What is the ratio of the molarities of PO3^4- and HPO4^2− ions in a buffer solution having a pH of 13.16?
What mass of K3PO4 must be added to 1 L
of 0.1 M K2HPO4(aq) to prepare a buffer
solution with a pH of 13.16?
Answer in units of g
What mass of K2HPO4 must be added to
1 L of 0.1 M K3PO4(aq) to prepare a buffer solution with a pH of 13.16?
Answer in units of g
What volume of 0.15 M K3PO4(aq) must be
added to 50 mL of 0.1 M K2HPO4(aq) to
prepare a buffer solution with a pH of 13.16?
Answer in units of mL
To determine the ratio of molarities of PO3^4- and HPO4^2− ions in a buffer solution with a pH of 13.16, we need to understand the relationship between pH and the acid-base equilibrium. In this case, we are dealing with the phosphate buffer system, where the acid is H2PO4^- (dihydrogen phosphate ion) and the base is HPO4^2− (monohydrogen phosphate ion).
The acid-base equilibrium in the phosphate buffer system is as follows:
H2PO4^- ⇌ HPO4^2− + H+
The equilibrium constant for this reaction is denoted as Ka such that:
Ka = [HPO4^2−] [H+] / [H2PO4^-]
In an aqueous solution, the pH can be determined using the equation:
pH = -log[H+]
Given that the pH is 13.16, we can calculate the concentration of H+ ions using the equation:
[H+] = 10^(-pH)
Now, let's solve the ratio of molarities using these equations:
1. Calculate the concentration of H+ ions:
[H+] = 10^(-13.16)
2. Since the concentration of H+ ions equals the concentration of HPO4^2- ions in the buffer solution, we have:
[HPO4^2−] = 10^(-13.16) M
3. The concentration of H2PO4^- ions can be calculated using the equation:
[H2PO4^-] = [HPO4^2−] / Ka
4. The ratio of molarities is given by:
[HPO4^2−] / [H2PO4^-]
Now that we have the ratio of molarities, we can move on to the next questions.
To determine the mass of K3PO4 needed to prepare a buffer solution, we must consider the balanced chemical equation for the reaction between K3PO4 and K2HPO4:
K3PO4 + K2HPO4 → 2K2HPO4
1. Determine the moles of K2HPO4 using the equation:
moles = concentration (M) × volume (L)
2. Calculate the moles of K3PO4 required using the stoichiometric ratio of 1:1 between K3PO4 and K2HPO4.
3. Convert the moles of K3PO4 to grams using the molar mass of K3PO4.
To determine the mass of K2HPO4 needed to prepare a buffer solution, we also need to consider the balanced chemical equation:
K3PO4 + K2HPO4 → 2K2HPO4
1. Determine the moles of K3PO4 using the equation:
moles = concentration (M) × volume (L)
2. Calculate the moles of K2HPO4 required using the stoichiometric ratio of 1:1 between K3PO4 and K2HPO4.
3. Convert the moles of K2HPO4 to grams using the molar mass of K2HPO4.
To determine the volume of 0.15 M K3PO4 needed to prepare a buffer solution, we need to consider the balanced chemical equation:
K3PO4 + K2HPO4 → 2K2HPO4
1. Determine the moles of K2HPO4 using the equation:
moles = concentration (M) × volume (L)
2. Calculate the moles of K3PO4 required using the stoichiometric ratio of 1:1 between K3PO4 and K2HPO4.
3. Convert the moles of K3PO4 to volume using the equation:
volume (L) = moles / concentration (M)
Note: All necessary molar masses and balanced chemical equations can be obtained from a reliable source or chemical reference material.