Acids, Bases and Kw

Question 1

What are Brønsted-Lowry acids?

Answer 1

They are proton donors and release H+ ions when they’re mixed with water

Question 2

What are Brønsted-Lowry bases?

Answer 2

They are proton acceptors ; when in solution they grab hydrogen ions from water molecules

Question 3

Strong acids and strong bases… in water

Answer 3

Dissociate fully or almost completely

Question 4

Weak acids and weak bases…in water

Answer 4

Only very slightly dissociate/ionise in water so small numbers of H+ ions are formed. An equilibrium is set up which lies well over to the left

Question 5

Write an equation for the donation of a proton from an acid to a base

Answer 5

HA + B ->

Question 6

Write an equation for when an acid is added to water

Answer 6

HA + H2O ->

Question 7

What does water dissociate into?

Answer 7

Hydroxonium ions and hydroxide ions

Question 8

Why is the concentration of water considered to have a constant value?

Answer 8

Because there’s so much water compared to H+ and OH- ions

Question 9

What are the units for Kw?

Answer 9

Mol2 dm-6

Question 10

What is the expression for Kw?

Answer 10

Kw= [H+][OH-]

Question 11

If you’re dealing with pure water, what can the expression for Kw be shortened to?

Answer 11

Kw= [H+]2

Question 12

At 298K, what value does Kw have?

Answer 12

1.00 x 10-14 mol2 dm-6