CHE 022 Solution

Percent by Mass

is a concentration measure defined as the ratio of the mass of a component (solute) to the total mass of the mixture (solution), multiplied by 100.

Percent by Mass formula

mass of solute/total mass of solution x 100

Mass/Volume Percent

Is a unit of concentration measuring the volume of solute divided by the total volume of the solution, multiplied by 100. It is commonly used for liquid-liquid solutions, such as alcohol in water, expressed as

Mass/Volume Percent Formula

volume of solute/volume of solution x 100

Proof

It is a measure of the content of ethanol (alcohol) in an alcoholic beverage.

Proof formula

Volume of solute/volume of solution % x 2

Parts per million/parts per billion

It is best used to describe the quality of performance or concentration of a substance in a larger mixture. This could be used to describe contents in water, a supplier's defective rate, etc.

Parts per million formula

mass of A in solution/total mass of solution x 10^6 (same for volume)

Parts per billion formula

mass of A in solution/total mass of solution x 10^9 (same for volume)

Mole Fraction

Is the ratio of the number of moles of one component (nA) to the total number of moles in the solution (nA + nB)

Mole fraction formula

XA + nA/nA + nB

Molarity

Is the most common way of expressing the concentration of a solution. It is defined as the number of moles of solute per liter of solution.

Molality

________________ of a solution is the number of moles of solute dissolved per kilogram of solvent.

Dilution

It is the process of reducing the concentration of a solute in a solution by adding more solvent (such as water), without adding more solute. It increases the total volume while lowering the concentration, often calculated using the formula

Dilution formula

M1V1 = M2V2

1. Write the balanced equation (Hint: if ions are involved, writing the net ionic equation will be very helpful!)

2. Start with the given volume

3. Use molarity (mol solute/L solution) to convert volume→moles

4. MOLE RATIO

5. Convert from moles to the desired units using molarity or molar mas

Steps for Stoichiometry

Colligative Properties

Changes in _________________ depend only on the number of solute particles present, not on the identity of the solute particles.

-Vapor pressure lowering

-Boiling point elevation

-Melting point depression

-Osmotic pressure

Common colligative properties

Vapor pressure

Because of solute-solvent intermolecular attraction, higher concentrations of nonvolatile solutes make it harder for solvent to escape to the vapor phase.

Vapor pressure formula

XsolventPsolvent

Boiling point elevation

The change in boiling point is proportional to the molality of the solution. Kb is the molal boiling point elevation constant, a property of the solvent.

Boiling point elevation formula

Kb(m)

Freezing point depression

The change in freezing point can be found similarly. Kf is the molal freezing point depression constant of the solvent.

Freezing point depression formula

Kf(m)

Osmosis

There is net movement of solvent from the area of higher solvent concentration (lower solute concentration) to the are of lower solvent concentration (higher solute concentration).

Osmotic pressure

The pressure required to stop osmosis, if it's the same on both sides of a membrane (i.e., the concentrations are the same), the solutions are isotonic.

Hypertonic

If the solute concentration outside the cell is greater than that inside the cell, the solution is _________

Water will flow out of the cell, and crenation results.

Hypotonic

If the solute concentration outside the cell is less than that inside the cell, the solution is __________. Water will flow into the cell, and hemolysis results.

Osmotic pressure formula

(n/V)RT = MRT