Destroyer GC #23

[Mamona]

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In the solutions part there is extra examples and I can't understand why FeCl3 and AlCl3 are consider acidic solutions. It is mention in the solution that Cl is an spectator ion, so how should I approach this???

 

[yakuza]

In the solutions part there is extra examples and I can't understand why FeCl3 and AlCl3 are consider acidic solutions. It is mention in the solution that Cl is an spectator ion, so how should I approach this???

The destroyer guy makes it more complicated than it is. Here's the BEST way to do these problems.

K first, there are certain cations and anions that are SO WEAK, they're considered neutral. They are:

Cations (conjugate acids) Anions (conjugate bases)

Li+ ______________________Cl-
Na+ ______________________Br-
K+
Rb+ ______________________I-
Cs+ ______________________NO3-
Ca+ _______________________ClO4-
Sr++ _____________________ClO3-
Ba++

With this said, cross all of these out.
If the left over thing is a cation..its acidic
And if the left over this is an anion..its basic
And if they both cross out, its neutral


So in the problem we have:
KBr --------->> cross out K and Br, so neutral
NH4NO3 -------> do the same for the rest and your set
NaF
KCN
Na2CO3

 

[Mamona]

The destroyer guy makes it more complicated than it is. Here's the BEST way to do these problems.

K first, there are certain cations and anions that are SO WEAK, they're considered neutral. They are:

Cations (conjugate acids) Anions (conjugate bases)

Li+ ______________________Cl-
Na+ ______________________Br-
K+
Rb+ ______________________I-
Cs+ ______________________NO3-
Ca+ _______________________ClO4-
Sr++ _____________________ClO3-
Ba++

With this said, cross all of these out.
If the left over thing is a cation..its acidic
And if the left over this is an anion..its basic
And if they both cross out, its neutral


So in the problem we have:
KBr --------->> cross out K and Br, so neutral
NH4NO3 -------> do the same for the rest and your set
NaF
KCN
Na2CO3

Thank you so much I think I got it, so in the case of FeCl3 I cancel the Cl end up with Fe3+ and therefor be acidic????

 

[yakuza]

Yup. Also memorize the list I gave you, if it's not on the list then don't cross them out.

 

[yakuza]

#71 is the same thing, try it there.

 

[Mamona]

Thank you very much

 

[Dental4ever]

wow.this method works. i alwasy have trouble with this kind of problem. Thanks