Calculate the pOH of an aqueous solution of 146.6 ml of 0.000625 M HBr(aq) after dilution to 850 ml.
To calculate the pOH of the aqueous solution, we need to know the concentration of hydroxide ions (OH-) in the solution.
Since HBr is a strong acid, it completely dissociates in water. Therefore, the concentration of H+ ions can be considered equal to the concentration of HBr.
Given that we have diluted the solution from 146.6 ml to 850 ml, the moles or amount of HBr remains the same.
First, let's calculate the moles of HBr in the original solution using the formula:
moles = concentration * volume
moles of HBr = 0.000625 mol/L * 0.1466 L = 0.00009165 mol
Since the moles of HBr do not change after dilution, we can calculate the new concentration of HBr in the diluted solution using the formula:
concentration = moles / volume
new concentration of HBr = 0.00009165 mol / 0.85 L = 0.00010794 mol/L
Now, to find the pOH, we need to calculate the concentration of OH- ions.
Since HBr is a strong acid, it donates H+ ions, making the solution acidic. In water, water molecules can act as bases and accept H+ ions to form OH- ions. However, the extent to which water molecules dissociate is very small, so we can consider the concentration of OH- ions to be negligible compared to the concentration of HBr.
Therefore, we can assume the concentration of OH- ions as 0 in this case.
The pOH is the negative logarithm of the hydroxide ion concentration, which is given by:
pOH = -log[OH-]
Since [OH-] is approximately zero, the pOH of this solution is also approximately zero.
Thus, the pOH of the aqueous solution after dilution is approximately 0.