 # IONS IN AQUEOUS SOLUTIONS AND COLLIGATIVE PROPERTIES.

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IONS IN AQUEOUS SOLUTIONS AND COLLIGATIVE PROPERTIES

COMPOUNDS IN AQUEOUS SOLUTION

What is dissociation?

Dissociation – solid ionic compound separating into ions

In this case there are 3 moles of ions produced.

Dissociation – solid ionic compound separating into ions CuSO 4 (s)  Cu 2+ (aq) + SO 4 2- (aq) 1 mole of solid produces 2 moles of ions

Example 1: What kinds of ions will be formed when the following solids are added to water? How many moles?  0.5 moles of Ba(NO 3 ) 2 (s)

Example 1: What kinds of ions will be formed when the following solids are added to water? How many moles?  2.1 moles of FeCl 3 (s)

Example 1: What kinds of ions will be formed when the following solids are added to water? How many moles?  5.0 moles of Na 2 CO 3 (s)

Example 1: What kinds of ions will be formed when the following solids are added to water? How many moles?  1.0 moles of (NH 4 ) 3 PO 4 (s)

Double displacement reactions may happen when 2 ionic solutions are mixed. One driving force is the formation of a precipitate.

Double displacement reactions may happen when 2 ionic solutions are mixed. One driving force is the formation of a precipitate. A precipitate forms when the ions are more strongly attracted to each other than the solvent they are dissolved in. The precipitate will be an insoluble compound. If there is no insoluble compound formed (all the products are soluble) then no reaction happens.

Example 2: Decide whether the following are soluble or insoluble in water:  AgNO 3  KCl  FePO 4  Mn(OH) 2  Na 2 CO 3  NiO  PbI 2  CoS  Zn(ClO 4 ) 2

When a double displacement reaction occurs with 2 ionic solutions, the ions that do not react are called the “spectator ions”. The ions that do react can then be written as a net ionic equation.

When lead (II) nitrate mixes with sodium hydroxide, a precipitate of lead (II) hydroxide forms. Write the net ionic equation for the reaction.

Pb(NO 3 ) 2 (aq) + NaOH(aq) 

When lead (II) nitrate mixes with sodium hydroxide, a precipitate of lead (II) hydroxide forms. Write the net ionic equation for the reaction. Pb(NO 3 ) 2 (aq) + NaOH(aq)  Pb 2+ (aq) + 2NO 3 1- (aq) + Na 1+ (aq) + OH 1- (aq) 

When lead (II) nitrate mixes with sodium hydroxide, a precipitate of lead (II) hydroxide forms. Write the net ionic equation for the reaction. Pb(NO 3 ) 2 (aq) + NaOH(aq)  Pb 2+ (aq) + 2NO 3 1- (aq) + Na 1+ (aq) + OH 1- (aq)  Pb(OH) 2 (s) + Na 1+ (aq) + 2NO 3 1- (aq)

When lead (II) nitrate mixes with sodium hydroxide, a precipitate of lead (II) hydroxide forms. Write the net ionic equation for the reaction. Pb(NO 3 ) 2 (aq) + NaOH(aq)  Pb 2+ (aq) + 2NO 3 1- (aq) + Na 1+ (aq) + OH 1- (aq)  Pb(OH) 2 (s) + Na 1+ (aq) + 2NO 3 1- (aq)

When lead (II) nitrate mixes with sodium hydroxide, a precipitate of lead (II) hydroxide forms. Write the net ionic equation for the reaction. Pb(NO 3 ) 2 (aq) + NaOH(aq)  Pb 2+ (aq) + 2NO 3 1- (aq) + Na 1+ (aq) + OH 1- (aq)  Pb(OH) 2 (s) + Na 1+ (aq) + 2NO 3 1- (aq) Net ionic equation = Pb 2+ (aq) + 2OH 1- (aq)  Pb(OH) 2 (s)

Example 3: Write net ionic equations for the following and identify the spectator ions: NaBr(aq) + AgNO 3 (aq) 

Example 3: Write net ionic equations for the following and identify the spectator ions: MgSO 4 (aq) + (NH 4 ) 2 CO 3 (aq) 

Example 4: Will a reaction happen if the following solutions are mixed? If so, write the net ionic equation:  KCl(aq) + NaNO 3 (aq)

Example 4: Will a reaction happen if the following solutions are mixed? If so, write the net ionic equation:  FeCl 3 (aq) + KOH(aq)

Example 4: Will a reaction happen if the following solutions are mixed? If so, write the net ionic equation:  NH 4 NO 3 (aq) + Pb(C 2 H 3 O 2 ) 2 (aq)

Example 4: Will a reaction happen if the following solutions are mixed? If so, write the net ionic equation:  SnCl 2 (aq) + NaOH(aq)

Example 4: Will a reaction happen if the following solutions are mixed? If so, write the net ionic equation:  NaOH(aq) + CuCl 2 (aq)

What is ionization?

Ionization – a covalently bonded compound (molecule) forms ions when dissolved in a solution. The attraction between the solvent particles and the solute is stronger than the attraction within the solvent particles.

Ionization – a covalently bonded compound (molecule) forms ions when dissolved in a solution. The attraction between the solvent particles and the solute is stronger than the attraction within the solvent particles. The most common examples are acids: H 2 SO 4 (aq) + H 2 O(l) 

Ionization – a covalently bonded compound (molecule) forms ions when dissolved in a solution. The attraction between the solvent particles and the solute is stronger than the attraction within the solvent particles. The most common examples are acids: H 2 SO 4 (aq) + H 2 O(l)  H 3 O + (aq) + HSO 4 1- (aq)

Ionization – a covalently bonded compound (molecule) forms ions when dissolved in a solution. The attraction between the solvent particles and the solute is stronger than the attraction within the solvent particles. The most common examples are acids: H 2 SO 4 (aq) + H 2 O(l)  H 3 O + (aq) + HSO 4 1- (aq) HSO 4 1- (aq) + H 2 O(l) 

Ionization – a covalently bonded compound (molecule) forms ions when dissolved in a solution. The attraction between the solvent particles and the solute is stronger than the attraction within the solvent particles. The most common examples are acids: H 2 SO 4 (aq) + H 2 O(l)  H 3 O + (aq) + HSO 4 1- (aq) HSO 4 1- (aq) + H 2 O(l)  H 3 O + (aq) + SO 4 2- (aq)

Ionization – a covalently bonded compound (molecule) forms ions when dissolved in a solution. The attraction between the solvent particles and the solute is stronger than the attraction within the solvent particles. The most common examples are acids: H 2 SO 4 (aq) + H 2 O(l)  H 3 O + (aq) + HSO 4 1- (aq) HSO 4 1- (aq) + H 2 O(l)  H 3 O + (aq) + SO 4 2- (aq) H 3 O + = hydronium ion

Ionization – a covalently bonded compound (molecule) forms ions when dissolved in a solution. H 3 O + = hydronium ion Even more importantly, a few water molecules (1 x 10 -7 moles per liter) will forms hydronium ions along with hydroxide ions.

How does a strong electrolyte compare to a weak electrolyte?

Strong electrolyte – produces many ions in water Weak electrolyte – produces few ions in water This is based on the degree of ionization or dissociation that occurs.

Strong electrolyte – produces many ions in water Weak electrolyte – produces few ions in water This is based on the degree of ionization or dissociation that occurs. A compound that has 100% ionization/dissociation will be a strong electrolyte. A compound that has low ionization/dissociation will be a weak electrolyte.

Strong electrolyte – produces many ions in water Weak electrolyte – produces few ions in water This is based on the degree of ionization or dissociation that occurs. A compound that has 100% ionization/dissociation will be a strong electrolyte. A compound that has low ionization/dissociation will be a weak electrolyte. This will be represented by the quantitative values K a, K b, K sp, K w, and others.