lab final flashcards

What are colligative properties?

Properties of solution that depend on number of dissolved solute particles

four colligative properties

Vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure

vapor pressure and nonvolatile solute added

Vapor pressure decreases

adding solute and boiling point

Boiling point increases

freezing point and solute added

Freezing point decreases

osmotic pressure and increased solute concentration

Osmotic pressure increases

solute [] increase and freezing point

Freezing point decreases

more solute

Boiling point increases.

vapor pressure and [] of solute increase

Vapor pressure decreases

higher boiling point, a 10% or 5% NaCl solution

10% NaCl solution

lower freezing point, 5% NaCl or 2% NaCl

5% NaCl solution

more solute and vapor pressure

Lower vapor pressure

vapor pressure

pressure exerted by vapor in equilibrium with its liquid

boiling point

The temperature at which the vapor pressure of a liquid equals atmospheric pressure.

boiling point when pressure decreases

Boiling point decreases

osmosis

solvent through semipermeable membrane from a less [] solution to more [] solution

semipermeable membrane

membrane allows certain particles or molecules to pass through

osmotic pressure

The pressure required to stop osmosis.

relationship between molarity and temperature at constant osmotic pressure

inversely proportional

hypotonic solution

solution with a lower solute concentration than the solution it is compared with

putting cell into hypotonic solution

Water enters the cell and the cell swells

hypertonic solution

solution with a higher [] compared to outside solution

cell in hypertonic solution

Water leaves the cell and the cell shrinks.

isotonic solution

A solution with approx same solute [] as the cell, no net movement of water.

reaction rate

The change in concentration of a reactant or product per unit time.

rate law

Rate = k[A]^m[B]^n.

k in a rate law

The rate constant.

m and n in rate law

reaction orders for A and B

determine overall reaction order

Add individual reaction orders

determination of exponents in a rate law

No. They must be determined experimentally.

zero order reactant when [] doubles

The rate stays the same

Why does a zero order reactant disappear from the simplified rate law?

any concentration raised to the zero power equals 1, so the reactant does not affect the reaction rate.

first order reactant when [] doubles

The rate doubles.

rate when concentration doubles in second order

rate increases by a factor of 4

third order reactant when concentration doubles?

The rate increases by a factor of 8

If [A] doubles and rate doubles, what is the order in A?

First order.

order if [A] doubles and rate quadruples

Second order

If [A] doubles and rate increases eightfold, what is the order in A?

Third order.

If [A] doubles but rate does not change, what is the order in A?

Zero order.

If a reaction is second order in NO and first order in O2, what is its overall reaction order?

Third order.

chemical equilibrium

When the forward and reverse reaction rates are equal and reactant and product concentrations remain constant.

dynamic equilibrium

forward and reverse reactions continue at equal rates

free energy value at equilibrium

lowest possible value

numerator of an equilibrium expression

Products

denominator of an equilibrium expression

Reactants

exponents in an equilibrium expression

coefficients from the balanced chemical equation

matter forms excluded in equilibrium expression

pure liquid and solid

Shift when K>1

Products

Shift when K<1

Reactants

difference between Q and K

Q is the current condition; K is equilibrium condition

shift when Q < K

Right toward products

shift when Q > K

Left toward reactants

when Q = K

The system is at equilibrium.

Le Châtelier's principle

system shifts in the direction that reduces the effect of the disturbance

reactant added to equilibrium system

The system shifts right toward products.

remove reactants

equilibrium shifts left

product added

The system shifts left toward reactants.

product is removed

The system shifts right toward products.

equilibrium shift when pressure increases

The side with fewer moles of gas.

Decreasing pressure shifts equilibrium toward which side?

The side with more moles of gas.

Decreasing volume has the same effect as doing what to pressure?

Increasing pressure.

heat placement in endothermic reaction

The reactant side

heat placement in exothermic reaction

The product side.

Increasing temperature in an endothermic reaction

Right toward products.

Decreasing temperature in an endothermic reaction

Left toward reactants

Increasing temperature in an exothermic reaction

Left toward reactants.

Decreasing temperature in an exothermic reaction

Right toward products.

acid

donates H+ ions or protons

base

accepts H+ ions or protons

acidity

amount of dissolved H+ ions in solution

neutralization

reaction between acid and base

pH equation

pH = −log[H⁺]

acidic

pH below 7

neutral

pH 7

What pH values are basic?

pH above 7

difference of one pH unit

10% difference in H+ concentration

difference of -2 pH units

100 times more acidic

Ka

The acid ionization constant.

large Ka

A stronger acid.

lower pKa

weaker acid

Kb

The base ionization constant.

strong acid and water

Completely ionizes.

weak acid in water

Partially ionizes

What is the general Kb expression for B + H2O ⇌ BH+ + OH

Kb = [BH⁺][OH⁻] / [B]

pH titration curve

change in pH as titrant is added

equivalence point

The point where enough titrant has been added to completely react with the analyte.

equivalence point on a titration curve

vertical change in pH

half equivalence point

pH=pKa, half of the weak acid has converted to conjugate base

calculate pKa from Ka

pKa = −log(Ka)

Ka from pKa

Ka = 10^-pka

hard water

high levels of dissolved minerals or metal ions

ions involved with water hardness

Mg2+ and Ca2+

soft water

0ppm

moderately hard water

61ppm

hard water

121 ppm

very hard water

180ppm<

What type of agent is EDTA

A chelating agent.

What does a chelating agent do?

Binds metal ions.

What indicator is used in the hard water EDTA titration?

EBT

hard water EBT titration with EDTA color shift

Pale purple to blue