CH. 10 — Molarity

What is a ratio unit?

A unit that has 1 kind of base unit on top (numerator) and another kind of bae unit on bottom (denominator)

• Ex: distance/time or mass/volume

What is a single unit?

1 kind of base unit, no denominator

• Ex: grams per 100 milliliters is asking for grams

  • WANTED: ? single unit =

What is a solution?

It is composed of 2 parts: solute & solvent

What is a solute?

Part of the solution being dissolved (doesn’t need to be a solid)

• Ex: Sugar can be dissolved in water to form a sugar-water solution

  • Sugar is the solute

What is a solvent?

The medium that the solute is disolved

• Ex: Sugar can be dissolved in water to form a sugar-water solution

  • Water is the solvent

What is a homogeneous mixture?

If the solute completely dissolves in the solution (usually the case)

What is a concentrated solution?

If the solution contains a relatively large amount of solute

What is a dilute?

If the solution contains a relatively small amount of solute

What is molarity?

Term for concentration that relates to the number of moles of solute in a liter of solution

How is molarity abbreviated?

M

How is a compound or ion indicated of molarity?

Using square brackets around the compound/ion

• Ex: [Na+] means “molarity of sodium ion“

What is the formula of molarity?

Molarity (M) = moles of solute/Liters of solution

Solute

Solid or liquid

Solvent

Any liquid

If solvent = water, what is it?

An aqueous solution

$$\frac{mol}{L}=molL^{-1}=molar$$

What is the formula of molarity?

12 in

1 ft

3 ft

1 yd

5280 ft

1 mi

1 in

2.54 cm

0.6214 mi

1 km

$$6.022\cdot10^{23}$$

What is Avogadro’s number?

1 L

1000 mL

If “# unit X • Y^-x” is DATA, write in DATA:

# Unit X = 1 Unit Y^x

If “unit X • Y^−x” is WANTED, write WANTED:

?$\frac{UnitX}{UnitY^{X}}=$

Examples of glassware used to measure solution volumes

Pipettes, burets, volumetric flasks

Aqueous solution

Water that contains one or more dissolved substances

Molar concentration

Moles of solute per 1 L of solution

What forms can moles solute per 1 liter of solution come in?

• Concentration or brackets [] or

• A capital M or molar or molarity

• mol/L or mol • L^-1

If “0.50 M X” is in a problem, write…

DATA: 0.50 mol X = 1 L X soln.

If “0.50 mol • L^-1 X” is DATA, write…

DATA: 0.50 mol X = 1 L X soln.

See “[X] = 0.50 mol/L”? Write…

DATA: 0.50 mol X = 1 L X soln.