Buffers & Buffering Capacity Questions
And Answers
pH cof ca cbuffer csolution cdepends con c- cAnswer c- cthe cpKa cof cthe cacid cand cthe cratio c[A-]/[HA].
Henderson-Hasselbalch cequation c- cAnswer c- cpH c= cpKa c+ clog([A-]/[HA])
This cequation cis cused cto cdetermine cthe cpH cof ca cbuffer csolution.
Buffer c- cAnswer c- can caqueous csolution cof ca cWEAK cacid c(HA) cand cits cconjugate cbase c(A-). cThey ccan cbe
cmade cin cthree cways:
1. cPartially ctitrating cthe cbuffer cacid c(HA) cwith ca cstrong cbase.
2. cPartially ctitrating cthe cbuffer cbase c(A-) cwith ca cstrong cacid.
3. cBy ccombining cthe cweak cbuffer cacid c(HA) cand ca csalt cof cthe cbuffer cacid cin ca cknown cratio.
Buffer ccontaining csufficient cconcentrations cof cboth cHA cand cA- c- cAnswer c- ccan cresist cdrastic cchanges cin
cthe cpH cupon caddition cof csmall camounts cof cstrong cacid cor cstrong cbase. c
This cis cbecause cbuffers cwill creact cwith ca cstrong cacid cto cgenerate cHA, cor cwith ca cstrong cbase cto cgenerate
cA-. cThe cbuffer cratio cwill cchange cdepending con cthe camount cof cstrong cacid cor cstrong cbase cadded. cThe
cpH cwill cnot cchange cdrastically cuntil ceither cacid cor cbase ccomponent cof cthe cbuffer cis cconsumed.
Buffer ccapacity c- cAnswer c- cThe camount cof cstrong cacid cor cstrong cbase cthat ccan cbe cconsumed cby cthe
cbuffer cbefore cthe cpH cchanges cdramatically. c
-The ccapacity cof cthe cbuffer cto cconsume cacid cis climited cby cthe cconcentration cof cA- cpresent cin cthe
coriginal cbuffer, cand cthe ccapacity cof cthe cbuffer cto cconsume cbase cin climited cby cthe cconcentration cof cHA
cpresent cin cthe coriginal cbuffer.
monoprotic cacid c- cAnswer c- cAn cacid cthat ccan conly cdonate cone cproton, cand cis conly cuseful cas ca cbuffer
cover ca csmall cpH crange.
The cpurpose cof ca cbuffer: c- cAnswer c- cto cmaintain ca crelatively cconstant cpH cin ca csolution
Buffers care ceffective cover ca crange cof c- cAnswer c- cpH c= cpKa c+/- c1.0
And Answers
pH cof ca cbuffer csolution cdepends con c- cAnswer c- cthe cpKa cof cthe cacid cand cthe cratio c[A-]/[HA].
Henderson-Hasselbalch cequation c- cAnswer c- cpH c= cpKa c+ clog([A-]/[HA])
This cequation cis cused cto cdetermine cthe cpH cof ca cbuffer csolution.
Buffer c- cAnswer c- can caqueous csolution cof ca cWEAK cacid c(HA) cand cits cconjugate cbase c(A-). cThey ccan cbe
cmade cin cthree cways:
1. cPartially ctitrating cthe cbuffer cacid c(HA) cwith ca cstrong cbase.
2. cPartially ctitrating cthe cbuffer cbase c(A-) cwith ca cstrong cacid.
3. cBy ccombining cthe cweak cbuffer cacid c(HA) cand ca csalt cof cthe cbuffer cacid cin ca cknown cratio.
Buffer ccontaining csufficient cconcentrations cof cboth cHA cand cA- c- cAnswer c- ccan cresist cdrastic cchanges cin
cthe cpH cupon caddition cof csmall camounts cof cstrong cacid cor cstrong cbase. c
This cis cbecause cbuffers cwill creact cwith ca cstrong cacid cto cgenerate cHA, cor cwith ca cstrong cbase cto cgenerate
cA-. cThe cbuffer cratio cwill cchange cdepending con cthe camount cof cstrong cacid cor cstrong cbase cadded. cThe
cpH cwill cnot cchange cdrastically cuntil ceither cacid cor cbase ccomponent cof cthe cbuffer cis cconsumed.
Buffer ccapacity c- cAnswer c- cThe camount cof cstrong cacid cor cstrong cbase cthat ccan cbe cconsumed cby cthe
cbuffer cbefore cthe cpH cchanges cdramatically. c
-The ccapacity cof cthe cbuffer cto cconsume cacid cis climited cby cthe cconcentration cof cA- cpresent cin cthe
coriginal cbuffer, cand cthe ccapacity cof cthe cbuffer cto cconsume cbase cin climited cby cthe cconcentration cof cHA
cpresent cin cthe coriginal cbuffer.
monoprotic cacid c- cAnswer c- cAn cacid cthat ccan conly cdonate cone cproton, cand cis conly cuseful cas ca cbuffer
cover ca csmall cpH crange.
The cpurpose cof ca cbuffer: c- cAnswer c- cto cmaintain ca crelatively cconstant cpH cin ca csolution
Buffers care ceffective cover ca crange cof c- cAnswer c- cpH c= cpKa c+/- c1.0
