Page 1 Notes: Water, Ionic/Covalent, and Electrolyte Concepts

Dissolution in Water: Ionic vs Covalent Substances

Water as a solvent relies on its polarity and hydrogen bonding to dissolve many substances.
These forces in the water will pull cations and anions apart to dissolve some ionic compounds.
Covalent substances do not have ions, so they cannot be ionized and are typically non-electrolytes in water.

When ionic compounds dissolve, they dissociate into ions in solution: the solid salt breaks into cations and anions surrounded by water molecules.
The extent of dissociation determines whether the substance is a good conductor of electricity in solution.
The activity described in the transcript involves drawing water and considering how ions separate when salts dissolve.

Draw a water molecule:
- H2O with a bent shape (approx. 104.5° between O–H bonds).
- Label hydrogen atoms with the partial positive charge symbol (δ+) and the oxygen with the partial negative charge symbol (δ−).
This polarity is what drives ion separation in aqueous solutions.

Ionic substances: compounds that produce ions in water (salts, strong electrolytes) and typically dissolve to yield cations and anions.
Covalent substances: molecules that do not produce ions in water (non-electrolytes) and may dissolve as intact molecules.
Beaker labeling task (from the transcript): label each beaker above as ionic or covalent.
Circle the beakers that will conduct electricity (ionic solutions, especially when ions are present in solution).

Sodium acetate: ext{NaC}2 ext{H}3 ext{O}2 (s) ightarrow ext{Na}^+(aq) + ext{C}2 ext{H}3 ext{O}2^-(aq)
Calcium nitrate: ext{Ca(NO}3)2 (s)
ightarrow ext{Ca}^{2+}(aq) + 2 ext{NO}_3^-(aq)
These are ionic compounds and, when dissolved, typically act as strong electrolytes (they fully dissociate into ions).
Non-electrolyte examples (covalent substances): dissolve in water but do not form ions; they do not conduct electricity in solution.

Electrolyte: a substance that produces ions in solution and conducts electricity.
Strong electrolyte: dissolves in water to yield ions completely, resulting in high electrical conductivity.
Nonelectrolyte: dissolves in water as molecules but does not produce ions; little to no electrical conductivity.
Beaker activity goal: identify which beakers contain ionic substances (strong electrolytes) versus covalent nonelectrolytes, and circle those that conduct electricity.

General ionic dissolution (example salts):
- ext{Salt}(s)
  ightarrow ext{Cation}^{+}(aq) + ext{Anion}^{-}(aq)
- The specific stoichiometry depends on the salt.
For calcium nitrate:
- ext{Ca(NO}3)2 (s)
  ightarrow ext{Ca}^{2+}(aq) + 2 ext{NO}_3^-(aq)
For sodium acetate:
- ext{NaC}2 ext{H}3 ext{O}2 (s) ightarrow ext{Na}^+(aq) + ext{C}2 ext{H}3 ext{O}2^-(aq)
These reactions illustrate complete dissociation typical of strong electrolytes.

Conductivity in solution depends on the presence and concentration of mobile ions.
Strong electrolytes (fully dissociated) conduct electricity well in solution.
Nonelectrolytes (no ions) do not conduct electricity in solution.
The ability to conduct electricity is a practical diagnostic for whether a substance in water behaves as an electrolyte.

Polarity and solvation: Water’s dipole stabilizes ions via ion-dipole interactions, aiding dissolution.
Ionization vs. molecular presence: Ionic compounds form ions in solution; covalent compounds typically don’t unless they ionize (e.g., strong acids/bases in some contexts, which is beyond the transcript’s explicit examples).
Stoichiometry and charge balance: Dissociation produces charges that enable current flow; reactions must balance charges on both sides.

Electrolyte: substance that produces ions in solution and conducts electricity.
Strong electrolyte: dissociates completely in water, yielding a large number of ions.
Nonelectrolyte: does not produce ions in water, leading to little or no conductivity.
Ionic compound: compound that dissociates into ions in water (e.g., salts like NaCl, NaC2H3O2, Ca(NO3)2).
Covalent compound: compound composed of covalent bonds; generally forms molecules, not ions, in solution.

Water dissolves many ionic compounds by dissociating them into cations and anions.
Covalent compounds may dissolve but do not form ions in solution and are typically nonelectrolytes.
Strong electrolytes dissolve completely and conduct electricity; nonelectrolytes do not conduct electricity.
Examples from the transcript include:
- ext{NaC}2 ext{H}3 ext{O}2 (s) ightarrow ext{Na}^+(aq) + ext{C}2 ext{H}3 ext{O}2^-(aq)
- ext{Ca(NO}3)2 (s)
  ightarrow ext{Ca}^{2+}(aq) + 2 ext{NO}_3^-(aq)
Practical activity involves labeling beakers as ionic or covalent and circled conductive solutions.