WCLN - Ionization of Water - Chemistry
31.2 هزار بار بازدید -
11 سال پیش
-
Shows how water ionizes to
Shows how water ionizes to form hydronium and hydroxide ions
Gives the ionization equation for water
Defines Kw and shows the Kw expression
Defines neutral, acidic, and basic solutions
http://www.BCLearningNetwork.com.
0:00water is usually thought of as a
0:05nonconductor however very sensitive
0:07devices can detect some conductivity and
0:10water no matter how period is even very
0:14pure distilled water contains some ions
0:16why is this so in any sample of pure
0:20water almost all of the water molecules
0:22remain as neutral water molecules and
0:24don't react chemically with each other
0:27however about two out of every five
0:29hundred and fifty six million water
0:31molecules will react chemically with
0:34each other will show two of them here
0:36but they're bonding and non-bonding
0:38electrons
0:40the purple one will act as an acid and
0:43the blue one will act as a base
0:46the hydrogen atom breaks away from the
0:49water on the left and leaves it shared
0:51electron behind
0:53because it has lost an electron requires
0:56a positive charge becoming an H+ ion or
0:59proton
1:01because the o.h is gained an electron it
1:04requires a negative charge and it's
1:06called the hydroxide ion
1:09with the formula or h minus the proton
1:12moves to a nonbonding electron pair on
1:15the other water molecule will change its
1:18color to blue
1:19the positive charge is now distributed
1:21over the whole iron instead of just
1:24being on the H that it came with
1:26this is now a hydronium ion with the
1:29formula h3o plus
1:33the process can be summarized by an
1:35equation when a proton is transferred
1:38from one water molecule to another the
1:41water on the Left gains a proton to
1:43become a hydronium ion and the water on
1:46the right loses a proton to become a
1:48hydroxide ion
1:50however when a hydronium ion in water
1:52encounters a hydroxide ion the reverse
1:55reaction can also occur where a proton
1:58is transferred from the hydronium ion to
2:01the hydroxide
2:03forming two molecules of water because
2:06both the forward and reverse reactions
2:08continuously occur this is an
2:11equilibrium so we use a double arrow
2:13here instead of writing these two
2:16separate water molecules we can combine
2:18them to show them simply as two water
2:21molecules
2:23remove this arrow over a bit this
2:26equation is very important equation to
2:28know it's called the ionization of water
2:31equation
2:32sometimes it's called the self
2:34ionization of water because water acts
2:37as both the acid and the base in
2:40chemistry 12 we refer to it simply as
2:43the ionization of water
2:45at a normal room temperature of 25
2:47degrees the reactant liquid water is
2:50highly favorite to illustrate this we
2:53show there's more reactants and products
2:56the relative sizes of the letters here
2:58are very qualitative and nowhere near to
3:01scale the concentration of hydronium and
3:04hydroxide ions are only about two
3:06billions that of water
3:09the KQ expression for this reaction is
3:11equal to the concentration of hydronium
3:13times the concentration of hydroxide
3:16because the water is a liquid it is not
3:19included in the KQ expression
3:22because this equilibrium constant is
3:24specifically concerned with water we
3:27change the symbol from KQ to kW kW is
3:32called the ionization constant of water
3:35the value for KW his
3:38temperature-dependent at 25 degrees the
3:41value is 1 times 10 to the negative 14
3:43is very important to remember the value
3:47of K W is 1 times 10 to the negative 14
3:50only at 25 degrees celsius and no other
3:54temperature
3:56but KW is always equal to the
3:58concentration of hydronium times the
4:00concentration of hydroxide at any
4:03temperature for which water is in the
4:05liquid state because all equal solutions
4:08contain water and all water ionizers to
4:11form some hydronium and hydroxide ions
4:14we know that all aqueous solutions
4:17contain some hydronium and some
4:19hydroxide ions by definition for any
4:22aqueous solution if the concentration of
4:25hydronium is equal to the concentration
4:27of hydroxide the solution is set to be
4:30neutral and if the concentration of
4:32hydronium is greater than the
4:34concentration of hydroxide the solution
4:37is set to be acidic and if the
4:39concentration of hydronium is less than
4:41the concentration of hydroxide solution
4:44is set to be basic these are the
4:47definitions will use for neutral acidic
4:50and basic solutions you must make sure
4:52that you know these
Gives the ionization equation for water
Defines Kw and shows the Kw expression
Defines neutral, acidic, and basic solutions
http://www.BCLearningNetwork.com.
0:00water is usually thought of as a
0:05nonconductor however very sensitive
0:07devices can detect some conductivity and
0:10water no matter how period is even very
0:14pure distilled water contains some ions
0:16why is this so in any sample of pure
0:20water almost all of the water molecules
0:22remain as neutral water molecules and
0:24don't react chemically with each other
0:27however about two out of every five
0:29hundred and fifty six million water
0:31molecules will react chemically with
0:34each other will show two of them here
0:36but they're bonding and non-bonding
0:38electrons
0:40the purple one will act as an acid and
0:43the blue one will act as a base
0:46the hydrogen atom breaks away from the
0:49water on the left and leaves it shared
0:51electron behind
0:53because it has lost an electron requires
0:56a positive charge becoming an H+ ion or
0:59proton
1:01because the o.h is gained an electron it
1:04requires a negative charge and it's
1:06called the hydroxide ion
1:09with the formula or h minus the proton
1:12moves to a nonbonding electron pair on
1:15the other water molecule will change its
1:18color to blue
1:19the positive charge is now distributed
1:21over the whole iron instead of just
1:24being on the H that it came with
1:26this is now a hydronium ion with the
1:29formula h3o plus
1:33the process can be summarized by an
1:35equation when a proton is transferred
1:38from one water molecule to another the
1:41water on the Left gains a proton to
1:43become a hydronium ion and the water on
1:46the right loses a proton to become a
1:48hydroxide ion
1:50however when a hydronium ion in water
1:52encounters a hydroxide ion the reverse
1:55reaction can also occur where a proton
1:58is transferred from the hydronium ion to
2:01the hydroxide
2:03forming two molecules of water because
2:06both the forward and reverse reactions
2:08continuously occur this is an
2:11equilibrium so we use a double arrow
2:13here instead of writing these two
2:16separate water molecules we can combine
2:18them to show them simply as two water
2:21molecules
2:23remove this arrow over a bit this
2:26equation is very important equation to
2:28know it's called the ionization of water
2:31equation
2:32sometimes it's called the self
2:34ionization of water because water acts
2:37as both the acid and the base in
2:40chemistry 12 we refer to it simply as
2:43the ionization of water
2:45at a normal room temperature of 25
2:47degrees the reactant liquid water is
2:50highly favorite to illustrate this we
2:53show there's more reactants and products
2:56the relative sizes of the letters here
2:58are very qualitative and nowhere near to
3:01scale the concentration of hydronium and
3:04hydroxide ions are only about two
3:06billions that of water
3:09the KQ expression for this reaction is
3:11equal to the concentration of hydronium
3:13times the concentration of hydroxide
3:16because the water is a liquid it is not
3:19included in the KQ expression
3:22because this equilibrium constant is
3:24specifically concerned with water we
3:27change the symbol from KQ to kW kW is
3:32called the ionization constant of water
3:35the value for KW his
3:38temperature-dependent at 25 degrees the
3:41value is 1 times 10 to the negative 14
3:43is very important to remember the value
3:47of K W is 1 times 10 to the negative 14
3:50only at 25 degrees celsius and no other
3:54temperature
3:56but KW is always equal to the
3:58concentration of hydronium times the
4:00concentration of hydroxide at any
4:03temperature for which water is in the
4:05liquid state because all equal solutions
4:08contain water and all water ionizers to
4:11form some hydronium and hydroxide ions
4:14we know that all aqueous solutions
4:17contain some hydronium and some
4:19hydroxide ions by definition for any
4:22aqueous solution if the concentration of
4:25hydronium is equal to the concentration
4:27of hydroxide the solution is set to be
4:30neutral and if the concentration of
4:32hydronium is greater than the
4:34concentration of hydroxide the solution
4:37is set to be acidic and if the
4:39concentration of hydronium is less than
4:41the concentration of hydroxide solution
4:44is set to be basic these are the
4:47definitions will use for neutral acidic
4:50and basic solutions you must make sure
4:52that you know these
11 سال پیش
در تاریخ 1392/11/23 منتشر شده
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