Other Classification of Reactions

Water as a Solvent

_______________ – substance being dissolved

_______________ – substance doing the dissolvingWater is the universal solvent –

_______________ _______________

Water as a Solvent

Some solvents play a _______________ role – disperse dissolved substances into individual molecules but doing nothing else.

Water plays an _______________ role – interacts strongly with substances and in some cases, reacting with other substances.

Water as a Solvent

2 major factors that contribute to water’s ability to act as a solvent:The distribution of the bonding

_______________Overall _______________

Water as a Solvent

Water is _______________ bonded – shared electrons between nonmetals and nonmetals.Even in the sharing of electrons, one element

can have more of an _______________ for the electrons than another element.

Atoms of the same element that are covalently bonded share equally.

Water as a Solvent

Oxygen has a _______________ attraction for the electrons than hydrogen.

In water, the electrons spend more time closer to the oxygen atom than the hydrogen atom.

Water as a Solvent When a molecule has unequal sharing of

electrons, we call it a _______________ molecule.

When a molecule has equal sharing of electrons, we call it a _______________ molecule.

When there is a complete electron transfer, as in ionic bonding, it is called an ionic bond or _______________ compound.

Water as a Solvent

Water has unequal sharing of electrons, therefore, it is a _______________ _______________.

Water as a Solvent

With an ionic solid in water, the oppositely charged ions are held next to each other by _______________ attraction.

Water separates the ions by replacing that attraction with one between the water molecules and the ions.

The dissolution of an ionic compound.

The negative ends of the water molecules are attracted to the positive _______________, and the positive ends of the water molecules are attracted to the negative _______________.

The attraction becomes great enough that the ions separate (_______________) and become _______________ (surrounded by solvent molecules).

Water as a Solvent

Water as a Solvent

When an ionic compound dissolves, an important change occurs in the solution.

The solution becomes electrically conductive.

Water as a Solvent

Water as a Solvent

A substance that conducts a current when dissolved in water is an _______________.

Soluble ionic compounds are _______________ electrolytes because they dissociate completely.

Water as a Solvent

Some compounds only dissociate partially and are called _______________ electrolytes.

Some compounds do not dissociate at all and are called _______________Covalently bonded compounds are

_______________ – no ions ever form

Solubility Rules

Those substances that are soluble and form ions completely:

All ammonium (NH4+) compounds, all Alkali

metals, all nitrates (NO3-), all chlorates (ClO3

-), all acetates (C2H3O2

- - with the exception of acetic acid)

Solubility Rules

All chlorides (Cl-), bromides (Br -), and

iodides (-) with the exception of Hg2+, Ag+, and Pb2+

All sulfates (SO42-) with the exception of

Sr2+, Ba2+, Hg2+, Pb2+

Strong Acids – HCl, HNO3, HClO3, HClO4, H2SO4, HBr, H

Solubility Rules

Those that are not soluble:

All hydroxides (OH-) except calcium (Ca2+), barium (Ba2+), and strontium (Sr2+)

All phosphates (PO43-), carbonates (CO3

2-), chromates (CrO4

2-), oxalates (C2O42-), sulfides

(S2-), fluorides (F-), and oxides (O2-) All molecules (nonmetal-nonmetal compounds),

solids, liquids, and gases.

Using the Solubility Rules

_______________ Equations – reveals the least about the species in solution and shows all the reactants and products in the equation.

_______________ Equations – shows all the soluble and insoluble substances with spectator ions eliminated.

Using the Solubility Rules

_______________– those that are in the equation but remain unchanged and are not involved in the actual chemical change.

Writing Net Ionic Equations

1. Write the molecular equation first. 2. Dissociate all substances that are

soluble. 3. Cancel out any spectator ions. 4. Rewrite the final net ionic equation

(NIE)

Precipitation Reactions

Two soluble ionic compounds react to form an insoluble product – _______________.

The reaction of Pb(NO3)2 & Na

Pb(NO3)2 + Na NaNO3 + Pb2

Pb(NO3)2 and Na are soluble and will form ions of Pb2+, NO3

-, Na+ and -

NaNO3 is soluble and will form ions of Na+ and NO3-

Pb2 is not soluble and will not form ions

Pb2+ + NO3- + Na+ + - Na+ + NO3

- + Pb2

Cancel out the spectator ions – Na+ and the NO3-

Pb2+ + - Pb2 is the final net ionic equation

This solid formed in this reaction is the Pb2, as can be seen from the precipitation reaction and the net ionic equation written.