Solutions and Mixtures Aqueous Solutions pg. 292 Something is dissolved in water…the something can vary. When compounds dissolve in water, it means that.

Solutions and Mixtures

Aqueous Solutions pg. 292

•Something is dissolved in water…the something can vary.

•When compounds dissolve in water, it means that they break apart into the ions that make them up. The only covalent compounds that do this are acids. Ionic compounds dissolve in water easily.

•Example of ionic equation

What are solutions?

Solutions are homogeneous mixtures containing two or more substances called the solute and the solvent.

Solute: dissolves (less)Solvent: dissolving medium (more)

Solutions Vocabulary

Soluble: able to be dissolved in a solvent

Insoluble: unable to be dissolved in a solvent

Immiscible: two liquids that cannot dissolve or mix (oil and water)

Miscible: two liquids that are soluble in each other

SolvationWhen a solution forms, solute particles

separate from one another and the solute and solvent particles must mix. The solvent particles completely surround the surface of the solute, pull them apart, and surround the solute particles.

Solvation: process of solvent particles surrounding the solute particles forming a solution.

“Like dissolves like.”

To determine whether a solvent and solute are alike, you must examine the bonding and the polarity of the particles and the intermolecular forces between particles.

These properties affect solvation, the process of forming a solution.

Factors Affecting Rate of Solvation

Solute and solvent particles coming in contact with each other is KEY in forming a solution. Increasing the contact will increase the formation of the solution.

3 ways to increase contact or collisions:1. Agitating the mixture2. Increasing the surface area of the solute3. Increasing the temperature of the

solvent

Solubility

Maximum amount of solute that will dissolve in a solvent at a particular temperature and pressureSaturated: contains max. amount at that

T&PUnsaturated: contains less than max.

amount at that T&PSupersaturated: contains more than max.

amount at that T&P HUH?

Temperature and Pressure

HIGH temperature: at very high temperatures, more solid solute can dissolve in a liquid solvent. [supersaturated solutions start this way]

HIGH pressure: at high pressures, more gaseous solute can dissolve in a liquid solvent. [soft drinks are made this way]

Solubility Chart

Concentration of Solutions

The concentration of a solution is a measure of how much solute is dissolved in a specific amount of solvent or solution.

Molarity: most common units of solution concentration; # of moles solute dissolved in one liter of the solution

Molarity Calculations

Molarity: moles of solute liter of solution

If given grams, remember to change it to moles.

Stop

Practical Stuff: Making a Solution

If given a stronger solution, you can dilute it (water it down) to make the weaker solution that you want.

Diluting Solutions

Beaker #1 contains concentrated salt water, 2M NaCl. I want to dilute it. What do I do?

Add more water…in other words, add more solvent.

TO DILUTE A SOLUTION, ADD MORE SOLVENT.

Diluting Solutions

Does adding solvent affect the amount of solute in the solution?

NO

Diluting Solutions

If you already have a solution molarity, but you want a different molarity:

USE THIS EQUATION: M1V1 = M2V2

Sample Calculation

I have 500.0mL of a 2M NaCl solution, but I want a 1M NaCl solution. How much watershould I add?

Sample Calculations

I want 0.50L of a 0.300M CaCl2

solution, but I have a 2.00M CaCl2 solution. How much of the 2.00M CaCl2 solution is needed?

Practice

Notes: Practice Problems.

Molality

Another unit for concentrationm=moles of solute per kilogram

of solvent

Colligative Properties

Physical properties of solutions that change depending on the number of solute particles in solutionVapor pressure loweringBoiling point elevationFreezing point depression*

Reactions that form Precipitates pg. 292-293 When solutions of sodium hydroxide and

copper(II) chloride are mixed, a precipitate forms…copper(II) hydroxide.

What does solutions of sodium hydroxide and copper(II) chloride mean?

So the ionic compounds fall apart…and the copper and hydroxide ions come together to form the solid copper(II) hydroxide.

The sodium and chloride ions remain dissolved.

Ionic Equations pg. 293

Ionic equations show all the particles in a solution dissolved as ions.

Complete ionic equations show all ions and precipitates.

Net ionic equations show only how the precipitate came to form…all spectator ions are removed.

Example