pH of Polybasic Acids or Polyacidic Bases

The number of ${\mathrm{S}}^{2-}$ ions present in $1 \mathrm{L} 0.1\mathrm{ }\mathrm{M} {\mathrm{H}}_2\mathrm{S}$ solution having $\left[{\mathrm{H}}^{+}\right]=0.1 \mathrm{M}$ is

$$\begin{gathered} \left({\mathrm{H}}_2\mathrm{S}\rightleftharpoons 2{\mathrm{H}}^{+}+{\mathrm{S}}^{2-}\right) \\ \left({\mathrm{K}}_{\mathrm{a}}=1.1\times {10}^{-21}\right) \end{gathered}$$

For ${10}^{-2}\left(\mathrm{M}\right){\mathrm{H}}_3\mathrm{P}{\mathrm{O}}_3$ solution which of the following relations is correct?

$\mathrm{p}{{\mathrm{K}}_{\mathrm{a}}}_1\mathrm{ },\mathrm{ }\mathrm{p}{{\mathrm{K}}_{\mathrm{a}}}_2$ and $\mathrm{p}{{\mathrm{K}}_{\mathrm{a}}}_3$ of ${\mathrm{H}}_3\mathrm{P}{\mathrm{O}}_4$ are respectively x, y and z. pH of 0.01 M $\mathrm{N}{\mathrm{a}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4$ solution is:

${\mathrm{H}}_3{\mathrm{P}\mathrm{O}}_4$ is a weak triprotic acid; approximate $\mathrm{p}\mathrm{H}$ of $0.1\mathrm{M}\mathrm{ }\mathrm{N}{\mathrm{a}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4\mathrm{ }\left(\mathrm{a}\mathrm{q}\right)$ is calculated by 

For ${10}^{–2}\left(\mathrm{M}\right)\mathrm{ }{\mathrm{H}}_3{\mathrm{P}\mathrm{O}}_3$ solution which of the following relations is correct?

For ${10}^{–2}\left(\mathrm{M}\right)\mathrm{ }{\mathrm{H}}_3{\mathrm{P}\mathrm{O}}_3$ solution which of the following relations is correct?

What is the $\mathrm{p}\mathrm{H}$ of $0.01\mathrm{ }\mathrm{M}$ glycine solution? For glycine, $\mathrm{K}{\mathrm{a}}_1=4.5\times 10^{-\mathrm{3\; }}$and  $\mathrm{K}{\mathrm{a}}_2=1.7\times 10^{-\mathrm{10\; }}$at $298\mathrm{ }\mathrm{K}$

Statement I: The dissociation constants of polyprotic acid are in the order ${\mathrm{k}}_1 > {\mathrm{k}}_2 > {\mathrm{k}}_3.$

Statement II: The $\left[{\mathrm{H}}^{+}\right]$  furnished in the first step of dissociation exerts common ion effect to reduce the second dissociation and so on.

$0.1 \mathrm{M}$ solution of ${\mathrm{H}}_3\mathrm{A}$ being a weak tribasic acid having  ${\text{K}}_{{\text{a}}_1},K_{{\text{a}}_2}and{\text{K}}_{{\text{a}}_3}$ as ${10}^{-5} , {10}^{-9}$ and ${10}^{-13}$ respectively. If $\mathrm{pX}$ represents  $-\text{log}\frac{\left[{\text{A}}^{3-}\right]}{\left[{\text{HA}}^{2-}\right]},$  then the value of $\mathrm{pX}$ is:

Mark out the incorrect statements :

$$\begin{gathered} \begin{array}{ccccc}{\mathrm{H}}_3{\mathrm{PO}}_4& \rightleftharpoons & {\mathrm{H}}^{\oplus }+{\mathrm{H}}_2{\mathrm{PO}}_4^{\ominus }& \mathrm{;}& {\mathrm{K}}_{{\mathrm{a}}_1}:\end{array}{10}^{-3} \\ \begin{array}{ccccc}{\mathrm{H}}_2{\mathrm{PO}}_4^{\ominus }& \rightleftharpoons & {\mathrm{H}}^{\oplus }+{\mathrm{HPO}}_4^{2-}& ;& {\mathrm{K}}_{{\mathrm{a}}_2}:\end{array} {10}^{-7} \\ \begin{array}{ccccc}{\mathrm{HPO}}_4^{2-}& \rightleftharpoons & {\mathrm{H}}^{\oplus }+{\mathrm{PO}}_4^{3-}& ;& {\mathrm{K}}_{{\mathrm{a}}_3}:\end{array} {10}^{-13} \end{gathered}$$

The first ionization constant of ${\mathrm{H}}_2\mathrm{S}$ is $9.1\times {10}^{-8}$. Calculate the concentration of ${\mathrm{HS}}^{-}$ ion in its $0.1 \mathrm{M}$ solution. How will this concentration be affected, if the solution is $0.1 \mathrm{M}$ in $\mathrm{HCl}$ also? If the second dissociation constant of ${\mathrm{H}}_2\mathrm{S}$ is $1.2\times {10}^{-13}$, then calculate the concentration of ${\mathrm{S}}^{2-}$ under both conditions. Select these four answers from the choices given below.

In an aqueous solution the ionisation constants for carbonic acid are ${\mathrm{K}}_1 = 4.2 \times {10}^{-7}$ and ${\mathrm{K}}_2 = 4.8 \times {10}^{-11}$
Select the correct statement for a saturated $0.034\mathrm{M}$ solution of carbonic acid

The first and second dissociation constants of an acid ${\text{H}}_{\text{2}}\text{A}$ are $1.0\times {10}^{-5}$   and $\text{5}\times {10}^{-10}$, respectively. What is the overall dissociation constant of the acid?

Bromine in excess is dropped to a $0.01\text{M}$ ${\mathrm{SO}}_2$. All of ${\mathrm{SO}}_2$ is oxidized to ${\mathrm{H}}_2{\mathrm{SO}}_4$ and the excess ${\mathrm{Br}}_2$ is removed by flushing with gaseous ${\mathrm{N}}_2$. Determine the $\text{pH}$ of the resulting solution assuming ${\mathrm{K}}_{\mathrm{a}1}$ of ${\mathrm{H}}_2{\mathrm{SO}}_4$ very large & ${\text{K}}_{\text{a2}}={10}^{-2}.$ Take the value of $\log (3.24) = 0.51$. Give the answer to the nearest integer value after multiplying with 100.

Phosphoric acid ionizes as per equations

$\begin{array}{ccccccc}{\text{H}}_3{\text{PO}}_4& \rightleftharpoons & {\text{H}}^{+}& +& {\text{H}}_2{\text{PO}}_4^{-}& \text{;}& {\text{K}}_1=7\times 10^{-3}\\ {\text{H}}_2{\text{PO}}_4^{-1}& \rightleftharpoons & {\text{H}}^{+}& +& {\text{HPO}}_4^{2-}& \text{;}& {\text{K}}_2=6\times 10^{-8}\\ {\text{HPO}}_4^{2-}& \rightleftharpoons & {\text{H}}^{+}& +& {\text{PO}}_4^{3-}& \text{;}& {\text{K}}_3=4\text{.}5\times 10^{-13}\end{array}$

After identifying the species best suitable for a buffer with pH = 7; assume 50 mL of buffer prepared as per this information in which more abundant species has a concentration of 0.10M. If to this solution 20 mL of 0.1M NaOH added what will be the new pH.

The species present in solution when CO₂ is dissolved in water are

If ${\text{K}}_{{\text{a}}_1}\text{, }{\text{K}}_{{\text{a}}_{\mathrm{2 }}}\text{and }{\text{K}}_{{\text{a}}_3}$  be the first, second, and third ionization constant of H₃PO₄ and ${\text{K}}_{{\text{a}}_1}\gg {\text{K}}_{{\text{a}}_2}\gg {\text{K}}_{{\text{a}}_3}$ which is/are correct?

$10 \mathrm{mL}$ of $0.1 \mathrm{M}$ tribasic acid ${\mathrm{H}}_3\mathrm{A}$ is titrated with  $0.1 \mathrm{M} \mathrm{NaOH}$ solution. What is the ratio of $\frac{\left[{\text{H}}_3\text{A}\right]}{\left[{\text{A}}^{3-}\right]}$ at $2^{\mathrm{nd}}$ equivalence point? $\left[ {\mathrm{K}}_{{\mathrm{a}}_1}={10}^{-3}, {\mathrm{K}}_{{\mathrm{a}}_2}={10}^{-8}, {\mathrm{K}}_{{\mathrm{a}}_3}={10}^{-12}\right]$

$10 \mathrm{mL} \mathrm{of} 0.1 \mathrm{M}$ tribasic acid ${\mathrm{H}}_3\mathrm{A}$ is titrated with $0.1 \mathrm{M} \mathrm{NaOH}$ solution. What is the ratio of $\frac{\left[{\mathrm{H}}_3\mathrm{A}\right]}{\left[{\mathrm{A}}^{3-}\right]}$ at $2^{\mathrm{nd}}$ equivalence point? $\left[\mathrm{Given}: {\mathrm{K}}_{{\mathrm{a}}_1}={10}^{-3}, {\mathrm{K}}_{{\mathrm{a}}_2}={10}^{-8 }\mathrm{and} {\mathrm{K}}_{{\mathrm{a}}_3}={10}^{-12}\right]$

What is the $\mathrm{pH}$ of $0.01 \mathrm{M}$ glycine solution? For glycine ${\text{K}}_{{\text{a}}_1}=4\text{.}5\times 10^{-\mathrm{3 }}\text{;}$  ${\text{K}}_{{\text{a}}_2}=1\text{.}7\times 10^{-1\mathrm{0 }}\text{;}$ at $298 \mathrm{K}$ :