Chem 108: Exam 2

DTb = iKbm

lower vapor pressure means need higher temp to boil dTb=increase in boiling point, i=van't Hoff factor, Kb=proportionality constant, m=molality

Unit of measurement for osmolarity

osmol/L OR moles of individual dissolved species/L

Polarity of C-O bonds and O-H bonds

C-O bonds are NOT as polar as O-H bonds

Benzene Molal Points

C6H6 Freezing Point: 5.5C Kf: 4.9 C/m Boiling Point: 80.1C Kb: 2.53 C/m

Carbon Tetrachloride Molal Points

CCl4 Freezing Point: -22.3C Kf: 29.8 C/m Boiling Point: 76.8C Kb: 5.02 C/m

Ethanol Molal Points

CH3CH2OH Freezing Point: -114.6C Kf: 1.99 C/m Boiling Point: 78.4C Kb: 1.22 C/m

Magnitude of charge with van't Hoff Factor

More Charge means more IMF. So it is less likely to be overcome by water

More energy is needed to reach the boiling point for a solution compared to pure solvent

More energy is required to overcome IMF

Osmosis

Movement of solvent across a semi-permeable membrane

Will 2 sides of a U beaker ever reach equilibrium of solution

No because there is more gravity on the higher concentration solution. This is due to increased osmotic pressure

Collisions of elastic molecules

No loss of energy when collided. There are no attractive forces or space taken up

Stabile Substances

Non volatile substances. Not readily vaporized, high IMFs. More easily dissolved

Significant Figures 0's rule

Non-zero digits are always significant. Any zeros between two significant digits are significant. A final zero or trailing zeros in the decimal portion ONLY are significant (If no decimals, following zeros are not significant)

Gas Law

PV=nRT

After holding your breath for a long time and you inhale

Pressure increases greatly, and so will also increase the number of moles

If temperature is raised, what happens to the pressure in the system?

Pressure is increased because of direct relationship

If volume is increased, what will happen to the pressure in the system?

Pressure will decreased because indirectly related

Colligative Properties

Properties of solutions that depend ONLY on the NUMBER of solute particles present. Does NOT focus not the identity of solute particles

Kb, molal boiling point

Property of EACH solvent.

In the middle of the afternoon, is water over the water or the land less dense?

The air over the land

Which body of air will rise at the beach?

The air over the land because it's less dense than the air over the water

Significant Figures while Adding/Subtracting

The answer will have the same number of SMALLEST sig fig number (from the last order of operation)

Significant Figures while Multiplying/Dividing

The answer will have the same number of SMALLEST sig fig number (from the last order of operation)

Molecular Speed and Temperature

The colder the molecule, the less speed it has

What can we say about density of the gas in the shark ballon

The density of the gas inside the shark is lighter than the density of gas in the room

DTf = iKfm

solute particles interferes with formation of lattice arrangement of solvent molecules dTf=freezing point depression, i=van't Hoff factor, Kf=proportionality constant, m=molality

When using the osmotic pressure law: R Value

.0821 L/atm

van't Hoff Factor for molecular compounds

1

Liter/Grams Ratio

1 Liter/1000 grams

Atmosphere (atm)

1 atm

Pascal (pa)

1 atm= 1.01325 x 10^5 PA

Kilopascal (kPa)

1 atm= 101.325 kPa

Millimeter of mercury (mmHg)

1 atm= 760 mmHg

Bar

1 atm=1.01325 bar

Milibar (mbar)

1 atm=1013.25 mbar

Pounds per square inch (psi)

1 atm=14.7 psi

Inches of mercury

1 atm=29.92 inches of Hg

Torr

1 atm=760 torr

How to determine the van't Hoff factor of a solute?

1) check if it is an ion or molecular compound 2) Check its formula (ion parts)

Boiling Point Elevation

A colligative property. Solvent is most important, temperature-dependent, so temperature-independent concentration units are used.

Melting Point Depression

A colligative property. Solvent is most important, temperature-dependent, so temperature-independent concentration units are used.

Vapor Pressure Depression

A colligative property. Solvent is most important, temperature-dependent, so temperature-independent concentration units are used.

Osmotic Pressure

A colligative property. Molarity is used, but T appears in formula

How to make a non polar molecule more soluble?

Add an Acid or a Base

How to find the liters of solution when given grams and density of the solution

Add up the Grams of solution and set ration of 1ml/grams (density) and multiply it by 10^3 to go from mL to Liters

DTb or DTf

Added to the normal boiling or freezing point of the solution

Alcohol Functional Group Solubility

Alcohols can have H bonds, making them very polar

Pressure formula

Amount of force applied to an area: P=F/A

Similarities of Gas laws

Molarity formula is used to derive it

Ideal gas

At STP, 1 mol of ideal gas/22.414 L

What factors are affected if you heat a steel container?

Average kinetic energy per gas particle. Collision Frequency. Pressure

How to check to see if a solute is soluble

Consider the solvent, is that polar or non polar. Then look at the solute, what intra/intermolecular bonds does it have?

When using the osmotic pressure law: Temperature

Convert it to Kelvins

To determine what is the solvent/solute when given the grams of substances

DO NOT COMPARE WITH THE GIVEN GRAMS. Convert the grams to moles With the molecular weight

When inhaling air

Diaphragm contracts and is pushed down. Pressure decreases, volume increases

When exhaling air

Diaphragm relaxes and is pushed up. Pressure increases, volume decreases

Pressure units of a barometer

Difference in heights

Strong Electrolyte

Dissociates "Completely" to form ions in solution.

Osmosis regarding solutes

From lower concentration of solutes to a higher concentration of solutes

Which direction will air flow if you are standing at the shore

From water to land because pressure moves from higher to lower

Differences of Gas Laws

Gas law is "Gas" Based. And osmotic pressure is solution based

Kinetic-Molecular Theory

Gases consist of large molecules of molecules that are in a continuous, random motion.

Each mole of solutes (Electrolytes)

Gives more than 1 mol of dissolved particles

Water Molal points

H2O Freezing Point: 0.0C Kf: 1.86 C/m Boiling Point: 100C Kb: .52 C/m

Hypertonic Solution

Higher concentration of dissolved solutes. Example: Corn Syrup or Salt Water

Osmosis regarding solvents

Higher concentration of solvents to a lower concentration of solvents

Molarity Formula

Molarity= moles of solute/liters of solution

What affects the density of a gas?

Molecule's nucleus size. Even if you have the same number of molecules, what matters is it's weight

Pressure of a gas is measured by

Molecules colliding with the side of the container

In a closed system, relationship of volume and pressure

Increase in volume will lead to a decrease in pressure

Formula of a compound

Indicates the expected number of particles into solution

Solubility of polar head with long, non polar body (Like stearic acid)

Is not soluble in water or octane because of the polar/non polar ratio. it forms a Miscelles

As you go higher in elevation, what happens to the pressure?

It decreases. Molecules of gas are farther apart

In order for a solute to change the boiling point of a solvent

It has to dissolve

If you're at the bottom of a pool, what happens to the pressure

It increases because gravity/pressure is increased

What happens to a pendulum in an accelerating car

It will move towards the back of the car because it is more dense than the air

What happens to a helium ballon in an accelerating car

It will move towards the front of the car because it is less dense than air

Hypotonic Solution

Lower concentration of dissolved solutes. Example: Water

When solving a molality/molarity/ solution ratio

Make sure to Label all aspects of the equation with actual problem's units (to minimize confusion)

Osmolarity

Measure of solute concentration

Barometer

Measures atmospheric pressure in the air

Molality Formula

Molality= moles of solute/kg of solvent

Volatility of a Substance

Related to the substance's vapor pressure.

Isotonic solution

Same concentration of solutes and solvent in solution

How to find Mole Fraction of a solution

Set up ratios with labels, multiply by the molecular weight to get grams- moles. Last ratio: Solute (moles)/ Solute+ Solvent (moles)

The freezing point of water is lowered proportional to the number of solute species present

So the substance with a higher van'T Hoff factor will contribute more particles- the more the freezing and boiling points.

How would you confirm the results of the egg test were not a fluke?

Switch the eggs from their baths and TEST AGAIN!!

Why are some ionic compounds more soluble than others

Take into effect Coulomb's law. If an ion is more stable together, the less likely water will break those strong dipole-dipole interactions

van't Hoff Factor for electrolytes

Takes into account the dissociation of a strong electrolyte to credit the effect of the solution

What does the barometer depend on?

Temperature, location, weather.

What do you predict will happen when an egg is placed in hypotonic solution?

The Water will enter the egg/cell and the egg will INCREASE in mass

What do you predict will happen when an egg is placed in hypertonic solution?

The Water will leave the egg/cell and the egg will DECREASE in mass

When a solute is added

The freezing point is lowered and the boiling point is raised

The lower the vapor pressure

The less readily the substance will vaporize. The lower the volatility, t he substance can be readily found as a liquid or solid

The higher the vapor pressure of a substance

The more readily the substance will vaporize. The higher volatility, the substance can readily found as a gas

If you close your mouth and nose while you breathe in

The pressure in the lungs when you try to inhale will be less than atmospheric pressure

Actual driving force that makes breathing occur

Vacuum force because the pressure and volume gradient changes

Atmospheric Pressure

Weight of the air per unit of area

A dissolved solute in a solution which contains very polar bonds will have a bigger Impact on the change in boiling point than a less polar compound

Yes, it feeds back into the van't Hoff factor. The more polar a substance is, the more it will separate

Saline

You can't give a patient straight water into their veins, because the red blood cells will burst. You need the salt to balance out the water

Why could handling PCP without gloves be dangerous for your brain

Your fingers are hydrophilic and PCP is Non polar. The 2 substances could interact and sink into your blood stream.

When doing van't Hoff problems

Your guess is a POSSIBILITY. You really need a solubility chart and experimental values to be sure

pi=iMRT

sucking pressure generated by solutions in which water is drawn into a solution, amount of pressure that must be applied to counteract the attraction of water molecules for the solution pi=osmotic pressure, i=van't Hoff factor, M=molarity, R=ideal gas, T=temp water moves to higher solute concentration

Osmotic Pressure Gas Law

π=iMRT