Acid, base; redox oxidation number questions?

[zadok]

I have a few questions. Please help cuz i have spent so many hours on them and i am stuck. i enclose the way i understand. Please correct me if i am wrong
1. Identify which one is acid, base, both, or nether and write reaction illustrate its properties in the water (showing if it's basic or acid)
a. H2CO3
b. KHCO3
c. NH3
d. NaCl
e. Na2SO4
f. NH4HSO4
g. NaO2CCO2H mono-sodium salt of oxalic acid


THIS IS WHAT I THINK OR WHAT I HAVE:

a. H2CO3- acid
H2CO3(aq)+H2O(l)->HCO3-(aq)+H3O(aq)
my question: is this correct? I read somewhere that H2CO3 can also be a base, but I could not find a reaction showing H2CO3 can act as a base. I found H2CO3 (aq)-.>H2O(l)+CO2 Is this action related to anything?
b. KHCO3-base
I am confused with what i found
KHCO3->K+(aq)+CO3-(aq)
CO3-(aq)+H2O(l)->HCO3-(aq)+OH-(aq)
HCO3-(aq)+H2O(l)->H2CO3(aq)+OH-
c. NH3- base
My question: can it be a acid? If it can, what is the reaction?
d. NaCl- salt
e. Na2SO4-salt
my question: i though when it produces something with OH means it's a base??? (or i am so wrong!!!)
f. NH4HSO4- i don't know. but it looks like it a conjugate acid
g. NaO2CCO2H mono sodium salt of oxalic acid- i don't know. I didn't find much information about this one


2. Determine the oxidation and reduction half reaction
a. gold metal dissolves in aqua regia to give (AuCl4)- and NO2
Au(aq)+3(NO3)-(aq)+6H+(aq)<->Au3+(aq)+…
Au3+(aq)+4Cl-(aq)<->(AuCl4)-
I read some of this in wikipidia but honestly i did not understand. I don't even understand the 2 reactions
b. Acidic potassium permanganate reacts with aqueous K2C2O4, producing carbon dioxide and Mn2+
3. Calculate pH of HClO with a given Ka and M. I just wanna make sure if what i did was correct. Because HClO is a strong acid so i don't need Ka value and still able to find its pH right? what i did was saying concentration of HClO=concentration of H3O and calculate by using -log(H3O+). Is this correct?
4. How to find the molarity of alcohol reacts with dichromate ion if i have the density of the solution (1.05g/mL) and the gram of alcohol in the solution?

I appreciate for any help. Honestly from the beginning of the semester i comprehend pretty well until this chapter, and i DON'T wanna be lost. I really don't

[ealahweemah72]

You are right about the H2CO3

KHCO3 probably will could react as both an acid or a base. The HCO3- could donate a proton if reacted with a strong base, or it could accept a proton if reacted with a stron acid.

NH3 is a base, It might be able to become an acid but would need a powerful base to be able to strip the H+ away from the NH3

NaCl = neutral

Na2SO4. SO4-2 is a base,, will form HSO4- and OH- with water.

NH4+ is an acid, and HSO4- is a weak base Probably neutralize themselves in solution

Oxalate ion is a base with a strong acid, and an acid with a strong base.

2. Au will be oxidized and lose 3e-.

The half reaction for acid permangante is MnO4- + 8H+ + 5e- --------> Mn+2 + 4 H2O. I don't know the half reaction for the C2O4-2 ion. You 'll have to look it up.

You see to have #3 correct

The redox reaction for dichromate and alcohol is:

Cr2O7-2 + H+ + C2H5OH ----> Cr+3 + H2O + CH3COOH