Chemical Reactions: Aqueous Ionic Lecture 10
Chemical reactions everywhere.
Reactions in gaseous phase:
Reactions in aqueous phase:
Our chemistry is merely its oxygenic/aqueous version. Because water is the predominant solvent, and oxygen is the active c...
Why is water so remarkable solvent? <ul><li>It is due to a special distribution of the bonding electrons in its molecules....
A molecule is polar if distribution of positive and negative charges on the various atoms is non-uniform.
Water molecule is polar <ul><li>Because of its bent shape, and </li></ul><ul><li>Because of having polar bonds. </li></ul>
In an ionic solid, the oppositely charged ions are held next to each other by electrostatic attraction.
Water separates the ions by replacing that attraction with one between the water molecules and the ions.
The separated ions become solvated.
If an ionic solid is insoluble, the electrostatic attraction among its ions is greater than the attraction between its ion...
However, even s.c. insoluble substances do dissolve. Just a little. Solubility of NaCl in H 2 O at 20°C = 365 g/L Solubili...
When an ionic compound dissolves, the electric conductivity increases.
The bulb is lit because of current, the current flows because charged particles move, the charged particles are cations an...
An electrolyte is a substance that conducts a current when dissolved in water.
How salts dissociate (simplified): <ul><li>KBr (s)    K + (aq)  + Br - (aq) </li></ul><ul><li>NaNO 3(s)    Na + (aq)  ...
The formula of the compound tells the number of moles of different ions that result when the compound dissolves.
A sample problem on determining moles of ions in aqueous ionic solutions.
Most covalent compounds do not dissociate into ions. Even if they dissolve.
Most covalent compounds do not conduct electrical current. Therefore, they are nonelectrolytes.
A small group of covalent compounds interact with water strongly and their molecules do dissociate into ions. In aqueous s...
How acids dissociate (simplified): <ul><li>HBr (g)    H + (aq)  + Br - (aq) </li></ul><ul><li>HNO 3(l)    H + (aq)  + ...
A sample problem on determining the molarity of H +  ions in an aqueous solution of an acid.
Water interacts strongly with many ions, but most strongly with the hydrogen cation H + . A very unusual species. Actually...
H +  is small but powerful, carrying a full positive charge concentrated in a tiny volume. Very attractive, following Coul...
How acids dissociate: <ul><li>HBr (g)  + H 2 O (l)    H 3 O + (aq)  + Br - (aq) </li></ul><ul><li>HNO 3(l)  + H 2 O (l) ...
Equations to represent aqueous ionic reactions: <ul><li>Molecular:  NaBr (aq)   + AgNO 3 (aq)    AgBr (s)  + NaBr   (aq)...
Equations to represent aqueous ionic reactions: <ul><li>Molecular:  BaCl 2 (aq)   + FeSO 4 (aq)    BaSO 4(s)  + FeCl 2(a...
THE END
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Lecture10221

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Lecture10221

  1. 1. Chemical Reactions: Aqueous Ionic Lecture 10
  2. 2. Chemical reactions everywhere.
  3. 3. Reactions in gaseous phase:
  4. 4. Reactions in aqueous phase:
  5. 5. Our chemistry is merely its oxygenic/aqueous version. Because water is the predominant solvent, and oxygen is the active component of the Earth’s atmosphere.
  6. 6. Why is water so remarkable solvent? <ul><li>It is due to a special distribution of the bonding electrons in its molecules. </li></ul><ul><li>It is due to a special overall shape of its molecules. </li></ul>
  7. 7. A molecule is polar if distribution of positive and negative charges on the various atoms is non-uniform.
  8. 8. Water molecule is polar <ul><li>Because of its bent shape, and </li></ul><ul><li>Because of having polar bonds. </li></ul>
  9. 9. In an ionic solid, the oppositely charged ions are held next to each other by electrostatic attraction.
  10. 10. Water separates the ions by replacing that attraction with one between the water molecules and the ions.
  11. 11. The separated ions become solvated.
  12. 12. If an ionic solid is insoluble, the electrostatic attraction among its ions is greater than the attraction between its ions and water molecules.
  13. 13. However, even s.c. insoluble substances do dissolve. Just a little. Solubility of NaCl in H 2 O at 20°C = 365 g/L Solubility of AgCl in H 2 O at 20°C = 365 g/L
  14. 14. When an ionic compound dissolves, the electric conductivity increases.
  15. 15. The bulb is lit because of current, the current flows because charged particles move, the charged particles are cations and anions.
  16. 16. An electrolyte is a substance that conducts a current when dissolved in water.
  17. 17. How salts dissociate (simplified): <ul><li>KBr (s)  K + (aq) + Br - (aq) </li></ul><ul><li>NaNO 3(s)  Na + (aq) + NO 3 - (aq) </li></ul><ul><li>K 2 S (s)  2K + (aq) + S 2- (aq)  </li></ul><ul><li>ZnI 2(s)  Zn 2+ (aq) + 2I - (aq)  </li></ul><ul><li>Al(NO 3 ) 3 (s)  Al 3+ (aq) + 3NO - 3(aq) </li></ul><ul><li>Cr 2 (SO 4 ) 3 (s)  2Cr 3+ (aq) + 3SO 2- 4(aq)  </li></ul><ul><li> </li></ul>
  18. 18. The formula of the compound tells the number of moles of different ions that result when the compound dissolves.
  19. 19. A sample problem on determining moles of ions in aqueous ionic solutions.
  20. 20. Most covalent compounds do not dissociate into ions. Even if they dissolve.
  21. 21. Most covalent compounds do not conduct electrical current. Therefore, they are nonelectrolytes.
  22. 22. A small group of covalent compounds interact with water strongly and their molecules do dissociate into ions. In aqueous solution, these substances are all acids.
  23. 23. How acids dissociate (simplified): <ul><li>HBr (g)  H + (aq) + Br - (aq) </li></ul><ul><li>HNO 3(l)  H + (aq) + NO 3 - (aq) </li></ul><ul><li>HCl (g)  H + (aq) + Cl - (aq)  </li></ul><ul><li>H 2 SO 4 (l)  2H + (aq) + SO 2- 4(aq)  </li></ul><ul><li> </li></ul>
  24. 24. A sample problem on determining the molarity of H + ions in an aqueous solution of an acid.
  25. 25. Water interacts strongly with many ions, but most strongly with the hydrogen cation H + . A very unusual species. Actually, it is a proton!
  26. 26. H + is small but powerful, carrying a full positive charge concentrated in a tiny volume. Very attractive, following Coulomb’s law.
  27. 27. How acids dissociate: <ul><li>HBr (g) + H 2 O (l)  H 3 O + (aq) + Br - (aq) </li></ul><ul><li>HNO 3(l) + H 2 O (l)  H 3 O + (aq) + NO 3 - (aq) </li></ul><ul><li>HCl (g) + H 2 O (l)  H 3 O + (aq) + Cl - (aq)  </li></ul><ul><li>H 2 SO 4 (l) + 2H 2 O (l)  2H 3 O + (aq) + SO 2- 4(aq) </li></ul><ul><li>H 3 O + is called hydronium ion. It can be represented as (H 2 O)H + </li></ul><ul><li> </li></ul>
  28. 28. Equations to represent aqueous ionic reactions: <ul><li>Molecular: NaBr (aq) + AgNO 3 (aq)  AgBr (s) + NaBr (aq) </li></ul><ul><li>Total ionic: Na + (aq) + Br - (aq) + Ag + (aq) + NO - 3 (aq)  AgBr (s) + Na + (aq) + Br - (aq) </li></ul><ul><li>Net ionic: Ag + (aq) + Br - (aq)  AgBr (s) </li></ul>
  29. 29. Equations to represent aqueous ionic reactions: <ul><li>Molecular: BaCl 2 (aq) + FeSO 4 (aq)  BaSO 4(s) + FeCl 2(aq) </li></ul><ul><li>Total ionic: Ba 2+ (aq) + 2Cl - (aq) + Fe 2+ (aq) + SO 2- 4 (aq)  BaSO 4(s) + Fe 2+ (aq) + 2Cl - (aq) </li></ul><ul><li>Net ionic: Ba 2+ (aq) + SO 2- 4 (aq)  BaSO 4(s) </li></ul>
  30. 30. THE END

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