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Find pH and mass salt mixture

1. Carbon dioxide dissolves in water to form carbonic acid, which is primarily dissolved CO_2. Dissolved CO_2 satisfies the equilibrium equation

The acid dissociation constants listed in most standard reference texts for carbonic acid actually apply to dissolved CO_2. For a CO_2 partial pressure of 7.7×10-4 atm in the atmosphere, what is the pH of water in equilibrium with the atmosphere?

2 Phosphoric acid is a triprotic acid with the following pKa values:

You wish to prepare 1.000 L of a 0.0100 M phosphate buffer at pH 7.53. To do this, you choose to use mix the two salt forms involved in the second ionization, NaH_2PO_4 and Na_2HPO_4, in a 1.000 L volumetric flask and add water to the mark. What mass of each salt will you add to the mixture?

= ______________g

= _______________g

What other combination of phosphoric acid and/or its salts could be mixed to prepare this buffer? (Check all that apply).

H_3PO_4 and NaH_2PO_4
H_3PO_4 and Na_2HPO_4
H_3PO_4 and Na_3PO_4
NaH_2PO_4 and Na_3PO_4
Na_2HPO_4 and Na_3PO_4.

Solution Summary

The solution finds the pH and mass of a salt mixture.