Weak/Strong Acid and base

[BeauBrown]

For the midterm, how am I supposed to calculate if a salt is acidic/basic from only molar concentrations?

[705960571]

First you should determine whether the ions in the salt will contribute acidically or basically to the solution they are in. For instance Na is neutral and does not influence the pH but many conjugate bases of weak acids are basic and do influence the pH. From there if one of the ions for instance is basic then you can write out the chemical equation of that ion in water and how it can accept a proton causing OH concentration to increase. Using the molar concentration of the salte as the initial ion concentration and the ice table you can calculate the OH concentration and then the hydronium concentration and finally the pH.

[Ashlyn Sloane 1J]

I don't think you need to use molar concentrations to determine if a salt is acidic or basic. I would look at #6 on Achieve Week 2 because that is how I determine if a salt is acidic or basic. I answered this on a different question last week:

One helpful rule of thumb is to remember that a neutral salt contains a cation from a strong base and an anion from a strong acid. You can basically take a compound and break it into the anion and the cation. Then, identify whether that anion matches an anion of a strong acid from the list we need to memorize. Next, identify whether that cation matches the cation of a strong base from the same list.

e.g. NH4ClO4

HClO4 is a strong acid, and there are no strong bases that contain NH4. Therefore, NH4 is a "weak base" component and ClO4 is a "strong acid" component, so the whole molecule is acidic.

I attached a screenshot of how I identify them in case that's helpful.