1.5 Solubility of Ionic Compounds

Is it common to find naturally occurring 100% pure H₂O?

• No

Most liquids are classified as being-

Solutions

All solutions are composed of what 2 main parts?

• A solvent

• One or more solutes

Define solvent

• A substance (usually a liquid) that has other substances dissolved in it

Define solute

• A substance (usually a solid)

Using a cup of coffee and sugar, which one is the solution, solvent, solute?

• Solution: the cup with everything in it

• Solvent: coffee

• Solute: sugar

Are solutions hetero or homogenous? Why?

• Homogenous

• There are no visible layers or clumps of the solute

Solutions can have variable _____ of solutes

• Concentrations

Define solubility

• The extent to which a solute will dissolve in a given liquid at a given temperature

If two aqueous solutions are mixed together and there is solids at the bottom of the test tube, what would we call this? What’s another name?

• “Insoluble”

• “A precipitate has formed”

Ionic compounds _____ electrons; molecular compounds _____ electrons”

• “Transfer”

• “Share”

Do ionic compounds and molecular compounds both have an overall charge of zero?

• Yes

Describe salt (NaCl) dissolving in water

• + and - elements in the water attract the NaCl compound

• O₂ in the water attract the Na atoms; H in the water attract the chlorine atoms

• This attraction is stronger NaCl’s bond

• NaCl separates into Na⁺ and Cl^-

• Water’s bonds are strong enough to keep the water molecules together

How does activated charcoal work in our taps at home?

• Contaminated water is filtered through them to become safe treated water

What is activated charcoal and how does it work?

• A carbon compound that has been treated with Oxygen so it can attract impurities

• Act as magnets for ions like chlorine and lead

• Changes ions into precipitates so they can’t filter through

In general, is the element that appears first in a chemical formula the cation or the anion?

• Cation (+)

If CaCl₂ is soluble in water, what letters would we use to describe the state?

• _(aq)

What is a use for Barium Sulphate?

• Used in X-Ray imaging of your lower digestive tract

Is Barium Sulphate soluble in water?

• No

When two aqueous ionic compounds are mixed together in a DD reaction, what two outcomes can occur?

1. Nothing

2. Precipitation (formation of a precipitate)

If two products are both soluble, what happens?

• Nothing

• “No reaction”

• In the formula, on the right side of the arrow you would write “no reaction”

If one or more products in a reaction is insoluble, what happens?

• A solid will form

• “Precipitation”

“When a precipitate forms, its ions are actually causing a chemical change due to-”

• “-their strong attraction to one another”

Net ionic equations depict only what?

• The ions involved in the chemical reaction

What are the steps for ionic equations and net ionic equations?

1. Balance the equation first

2. Separate all aqueous reactants and products into ion- do not separate solids, liquids, or gases. This is the total ionic equation

3. Cross out matches from both sides

4. What remains is the net ionic equation. These are the ions that participate in the chemical reaction

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Define spectator ion

• An ion that does not take part in the chemical reaction and is found in the solution both before and after the reaction

Define net ionic equation

• Chemical equation that shows only those elements/compounds/ions that are directly involved in the chemical reaction

• Must be balanced

What is the equation for phosphate?

PO₄

Write the balanced equation, spectator ions, net ionic equation for: Tin(II) Chloride with Potassium Phosphate

• Balanced equation: 3SnCl_2(aq) + 2K₃PO_4(aq) → Sn₃(PO₄)_2(s) + 6KCl_(aq)

• Spectator ions: Cl^- and K⁺

• Net ionic equation: 3Sn²⁺_(aq) + 2PO₄^3-_(aq) → Sn₃(PO₄)_2(s)

• Do criss-cross method for both sides of the equation, then balance. Split compound. Eliminate spectator ions

• *Must write the charges! Product side will have nothing. Reactant side must balance. Here 3 X 2+ = 6 and 2 X 3- = -6 so they cancel out

Write the balanced equation, spectator ions, net ionic equation for: Nickel(II) Chloride with Sodium Carbonate

• Balanced equation: NiCl_2(aq) + Na₂CO_3(aq) → NiCO_3(s) + 2NaCl_(aq)

• Spectator ions: Cl^- and Na⁺

• Net ionic equation: Ni²⁺_(aq) + CO₃^2-_(aq) → NiCO_3(s)

• Balance using criss cross method (*on the product side, the 2’s cancel out)

• Eliminate spectators

• *Must write the charges! Product side will have nothing. Reactant side must balance.