IV. Buffers are solutions that contain both a conjugate weak acid and its conjugate weak base in significant (typically> 0.1M) concentrations. Some of the combinations below can be used to make buffers, and some cannot. If the combination could be used to make a buffer, then write \"buffer\", and indicate which is the acid and which is the base. If it could not form a buffer, then write \"not a buffer\" and tell why it is not a buffer (either reason 1, 2 or both): 1. It does not contain a conjugate acid/base pair. 2. It contains a conjugate acid base/pair but they are not weak conjugate acid / weak conjugate base pair. Examples 1. H,SO (aq) +NaHSO (aq)? Not a buffer. Reason 2 (Aqueous NaHSO, contains the ions Na and HSO. thus the solution contains the conjugate acid/base pair, H,So HSO, but H SO, is a strong acid.) 2. HCN aq) KCN(aq)? Buffer HCN is a weak acid, CN is its conjugate weak base. (Aqueous KCN contains the ions K and CN) 1. HCI(aq)NaCl(aq) 2. Na HPO (a NaH PO (aq) 3. NH Cl(aq) +NH,(aq) 4. H30\' + OH Solution Answer: 1) HCl & NaCl Not a Buffer Reason: HCl is a strong acid. 2) Na 2 HPO 4 & NaH 2 PO 4 . Buffer. Reason: NaH 2 PO 4 . gives ions Na+ and H 2 PO 4 - (aq) whereas NaH 2 PO 4 . gives 2Na+ and HPO 4 . 2- (aq) inos. Where, H 2 PO 4 - (aq) is weak Acid (in this context) and HPO 4 . 2- (aq) is conjugate base. 3) NH4Cl & NH3 Buffer Reason: NH4Cl ionizes to give NH4+ & Cl- ions. Nh4+ is a conjugate acid and NH3 is weak base. 4) H3O+ and HO-. Not Buffer. Reason: H3O+ is strong acid and HO- is strong base. =================XXXXXXXXXXXXXXXXX===================== .

1. IV. Buffers are solutions that contain both a conjugate weak acid and its conjugate weak base in
significant (typically> 0.1M) concentrations. Some of the combinations below can be used to
make buffers, and some cannot. If the combination could be used to make a buffer, then write
"buffer", and indicate which is the acid and which is the base. If it could not form a buffer, then
write "not a buffer" and tell why it is not a buffer (either reason 1, 2 or both): 1. It does not
contain a conjugate acid/base pair. 2. It contains a conjugate acid base/pair but they are not weak
conjugate acid / weak conjugate base pair. Examples 1. H,SO (aq) +NaHSO (aq)? Not a buffer.
Reason 2 (Aqueous NaHSO, contains the ions Na and HSO. thus the solution contains the
conjugate acid/base pair, H,So HSO, but H SO, is a strong acid.) 2. HCN aq) KCN(aq)? Buffer
HCN is a weak acid, CN is its conjugate weak base. (Aqueous KCN contains the ions K and CN)
1. HCI(aq)NaCl(aq) 2. Na HPO (a NaH PO (aq) 3. NH Cl(aq) +NH,(aq) 4. H30' + OH
Solution
Answer:
1) HCl & NaCl Not a Buffer
Reason: HCl is a strong acid.
2) Na 2 HPO 4 & NaH 2 PO 4 . Buffer.
Reason: NaH 2 PO 4 . gives ions Na+ and H 2 PO 4
-
(aq) whereas NaH 2 PO 4 . gives 2Na+ and
HPO 4 . 2-
(aq) inos.
Where, H 2 PO 4
-
(aq) is weak Acid (in this context) and HPO 4 . 2-
(aq) is conjugate base.
3) NH4Cl & NH3 Buffer
Reason: NH4Cl ionizes to give NH4+ & Cl- ions. Nh4+ is a conjugate acid and NH3 is weak
base.
4) H3O+ and HO-. Not Buffer.
Reason: H3O+ is strong acid and HO- is strong base.

2. =================XXXXXXXXXXXXXXXXX=====================