Solubility, Ionic Equations, Dimensional Analysis, The Mole

Chemistry Test 2/26/25

Solubility?

A compound’s ability to dissolve in water

Solute?

A material that is mixed in the solvent; Ex) Sugar added to Tea

Solvent?

A liquid that is part of a solution. Solute is mixed in it; Ex) Water in Tea

Dissolve?

Whole molecules being encased by water, broken into small bits but still identifies as a molecule; general term; Ex) Sugar

Dissociate?

The compound itself breaks apart into individual ions that develop their own properties. Lone ions become conductive and reactive; unique to Ionic compounds. Reactions cannot happen without this; Ex) Salt

Solution?

When Ionic Compounds are added to water

Aqueous?

When Ions are dissociated in water; reactions that occur in water;

Soluble?

Able to dissolve in water

Precipitate?

A solid, non-soluble compound formed as a result of an Ionic compound

• After a reaction, free ions can react to form a solid precipitate

Why are some Ionic compounds insoluble?

• Water is good at breaking apart compounds with its own charges

• Some structures have stronger forces water cant break

• Increased lattice energy due to size of Ions

Which Ions in a solution are the most important?

• The ions that do things, and not all do things

• Spectator ions sit and do nothing, can be cancelled out

• Active ions are involved in a change

Trends in the solubility of a compound?

• Solids are insoluble

• Gas/Liquid/Aqueous are soluble

• Most Alkaline metals are aqueous

• Poly atomic Ions depend on what they’re mixed with

• Transition metals tend to be insoluble

Electrolytes?

Ions that when dissolved in water, dissociate into ions, and can conduct electricity.

Net Ionic Equations?

• Show key ions in a solution and how they change and interact

• A “summary” of what is essentially going through a chemical change

Active Ions?

Undergo a chemical change to form a precipitate

Spectator Ions?

Remain in a solution and do not become a solid precipitate

• Can be cancelled out

Molecular Equation?

Equations that show compounds and may include states of matter

• Only ions that form a precipitate are shown (active ones)

  • Spectator ions are cancelled out from Ionic equation

Ionic Equation?

Equations that show ions and if they are dissociated or precipitated

The Mole?

A set group that counts many small things; Ex) A dozen

• The Mole is 6.022 × 10²³ (Avogadro’s number)which represents the number of atoms in a mole

• Makes ratios between compounds in a equation

• Coefficients represent the numbers of moles

• Moles of different substances can weigh differently

• We can use it as a conversion between moles and atoms (molar mass)

Molar Mass?

Finds us the grams per mole for any compound or element

• Same as the atomic mass

• Units: MM or g/mol

• How to find it

  • Find the atomic mass of each element and multiply by how many atoms of each are there

  • Add all numbers together

Dimensional Analysis?

Changing the units of a number using conversions equivalent to 1 to express a number in different units

• Using the “bridge method”

Bridge Method?

• Help us visually organize numbers with multiple units

• Track cancellations by matching units of the top and bottom of a bridge

• Multiply top numbers

• Divide by bottom numbers

Steps to unit conversions?

1. Identify the starting units of a problem

2. Identify the ending units of a problem

3. Identify necessary conversions

4. Use ratios of units to convert to target

Molar Ratio?

The ratio of compounds in a balanced chemical equation

• The coefficients

• We can relate reactants to products; products to products; reactants to reactants

• Anytime we compare chemicals, we will need this

Why is water a universal solvent?

• It can dissolve more substances than any other naturally occurring liquid