Home >
Community >
What is the difference between stability and lability, and what actually makes a compound labile, non-labile and inert?
Upvote
11
Downvote
+ Chemical reactions
+ Chemistry
+ Organic chemistry
+ Stability
Posted by
Matthew Arslan
What is the difference between stability and lability, and what actually makes a compound labile, non-labile and inert?
Labile is not as much a thing that compounds are, even though strictly speaking it’s an adjective by definition[1] and is used that way. Let’s discuss this starting on those terms.
When you think of water, you think of it as something which is stable- if you have a container filled with water, and you seal it up for millions of years, it’s still the same exact water, at least to your limited perception. But if you were able to mark, to label, every proton in the water, you would find that millions of years later almost none of the oxygen atoms have the same paired hydrogen atoms attached to them. In fact, many of the hydrogen atoms might have swapped partners a few times in that period. There’s lots of good experiments that demonstrate that- for example, if I mix deuterium water (D2O) and regular hydrogen water (H2O), and measure the composition of the mixture, it doesn’t take very long before much of the water is a mix of D2O, H2O, and HDO.
Likewise, lots of molecules undergo this change[2], and the protons that exchange for deuterium in solution are called labile protons. Not every proton is labile- the ones attached to oxygen or nitrogen are probably the most readily exchanged, because under acidic or basic conditions (depending on the molecule) you can induce the proton to swap out, and it should be fairly obvious that that kind of exchange happens more readily to, say OH group protons under basic conditions, because the hydroxy group isn’t stable under basic conditions. But there are other protons that are labile as well and subject to the exchange.
Labile is not as much a thing that compounds are, even though strictly speaking it’s an adjective by definition[1] and is used that way. Let’s discuss this starting on those terms.
When you think of water, you think of it as something which is stable- if you have a container filled with water, and you seal it up for millions of years, it’s still the same exact water, at least to your limited perception. But if you were able to mark, to label, every proton in the water, you would find that millions of years later almost none of the oxygen atoms have the same paired hydrogen atoms attached to them. In fact, many of the hydrogen atoms might have swapped partners a few times in that period. There’s lots of good experiments that demonstrate that- for example, if I mix deuterium water (D2O) and regular hydrogen water (H2O), and measure the composition of the mixture, it doesn’t take very long before much of the water is a mix of D2O, H2O, and HDO.
Likewise, lots of molecules undergo this change[2], and the protons that exchange for deuterium in solution are called labile protons. Not every proton is labile- the ones attached to oxygen or nitrogen are probably the most readily exchanged, because under acidic or basic conditions (depending on the molecule) you can induce the proton to swap out, and it should be fairly obvious that that kind of exchange happens more readily to, say OH group protons under basic conditions, because the hydroxy group isn’t stable under basic conditions. But there are other protons that are labile as well and subject to the exchange.
Labile is not as much a thing that compounds are, even though strictly speaking it’s an adjective by definition[1] and is used that way. Let’s discuss this starting on those terms.
When you think of water, you think of it as something which is stable- if you have a container filled with water, and you seal it up for millions of years, it’s still the same exact water, at least to your limited perception. But if you were able to mark, to label, every proton in the water, you would find that millions of years later almost none of the oxygen atoms have the same paired hydrogen atoms attached to them. In fact, many of the hydrogen atoms might have swapped partners a few times in that period. There’s lots of good experiments that demonstrate that- for example, if I mix deuterium water (D2O) and regular hydrogen water (H2O), and measure the composition of the mixture, it doesn’t take very long before much of the water is a mix of D2O, H2O, and HDO.
Likewise, lots of molecules undergo this change[2], and the protons that exchange for deuterium in solution are called labile protons. Not every proton is labile- the ones attached to oxygen or nitrogen are probably the most readily exchanged, because under acidic or basic conditions (depending on the molecule) you can induce the proton to swap out, and it should be fairly obvious that that kind of exchange happens more readily to, say OH group protons under basic conditions, because the hydroxy group isn’t stable under basic conditions. But there are other protons that are labile as well and subject to the exchange.
Labile is not as much a thing that compounds are, even though strictly speaking it’s an adjective by definition[1] and is used that way. Let’s discuss this starting on those terms.
When you think of water, you think of it as something which is stable- if you have a container filled with water, and you seal it up for millions of years, it’s still the same exact water, at least to your limited perception. But if you were able to mark, to label, every proton in the water, you would find that millions of years later almost none of the oxygen atoms have the same paired hydrogen atoms attached to them. In fact, many of the hydrogen atoms might have swapped partners a few times in that period. There’s lots of good experiments that demonstrate that- for example, if I mix deuterium water (D2O) and regular hydrogen water (H2O), and measure the composition of the mixture, it doesn’t take very long before much of the water is a mix of D2O, H2O, and HDO.
Likewise, lots of molecules undergo this change[2], and the protons that exchange for deuterium in solution are called labile protons. Not every proton is labile- the ones attached to oxygen or nitrogen are probably the most readily exchanged, because under acidic or basic conditions (depending on the molecule) you can induce the proton to swap out, and it should be fairly obvious that that kind of exchange happens more readily to, say OH group protons under basic conditions, because the hydroxy group isn’t stable under basic conditions. But there are other protons that are labile as well and subject to the exchange.
More
1