In which of these solutions will HNO2 ionize less than it does in pure water? a. 0.10 M NaCl b. 0.10 M KNO3 c. 0.10 M NaOH d. 0.10 M NaNO2

Video transcript

Hey, everyone. And welcome back to another video. In which of these solutions will nitrous acid ionize less than it does in pure water. We're given four answer choices. A 0.7 molar of sodium chloride, B 0.7 molar of potassium nitrate. C 0.7 molar of sodium hydroxide and D 0.7 molar of sodium nitrate. First of all, let's write down the ionization equation. So we have HNO two that's nitrous acid. In order for it to ionize, it must react with water. And therefore, we have a proton transfer. We have an equilibrium reaction where we are producing H 30 plus which is hydro and nitrite, right. No two minus. If we want to ionize it less than it does in pure water. This means that according to the principle of Lucia, we want to shift the equilibrium to the left towards the formation of the reactants instead of products. And we can do that by utilizing the common iron effect, which essentially allows us to do so. If we initially have at least one of the ions on the right hand side, then we are able to shift the equilibrium to the left. So looking at the substances that we have starting with a sodium chloride associates in a solution into sodium cations and chloride anions. And none of these ions corresponds to the iron on the right hand side. Right. So it has no effect, we can essentially neglect the ionic strength and say that roughly there would be no effect to the degree of ionization. Now, b we have pedestrian nitrate which dissociates into potassium cation ions and nitrate nitrate anions. And once again, none of them correspond to the ions on the right. C sodium hydroxide associates the sodium CS and hydroxide anions. And actually hydroxide would react with hydro to produce water. So it would essentially neutralize the acid and it would drive the reaction forward instead of in a reverse direction, right. So it's the opposite effect that would actually increase the degree of ionization by essentially removing hydro from the solution. And D should be the right answer, right? Because this is our final option. We have once again, sodium ions and nitrite anions, which indeed tells us that we now have a common ion. Now, essentially this means that initially, if we add sodium nitrate, it would allow us to shift the equilibrium to the left and not allow for H 102 to ionize that much due to the initial amount of nitride. Therefore, we can conclude that the correct answer to this problem would be option D zero point, some molar of sodium nitrate is the substance. Or actually, in this case, the solution that would make nitrous acid ionized less than it does in pure water due to the common iron effect. Thank you for watching.