Solutions & Solubility – Interactive Study Tool

Key Terms & Definitions

The language of solutions

Click each term to see its definition, example, and particulate view.

Remember: The solute dissolves INTO the solvent. Water is the "universal solvent" — it dissolves more substances than any other liquid. A solution is always a homogeneous mixture — you can't see the individual components.

Factors Affecting Rate of Dissolving

What makes things dissolve faster?

Click a factor to see the animation and explanation.

Concentration (Molarity)

C = n/V · mol/L

C = n/V

Adjust moles and volume — see concentration update live with a visual of the solution.

Moles (n)1.0 mol

Volume (V)1.0 L

Concentration—

Type—

Calculator: find n, C, or V

n = ×

C = n/V where C is in mol/L (or M), n in mol, V in litres. If you have mass, use n = m/mm first to find moles. Concentrated ≈ > 1 mol/L, dilute ≈ < 0.1 mol/L (approximate — depends on substance).

Dilution & Mixing Solutions

C₁V₁ = C₂V₂ · dilutions only (not reactions!)

C₁V₁ = C₂V₂

The moles of solute stay constant — only the volume changes. Watch the colour fade as you add water.

Initial (stock) solution

C₁ (mol/L)2.0

V₁ (mL)50

Water added (mL)

V_water50

n solute—

V₂ total—

C₂ final—

Mixing two solutions (same solute)

C = (C₁V₁ + C₂V₂) / (V₁ + V₂)

C₁:mol/L

V₁:mL

C₂:mol/L

V₂:mL

Key rule: C₁V₁ = C₂V₂ is for dilutions ONLY — you are adding water (or solvent), not reacting. Moles of solute are conserved. For mixing two solutions of the same solute, use C = n_total / V_total.

Factors Affecting Solubility

How MUCH will dissolve — a different question from how FAST

Rate of dissolving (previous tab) is about speed. Solubility is the maximum amount that can dissolve at a given temperature. Only three things change solubility itself.

1 · Temperature

Most solids are more soluble in hot water (KNO₃ jumps from 13 to 246 g/100 mL between 0 °C and 100 °C). A few solids barely change (NaCl) and a rare few decrease (Ce₂(SO₄)₃). Every gas is LESS soluble in warm water — which is why rivers lose dissolved O₂ in summer and warm soda goes flat.

2 · Pressure (gases only)

Henry's Law: the solubility of a gas is directly proportional to the pressure of that gas above the liquid. Double the CO₂ pressure over a drink and twice as much dissolves. Pressure has essentially no effect on solids or liquids.

3 · Nature of solute & solvent — "like dissolves like"

Polar solvents (water) dissolve polar and ionic solutes (salt, sugar). Non-polar solvents (hexane, oil) dissolve non-polar solutes (fats, iodine). Polar and non-polar do not mix — oil and water form layers. This is why grease needs soap or a non-polar solvent, not water, to shift it.

Solubility Curves

Solubility (g/100mL water) vs temperature

Hover over a substance to highlight its curve. Drag the temperature slider to read solubility values. On or above a curve = saturated (any extra solute stays as solid); below = unsaturated.

Temperature 25°C

Temperature25°C

Selected substanceKNO₃

Solubility at T—

Trend—

On the curve = saturated (the maximum that will dissolve at that temperature) · Above the curve = still saturated — the extra solute simply stays undissolved at the bottom. A solution only becomes supersaturated if it is prepared hot, then cooled slowly and left undisturbed; the slightest disturbance drops it back to saturated. Below the curve = unsaturated (can dissolve more). Most solids become more soluble with heat; gases become LESS soluble with heat (carbonated drinks go flat when warm).

The seed-crystal test

Drop one small crystal of solute into each solution and watch what it does — the classic way to tell the three saturation states apart.

Unsaturated — the crystal dissolves (there is still room for more solute). Saturated — the crystal stays the same size (dissolving and crystallising are balanced). Supersaturated — the crystal triggers sudden crystallisation through the whole beaker, and the solution drops back to saturated plus solid.

Dissociation & Ion Concentration

What happens when ionic compounds dissolve

Select a compound — see its dissociation equation and calculate ion concentrations.

Compound [C]1.0 mol/L

Dissociation is a physical change — the ionic solid separates into its component ions in water. An electrolyte conducts electricity because of these free-moving ions. Mole ratios tell you the concentration of each ion directly from the compound's concentration.

Particulate view — NaCl dissolving

Water is polar: the O end carries a partial negative charge (δ−), the H ends a partial positive charge (δ+). Those charges pull ions off the crystal lattice one at a time and surround each one — a hydration shell.

δ− oxygen atoms turn to face each Na⁺; δ+ hydrogen atoms turn to face each Cl⁻. That ion–dipole attraction is what makes an ionic solid dissolve — and why the freed, mobile ions can carry a current (an electrolyte).

Precipitation Reactions

Molecular · ionic · net ionic equations

Mix two solutions and see if a precipitate forms. Click a reaction to see all three equation types.

Molecular equation: full formulas · Ionic equation: all aqueous species as ions · Net ionic equation: remove spectator ions — only the ions that actually form the precipitate remain. Use solubility rules to identify which product is the precipitate (s).

Solution Stoichiometry

Use C and V to get moles, then cross the mole ratio

A solution reaction is an ordinary stoichiometry problem where the "amount you have" is given as a concentration and a volume. The route is always: C × V → moles → mole ratio → moles → answer (mass, volume of another solution, or a concentration).

n = C × V · then use the balanced equation's mole ratio

Practice — reveal each solution

Periodic Table

Class-standard table · based on mass of carbon-12 = 12.00

Read molar masses off this table when converting between grams and moles in concentration and stoichiometry problems.

Ion Chart

Class-standard chart · common cations, anions & polyatomic ions with their charges

Names, formulae, and charges of common ions — positive ions (cations) and negative ions (anions)

Use these charges to predict which ions a compound dissociates into and to work out precipitation reactions from the solubility rules.

Real-World Applications

Solutions and solubility in everyday life

Solubility

Ocean & dissolved oxygen

Cold ocean water holds more dissolved O₂ than warm water (gas solubility decreases with temperature). Polar oceans support more marine life. Ocean warming from climate change reduces dissolved O₂ — threatening fish populations. Classic gas solubility and temperature relationship.

Pressure & gases

Carbonated drinks

CO₂ is dissolved in drinks under high pressure — increasing gas solubility. When you open the can, pressure drops → CO₂ solubility drops → bubbles form and escape. Warming the drink also lowers CO₂ solubility. That's why warm soda goes flat faster.

Supersaturation

Rock candy & recrystallization

Sugar dissolves more in hot water than cold. Dissolve maximum sugar at high temperature, then cool slowly — the solution becomes supersaturated and sugar crystallizes onto a seed crystal. This is recrystallization — used in both candy making and purifying lab chemicals.

Concentration

IV saline solution

Hospital IV bags contain 0.9% NaCl (w/v) — exactly matching blood's salt concentration (isotonic). Too concentrated (hypertonic) → water leaves cells by osmosis → cells shrink. Too dilute (hypotonic) → water enters cells → cells burst. The concentration must be precise!

Precipitation

Hard water & scale buildup

Hard water contains dissolved Ca²⁺ and Mg²⁺ ions. When heated, they react with carbonate ions to form insoluble precipitates (limescale): Ca²⁺ + CO₃²⁻ → CaCO₃(s). This coats kettle elements, pipes, and shower heads — direct application of precipitation reactions.

Dilution

Windshield washer fluid

Concentrated methanol (C₁ ~100%) is diluted with water to make windshield washer fluid. Using C₁V₁ = C₂V₂ — if you want 4L of 30% methanol, you need 1.2L of pure methanol topped up with 2.8L of water. Industrial dilution — the same equation you use in class, at factory scale.

Solutions & Solubility Practice Quiz

30 questions · 20 seconds each · Speed bonus scoring

🧪

Ready to test your knowledge?

Covers all topics from the course slides — definitions, calculations, solubility curves, precipitation

30

Questions

20s

Per question

1000

Max points

Summary

Quick reference — solutions & solubility

Concept	Formula / Rule	Key point
Concentration	C = n/V (mol/L)	n = m/mm first if given mass
Dilution	C₁V₁ = C₂V₂	Moles conserved; volume increases
Mixing	C = (C₁V₁+C₂V₂)/(V₁+V₂)	Not dilution — adding same solute
Dissociation	NaCl → Na⁺ + Cl⁻	Mole ratio gives ion concentrations
Solubility	g/100mL at given T	Most solids↑ with T; gases↓ with T
Saturation	Seed crystal test	Dissolves=unsaturated; crystallizes=supersaturated
Precipitation	Use solubility rules	Low solubility product = precipitate (s)
Net ionic eq.	Remove spectator ions	Only reacting ions remain

Rate of dissolving factors: smaller particle size · stirring · higher temperature · less solute already dissolved
Solubility factors: nature of solute/solvent · temperature · pressure (gases only)
Types of solutions: 9 possible combinations of solid, liquid, gas solute + solid, liquid, gas solvent

Solutions & Solubility — Interactive Study Tool