Chemistry Help?

[Bigbirdo]

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1. PH of cation salt is greater than 7 because HCl + NH3 ----- NH4+ + Cl-. Can someone show me how the same rule is true for Mg(OH)2? (This is not on the list of strong base that Chad gave me, so I guess it is a weak base.)
2. For question 110, Cu, Ag, Ag can be salts of weak base. How come they don't undergoes acid-base reactions that can affect the PH?
3. What are some common charges we should know for the chemistry section? I have encountered problems that you have to know the charge of the ions (Example: Qs 42 from destroyer)
   

 

[disciple155]

I believe the answer is C. Since BaF is a basic salt... hydrolysis rxn will yield HF and OH which affects pH. I may be wrong, but I think the reason why Cu and Ag do not affect the pH is because Cu and Ag is generally unreactive. Although, I know Cu is reactive with concentrated nitric acid. Hopefully that helps! Good luck! Hopefully someone else will be able to provide a better answer.

 

[Bigbirdo]

Thank you for your input. Anyone else?

 

[Daneosaurus]

1. PH of cation salt is greater than 7 because HCl + NH3 ----- NH4+ + Cl-. Can someone show me how the same rule is true for Mg(OH)2? (This is not on the list of strong base that Chad gave me, so I guess it is a weak base.)
2. For question 110, Cu, Ag, Ag can be salts of weak base. How come they don't undergoes acid-base reactions that can affect the PH?
3. What are some common charges we should know for the chemistry section? I have encountered problems that you have to know the charge of the ions (Example: Qs 42 from destroyer) View attachment 182136

Chad says he would include Mg(OH)2 as a strong base, even though most textbooks don't. I actually watched that one today as a refresher.

 

[Bigbirdo]

Chad says he would include Mg(OH)2 as a strong base, even though most textbooks don't. I actually watched that one today as a refresher.

What if I change Mg(OH)2 to a real base like Fe(OH)2, how does cation Fe2+ yield a acidic solution? I have only seen how NH4+ yields a acidic solution so far....

 

[disciple155]

Chad refers to this in one of his videos. I forget which one, but where he discusses all cations are acidic except the negligible ones (group 1 and 2 metals), so I'd assume that is why Fe yields an acidic solution.

 

[Daneosaurus]

All transition metals are Lewis acids.