Which of the following mixtures has the highest pH? (a) Equal volumes of 1.0 M HCl and 1.0 M NaOH (b) Equal volumes of 0.1 M HNO3 and 0.1 M KOH (c) Equal volumes of 0.1 M HCN and 0.1 M NaOH (d) Equal volumes of 0.1 M NaF and 0.1 M HCl

Video transcript

Hey everyone were given equal volumes of each mixture component determine which of the following is the most basic, meaning the highest ph so for the first one we have a mixture of 0.125 moller of potassium fluoride and 0.125 molar of hydrochloric acid. So if we write out this reaction, we have potassium fluoride plus hydrodynamic acid. And this will get us to Hydrofluoric acid plus potassium bromide. As we know our flooring ion from potassium fluoride is a weak base and hydrochloric acid is a strong acid. So our flooring ion and our hydrochloric acid will neutralize one another. But since Hydrofluoric acid is formed from the reaction, the weak acid Hydrofluoric acid will impart acidity to the solution. So taking that Hydrofluoric acid and adding this into water, we end up with our flooring ion plus our hydro ni um ion. So this means our ph Will be lower than seven. So be more acidic. Next looking at B We have a mixture of 0.125 molar of Hydrofluoric acid and 0.125 molar of potassium hydroxide. Riding out this reaction, we have Hydrofluoric acid plus potassium hydroxide. When these two react, we get our potassium fluoride plus our water. So Hydrofluoric acid is a weak acid and potassium hydroxide is a strong base. So Hydrofluoric acid and potassium hydroxide will neutralize one another. But if we go ahead and take our potassium fluoride. And we react this with water, we end up with Hydrofluoric acid plus our hydroxide ion. And because of this this will impart basis city to the solution. So our ph Will be greater than seven. Now let's go ahead and look at C for C, we have a mixture of 1.25 molar hydrochloric acid and 1.25 molar potassium hydroxide. Now, if we write out our reaction, we have hydrochloric acid plus potassium hydroxide, this will get us to potassium bromide plus our water. And this is a neutral solution. And the reason why is because hydrochloric acid is a strong acid and potassium hydroxide is a strong base. So we end up with this neutral salt solution. Next looking at D We have a mixture of 0.125 molar of our cleric acid And 0.125 moller of sodium hydroxide. Now, when we write out our reaction, we have cleric acid plus our sodium hydroxide. And this will get us to sodium chlorate plus our water again, this is going to be a neutral solution. And the reason why is because we know that cleric acid is a strong acid and sodium hydroxide is a strong base. So we end up with that neutral salt solution. Now to answer this question, it looks like our answer here is going to be answer choice B a mixture of 0.125 moller Hydrofluoric acid and 0.125 molar potassium hydroxide since we were able to get that ph of greater than seven. So I hope this made sense and let us know if you have any questions.