shift away from the side of the equation that contains energy. When temperature is lowered, the reaction will shift towards the side that contains energy
