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UCLA Chemistry 20L
Final Exam
27
Chemistry
Undergraduate 2
12/06/2010

Additional Chemistry Flashcards

 


 

Cards

Term

 

 

 

Simple Distillation

Definition

 

Separating liquids boiling BELOW 150°C

 

Difference in boiling point should be at least 25°C

 

We used this to separate ethyl acetate from toluene

Term

 

 

Vacuum Distillation

Definition

 

 

Separating liquid mixture ABOVE 150°C at 1 atm

Term

 

 

 

Fractional Distillation

Definition

 

 

 

Difference in boiling point is less that 25°C

Term

 

 

 

Steam Distillation

Definition

 

 

 

Used mainly to isolate tars and oil mixtures

Term

 

 

 

Normal Boiling Point

Definition

 

 

 

Temperature at which the vapor pressure of the liquid is exactly equal to 1 atm

Term

 

 

 

Dalton's Law of Partial Pressures

Definition

 

 

The total pressure of the system equals the sum of the partial vapor pressure of each component

 

Phexane + Ptoluene = 760 torr

Term

 

 

 

Raoult's Law

Definition

 

 

The partial vapor pressure of a component in the solution is equal to the PURE vapor pressure of A times its mole fraction

 

PA = P0A * XA

 

 

Term

 

 

Relationship between vapor pressure and boiling point

Definition

 

 

High vapor pressure normally means low boiling point

 

Low vapor pressure normally means high boiling point

Term

 

 

 

Retention Time

Definition

 

 

The time between injection of the liquid mixture and the output of the GC signals from the GC detector

Term

 

 

 

Mobile Phase

Definition

 

 

 

The carrying gas in gas chromatography. Most common carrying gas is Helium.

Term

 

 

 

Stationary Phase

Definition

 

 

The gas chromatography column. The inside of the column usually consists of a HIGH BOILING POINT liquid coated on a solid support. The entire column is then sealed inside a coiled metal tube.

Term

 

 

London Dispersion Forces

Definition

 

- Weakest intermolecular force

 

- Not a permanent dipole

 

- It is not always true that low boiling point implies London forces

 

Term

 

 

 

Dipole Forces

Definition

 

Example: Electronegativity

 

C = O

  δ+      δ -

Term

 

 

 

Hydrogen Bonding

Definition

 

H - O

 

H - N

 

H - F

Term

 

 

 

Ionic Forces

Definition

 

 

 

NaCl

Term

 

 

 

Goals of Gas Chromatography

Definition

 

 

Separation

Quantification (%)

Identification (retention time)

Term

 

 

 

Speed of the GC recorder

Definition

 

 

 

4.0 cm/min

Term

 

 

 

Area of individual signal on GC chromatogram

Definition

 

 

 

Width at half height x height (unit in cm2)

Term

 

 

 

% Composition for each individual component in GC

 

Definition

 

 

 

 

100% x (Individual Area / Total Area)

Term

 

 

 

The 5% Rule (acid-base)

Definition

 

 

Y/(0.1000) x 100% ≤ 5%

Term

 

 

 

At half equivalence point . . .

Definition

 

[HA] = [A-]

 

moles of weak acid = moles of conjugate base

 

pH = pKa

Term

 

 

 

At equivalence point . . .

Definition

 

 

[HA] = [OH-]

 

moles of weak acid = moles of strong base

Term

 

 

Composition of Buffer Solutions

Definition

 

Weak acid and its conjugate base

 

OR

 

Weak base with its conjugate acid

Term

 

 

Limits of the Henderson-Hasselbalch Equation

Definition

 

 

- Ka for the weak acid must be within the limits oft he approximation (≤10-5)

- Applies only to buffer solutions

Term

 

 

Range of Visible Light

Definition

 

 

 

380 nm - 750 nm

Term

 

 

 

Beer's Law

Definition

 

 

 

A = εbc

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