Equilibrium and Ka Calculations

The video tutorial explains how to calculate the acid dissociation constant (Ka) of nitrous acid (HNO2) using its pH value. It begins with an introduction to the problem, followed by setting up the acid-base equilibrium and writing the Ka expression. The tutorial then demonstrates the use of the ICE box method to determine equilibrium concentrations. Finally, it shows how to use the given pH to find the hydronium concentration and calculate the Ka value, emphasizing the stoichiometric relationships and arithmetic involved.

What is the initial concentration of the HNO2 solution used in the calculations?

• 0.0345 M

• 0.0516 M

• 0.0234 M

• 0.0678 M

Which species are involved in the equilibrium expression for the reaction of nitrous acid with water?

• Nitrous acid and hydronium

• Nitrous acid and water

• Hydronium and nitrite ions

• Water and nitrite ions

Why is water not included in the Ka expression for the reaction?

• Because it is a gas

• Because it is a pure liquid

• Because it is a solid

• Because it is an aqueous species

What is the stoichiometric ratio of nitrous acid to hydronium in the reaction?

• 2:2

• 1:1

• 2:1

• 1:2

What is the change in concentration for the nitrous acid in the ICE box setup?

• -X

• 0

• -2X

• +X

How is the hydronium concentration at equilibrium determined from the pH?

• By subtracting the pH from 10

• By adding 10 to the pH

• By taking 10 to the power of the negative pH

• By multiplying the pH by 10

What is the equilibrium concentration of hydronium ions if the pH is 2.34?

• 0.46 M

• 0.046 M

• 0.00046 M

• 0.0046 M

What is the equilibrium concentration of nitrite ions in the solution?

• 0.0046 M

• 0.46 M

• 0.046 M

• 0.00046 M

How is the Ka value calculated from the equilibrium concentrations?

• By subtracting the concentration of nitrous acid from the sum of hydronium and nitrite concentrations

• By dividing the concentration of nitrous acid by the product of hydronium and nitrite concentrations

• By adding the concentrations of all species

• By multiplying the concentrations of hydronium and nitrite ions and dividing by the concentration of nitrous acid

What is the calculated Ka value for the nitrous acid solution?

• 4.5 x 10^-5

• 4.5 x 10^-4

• 4.5 x 10^-3

• 4.5 x 10^-6