Basic Buffer Action

Q. In a buffer solution containing equal concentration of B- and HB, the Kb for B- is 10-10. The pH of buffer solution is

Q. What is the pH of 0.0001M HCl solution?

Q. 8. Explain how does a mixture of equimolar amounts of NH4OH and NH4Cl act as a basic buffer when 1)small amounts of acid 2)small amounts of base is added.

Q. 71 Calculate the amount of (NH4)2SO4 which must be added to 500 ml of 0.2 (M) NH3 to yield asolution of pH = 9.35. (pKb(NH4OH) = 4.74 )

Q. $20mL$ of $0.1M$ $H_{2}S{O}_4$ solution is mixed with $30mL$ of $0.2M$ $N{H}_{4}OH$ solution. The $pH$ of the resultant solution is:
[$p{K}_b$ of $N{H}_{4}OH=4.7$]

1. 7
2. 9
3. 5
4. 12

Q. in a basic buffer 0.0025mole of NH_4Cl and 0.15 mole of NH_4OH are present .The pH of the solution will be( pKa)= 4.74

Q. Find the $pH$ of $1L$ of a buffer solution containing $0.01MN{H}_{4}Cl$ and $0.05MN{H}_{4}OH$ at ${25}^{\circ }C$
The base dissociation constant for $N{H}_{4}OH$ is $1.8\times {10}^{-5}$
Take $log\left(1.8\right)=0.26$

1. 9.96
2. 10.36
3. 11.56
4. 12.56

Q. Calculate the concentration of $N{H}_{3}andN{H}_4^{+}C{l}^{-}$ present in the buffer solution of pH = 9, when total concentration of buffering reagents is 0.6 $mol{L}^{-1}.$ Take $p{K}_b$ for $N{H}_3=4.7,log2=0.3$

1. $\left[N{H}_4^{+}C{l}^{-}\right]=0.1M\text{and}\left[N{H}_3\right]=0.3M$
2. $\left[N{H}_4^{+}C{l}^{-}\right]=0.6M\text{and}\left[N{H}_3\right]=0.6M$
3. $\left[N{H}_4^{+}C{l}^{-}\right]=0.8M\text{and}\left[N{H}_3\right]=0.2M$
4. $\left[N{H}_4^{+}C{l}^{-}\right]=0.4M\text{and}\left[N{H}_3\right]=0.2M$

Q.

43.In the neutralization process of $H_{3}P{O}_4$ and NaOH, the number of acid buffers formed will be-

a. 2,

b. 3,

c. 4,

d. 1

Q. The buffer capacity is equal to:

1. $\frac{\Delta n}{\Delta pH}$
2. $\frac{pH}{\Delta n}$
3. $\pm 1p{K}_a$
4. None of these

Q.

The pH of the salt used to make tasty and crispy pakoras is 8.4. Identify the salt and write a chemical equation for its formation and also list its two uses?

Q.

A mixture of CH₃COOH and CH₃COONa behaves as

1. Ionic buffer

2. Acidic buffer

3. Neutral buffer

4. Basic buffer

Q. $20mL$ of $0.1M$ $H_{2}S{O}_4$ solution is mixed with $30mL$ of $0.2M$ $N{H}_{4}OH$ solution. The $pH$ of the resultant solution is:
[$p{K}_b$ of $N{H}_{4}OH=4.7$]

1. 7
2. 9
3. 5
4. 12

Q. Which will make a basic buffer?

1. $50mL$ of $0.1M$ $NaOH$ + $25mL$ of $0.1M$ $C{H}_{3}COOH$
2. $100mL$ of $0.1M$ $C{H}_{3}COOH$ + $100mL$ of $0.1M$ $NaOH$
3. $100mL$ of $0.1M$ $HCl$ + $200mL$ of $0.1M$ $N{H}_{4}OH$
4. $100mL$ of $0.1M$ $HCl$ + $100mL$ of $0.1M$ $NaOH$

Q. 68. At 100^° C the K of water is 55 times its value at25^° C. What will be the pH of neutral solution?nd(log 55 = 1.74)(1) 6.13(2) 7.00(3) 7.87(4) 5.13

Q. 24. If the pH of a base is 14 at 25 C then on increasing temp to 35 C 1) ph will be more than 14 2) less than 14 3) equal to 14

Q. Give the relation between pH and pKa in a formula.

Q. A base has kb=8.1×10^{-8} inwhat amount should 0.02 (m)HCland0.02(m)of BOH be mixed to make 200ml of a buffer of pH 7

Q. If pH of 0.1\:M (NH_4)CO_3 solution is x, then pHof 0.01\:M\:(NH_4)CO_3 soluiton will be : \lbrack Also provide relation between pH and concetration\rbrack

Q. WHEN IS THE SOLUTION SAID TO BE NEUTRAL

Q. Calculate the weight (in $mg$) of $HCl$ that should be added to $100ml$ of $0.1MBOH$ to make a buffer solution of $pOH=6$.
$K_b\left(BOH\right)=1\times {10}^{-8}$ (assume there is no change in volume on addition of $HCl$)

1. 3.6
2. 4.6
3. 5.6
4. 6.6

Q. Calculate the weight (in $mg$) of $HCl$ that should be added to $100ml$ of $0.1MBOH$ to make a buffer solution of $pOH=6$.
$K_b\left(BOH\right)=1\times {10}^{-8}$ (assume there is no change in volume on addition of $HCl$)

1. 3.6
2. 4.6
3. 5.6
4. 6.6

Q. A certain buffer contains a weak base $AOH$ and its conjugate acid $\left(A^{+}\right)$ at ${25}^{\circ }C$.
The concentration of $A^{+}$ ions is twice the concentration of $AOH$.
Calculate the $pH$ of the buffer solution.
(Given base dissociation constant for $AOH$ is $K_b={10}^{-5}$)

1. 8.7
2. 4.3
3. 5.3
4. 9.7

Q. the pH of 0.1M NH_4Cl solution is (given pK_b=4.74)

Q.

what is the ph of blood?

Q. Freshly precipitated aluminium and magnesium hydroxides are stirred vigorously in a buffer solution containing $0.05{\text{mol L}}^{-1}$ of $N{H}_{4}OH$ and $0.25{\text{mol L}}^{-1}$ of $N{H}_{4}Cl$. Calculate the concentration of magnesium ions in solution.
$K_{sp}Al(OH{)}_3=6\times {10}^{-32}$
$K_{b}N{H}_{4}OH=1.8\times {10}^{-5}$
$K_{sp}Mg(OH{)}_2=6\times {10}^{-10}$

Q. Calculate the weight in mg of HCl added to 100 ml of 0.1 N BOH to have its pH = 6.6 and $K_b=6.25\times {10}^{-8};$ Antilog $(-7.4)=3.98\times {10}^{-8}.$ (Assume there is no change in volume on addition of $HCl$)

1. 300
2. 100
3. 425
4. 223

Q. Calculate the ratio of $C{H}_{3}N{H}_2$ to $C{H}_{3}N{H}_3^{+}C{l}^{-}$ required to create a buffer with pH = 10.14
$K_{b}ofC{H}_{3}N{H}_2=4.4\times {10}^{-4}$
take $log2.27=0.356,log0.313=-0.504$

1. 0.5
2. 1.05
3. 0.31
4. None of the above

Q. Why is Ca3(PO4)2 called a salt of weak acid and weak base ?

Q. buffer capacity is defined as the amount of acid or base that must be added to the buffer to cause
a) one unit change of PH
b) two """"""""""""""""
c) no change in Ph
d) the Phto equal PKa+-1