Chapter 6 - IM Forces and Lab Techniques Flashcards Preview

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Flashcards in Chapter 6 - IM Forces and Lab Techniques Deck (16)
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1
Q

Describe the relationship between strong intermolecular forces and boiling point, melting point, and vapor pressure

A

If a compound has strong IM forces = increased BP, increase MP, and decreased VP

2
Q

If two compounds have the same weight, describe the relationship between branching, boiling point, and melting point.

A

more branching = decreased BP

more branching = increased MP

3
Q

Purpose of the following lab technique - extraction

Describe the layers in the separation funnel.

Is the solvent that is added last non polar or polar? organic or aqueous?

A

Separate polar substances from non polar

The top layer is the non polar, organic layer - while the bottom is the aqueous polar layer.

The solvent is non polar, organic

4
Q

in what type of scenario will the organic solvent be in the aqueous layer, instead of on top of the organic layer?

A

if the solvent is chlorinated; this is because it is dense in water

5
Q

Describe how to extract COOH in an acid base extraction

A

extract COOH using aqueous NaOH or NaHCO3, separate, then add acid to the water layer to precipitate COOH and decrease the pH of water

6
Q

Describe how to extract phenol in an acid base extraction

A

Extract phone by using aq NaOH, separate, then add HCl to precipitate and decrease pH of water

7
Q

Describe how to extract an amine in acid base extraction

A

Add HCl first to protonate and make amine water soluble, then neutralize with base to precipitate amine

8
Q

What is the purpose of simple and fractional distillation?

A

separate two or more volatile liquids; simple is for compounds that have BP’s that differ by about 25 degrees and fractional is to separate compounds with similar BP’s

9
Q

What is the purpose of sublimation?

A

purification of volatile solids

heat the solid and collect on accompanying test tube

10
Q

What is the purpose of recrystallization

A

purification of a solid

heat solid in hot solvent and collect solid as the solvent cools

11
Q

Gas liquid chromatography will determine the relative _____ of each compound in a ____ mix by observing the ___ ___

A

abundance, liquid, boiling point

12
Q

Thin layer chromatography will separate ____ ____ substances by _____

Because the plate is (polar/nonpolar) and the solvent is (polar/nonpolar), the most soluble substances will travel ____ and the least soluble substances will travel the ______.

A

non volatile, solubility/polarity

plate = polar

solvent = non polar

most soluble = travels least

least soluble = travels fastest/furthest distance

13
Q

Polar substances will have a ____ Rf value, while a non polar will have a ____ Rf value

A

smaller, larger

14
Q

Describe the purpose of column chromatography

What type of compound will dissolve the best in the eluent?

A

separate compounds by polarity

polar compounds - remember like dissolves like

15
Q

Which of the following is sometimes used to purify volatile solids?

A. Thin-layer chromatography
B. Gas-liquid chromatography
C. Sublimation
D. Distillation
E. Fractional distillation

A

C

16
Q
  1. Which of the following is sometimes used to purify non-volatile solids?

A. Thin-layer chromatography
B. Gas-liquid chromatography
C. Sublimation
D. Distillation
E. Recrystallization

A

E