[sofiaAr]

I need to choose at least 1 compound which

1. weak base in aqueous solution
2. weak acid in aqueous solution
3. room temperature solid compound with characteristics of Ionic compounds




from the following(The question relates to the compounds only at room temperature):
H2,Hg,He,H2O,H2S,H2Se,CH4,NH3,MgH2

now I know that : H2,He,H2O,H2S,H2Se,
,CH4,NH3. are gases in room temp

so I'm left with MgH2 and Hg that are both solid.
now the problem is that MgH2: Metal hydrides are very strong bases and Mercury does not dissolve in water to act as acid/base.

so what is the right answer?
thanks so much!

[Babcock_Hall]

Some things that are gases at room temperature can still dissolve in water.

[sofiaAr]

I know that but the question asks about a solid compound that comply with all conditions

(1. weak base in aqueous solution
2. weak acid in aqueous solution
3. solid matter in room temp that acting(character) as ion )

[Babcock_Hall]

You have some errors in your comments.  What is the melting point of mercury?  What is the boiling point of H₂O?  Also, I am not sure about what (3) means.

[sofiaAr]

The question relates to the compounds only at room temperature .

I need to choose a compound which acts like weak base and weak acid in aqueous solution and also in room temperature this compound is solid with characteristics of Ionic compounds

[AWK]

In your compounds you have only one weak base (well known) and two wek acids (one also well known).

[sofiaAr]

Do you mind to tell me which compounds?

[AWK]

I gave you a hint. This is your homework, not mine.
There is also only one solid ionic compound.

[sofiaAr]

is it MgH2?

[sofiaAr]

Can someone give me a source (website) that I can use in order to answer this question. thanks

[AWK]

is it MgH2?

Yes, hydrides of the first and the second group of elements are ionic in solid state.

Do you know an Arhenius of Bronsted definition of acids and bases?

[sofiaAr]

I know Arrhenius and J.Bronsted definitions

but isn't MgH2 strong base because its from the 2 group?

[Arkcon]

I know Arrhenius and J.Bronsted definitions

Good.

Type them out, here, for us.  And then compare your questions to the definitions.  That's how you'll solve this problem for yourself.

[sofiaAr]

Arrhenius definition :
acid - increases the concentration of H+/proton when in aqueous solution.
base - increases the  OH- concentration when in aqueous solution
Bronsted-Lowry definition :
acid - proton/H+ donor
base - proton/H+ acceptor


there is one equations: MgH2+2H2O=Mg(OH)2+2H2

[AWK]

My second hint concerned weak acids and bases - your questions 1 and 2.