Starting with equal concentrations of all solutes, predict the direction in which the following reaction will proceed.
H3PO4(aq) + HCO3-(aq) �¨ H2PO4-(aq) + H2CO3(aq)
a. left
b. right
c. no net reaction
Hey - just look up the Ka (or Kb respectively) values for each compound, and see which is bigger. Stronger acid = bigger Ka and that will dictate which direction it will go in. In this case, H3PO4 is the strongest acid (highest Ka) and therefore the direction of that reaction will proceed TO THE RIGHT =). Hope this helps.
To predict the direction in which a chemical reaction will proceed, we can consider the concept of Le Chatelier's principle. According to this principle, if a system at equilibrium is disturbed by a change in temperature, pressure, or the concentration of one of the reactants/products, the system will adjust to counteract the change and re-establish equilibrium.
In the given reaction, we start with equal concentrations of all solutes. Let's analyze the changes that occur when the reaction proceeds:
H3PO4(aq) + HCO3-(aq) ↔ H2PO4-(aq) + H2CO3(aq)
When the reaction proceeds to the right, the concentration of H2PO4- and H2CO3 will increase, while the concentration of H3PO4 and HCO3- will decrease. This means that we are consuming H3PO4 and HCO3- while producing H2PO4- and H2CO3.
Now, let's apply Le Chatelier's principle and analyze the changes that would occur to re-establish equilibrium:
1. If the concentration of H2PO4- increases, the reaction will shift to the left to consume H2PO4- and produce more H3PO4.
2. If the concentration of H2CO3 increases, the reaction will shift to the left to consume H2CO3 and produce more HCO3-.
Based on the above considerations, we can determine that the reaction will proceed to the left, resulting in a decrease in the concentrations of H2PO4- and H2CO3, and an increase in the concentrations of H3PO4 and HCO3-. Therefore, the answer is option a. left.