Why Does Na2CO3 Result in a Basic Solution in Water?

[kasse]

Homework Statement

Explain why Na₂CO₃ gives a basic solution when dissolved in water.

The Attempt at a Solution

The cation is Na⁺ while the anion is CO₃^2-. The cation has no affinity for neither protons nor hydroxide ions. The anion should have basic properties to make a basic solution. Does this mean that HCO₃^- is a weak acid? I cannot find it in my table of weak acids.

 

[symbolipoint]

Why basic? To be brief: Hydrolysis. HCO3-, is from Carbonic acid. Carbonic acid is a diprotic acid, and when you look for the dissociation constant you need to look for the one for carbonic acid which will show you the values for the first AND the second dissociations.

Carbonic Acid: \[<br /> H_2 CO_3 <br /> \]<br />

the first dissociation is stronger than the second dissociation.

 

[chemisttree]

Homework Statement

Explain why Na₂CO₃ gives a basic solution when dissolved in water.

The Attempt at a Solution

The cation is Na⁺ while the anion is CO₃^2-. The cation has no affinity for neither protons nor hydroxide ions. The anion should have basic properties to make a basic solution. Does this mean that HCO₃^- is a weak acid? I cannot find it in my table of weak acids.

The pertinent reactions you need to conceptualize are:

1) CO₃^-2 + H₂O <-------> HCO₃^- + OH^-

and,

2) HCO₃^- + H₂O <-----> H₂CO₃ + OH^-