A buffer solution with pH 9 is to be prepared by mixing NH4Cl and NH4OH . Calculate the number of moles of NH4Cl that should be added to 1 L of 1.0 text M text NH4OH .

Question

A buffer solution with pH 9 is to be prepared by mixing NH4Cl and NH4OH . Calculate the number of moles of NH4Cl that should be added to 1 L of 1.0 text M text NH4OH . (A) 3.4 (B) 2.6 (C) 1.5 (D) 1.99

Tardigrade Admin · Accepted Answer

pOH=- log Kb+ log [ (salt/base) ] [14-pH]=- log [1.8× 10-5]+[ (salt/1.0) ] 5=4.7+ log [ (salt/1.0) ] log [ (salt/1.0) ]=5-4.7=0.3 [salt]=antilog text 0.3 [salt]=1.995

Q. A buffer solution with pH 9 is to be prepared by mixing $N H_{4} Cl$ and $N H_{4} O H$ . Calculate the number of moles of $N H_{4} Cl$ that should be added to 1 L of $1.0 M N H_{4} O H$ .

3.4

2.6

1.5

1.99

$pO H = - lo g K_{b} + lo g [\frac{s a lt}{ba se}]$
$[14 - p H] = - lo g [1.8 \times 10^{- 5}] + [\frac{s a lt}{1.0}]$
$5 = 4.7 + lo g [\frac{s a lt}{1.0}]$
$lo g [\frac{s a lt}{1.0}] = 5 - 4.7 = 0.3$
$[s a lt] = an t i l o g 0.3$
$[s a lt] = 1.995$

Q. A buffer solution with pH 9 is to be prepared by mixing NH4​Cl and NH4​OH . Calculate the number of moles of NH4​Cl that should be added to 1 L of 1.0MNH4​OH .

3.4

2.6

1.5

1.99

pOH=−logKb​+log[basesalt​] [14−pH]=−log[1.8×10−5]+[1.0salt​] 5=4.7+log[1.0salt​] log[1.0salt​]=5−4.7=0.3 [salt]=antilog0.3 [salt]=1.995

Q. A buffer solution with pH 9 is to be prepared by mixing $N H_{4} Cl$ and $N H_{4} O H$ . Calculate the number of moles of $N H_{4} Cl$ that should be added to 1 L of $1.0 M N H_{4} O H$ .

$pO H = - lo g K_{b} + lo g [\frac{s a lt}{ba se}]$
$[14 - p H] = - lo g [1.8 \times 10^{- 5}] + [\frac{s a lt}{1.0}]$
$5 = 4.7 + lo g [\frac{s a lt}{1.0}]$
$lo g [\frac{s a lt}{1.0}] = 5 - 4.7 = 0.3$
$[s a lt] = an t i l o g 0.3$
$[s a lt] = 1.995$