Bonding and thermodynamics

Ionic =

metal (left side) + nonmetal (right side) - opposite sides of periodic table

If you see NH₃ or H₂O

its probs a coordinate covalent bond

Which of the following molecules CANNOT participate in hydrogen bonding with water?

a hydrogen bond has to be bonded to N, O, or F

what are these examples of:

• NH₃ + H⁺ → NH₄⁺

• BF₃·NH₃

• [Fe(H₂O)₆]³⁺

• [Cu(NH₃)₄]²⁺

coordinate covalent bonds

covalent bond =

nonmetal + nonmetal

Double or triple bonds count as

one electron group

one lone pair =

1 group

what is the hybridization of this BF₃

sp² because Boron is electron deficient and has no lone pairs

work through how to do this:

What is the hybridation of the central atom in PCl₃?

-draw it out (lone pairs = 1. single, double, triple = 1)

2- sp, 3- sp², 4- sp³

Answer: sp³

ALWAYS electron-deficient = no lone pairs = sp

beryllium (Be)

Which of the following correctly describes the molecular shape of CS₂?

linear

how do you determine what goes in the middle of the lewis structure

CS₂

the one with the lowest electronegativity

so C

list the hybridzation rules

sp - 2 electron groups, linear

sp²- 3 electron groups, trigonal plannar

sp³ - 4 electron groups, tetrahedral

Which of the following bonds is the most polar?

the bigger the difference in electronegativity the in a covalent bond, the more polar it is

3 bonds + 0 lone pairs =

Ex. BF₃

trigonal planar (120)

2 bonds + 1 lone pair =

Ex. SO₂

bent (120)

4 bonds + 0 lone pairs =

Ex. CH₄

tetrahedral (109.5)

3 bonds + 1 lone pair

Ex. NH₃, PCl₃

Trigonal pyramidal (107)

what is one of the most polar bonds you will see

Si - O

when is something most likely polar

when bonded to oxygen

what are these molecules

• CO₂

• CH₄

• O₂

• N₂

• CCl₄

nonpolar (symmetric) - london dispersion

what are these molecules

• H₂O

• NH₃

• SO₂

• HCl

• CH₃OH

polar (assymetric) - dipole dipole

how would i solve this: London dispersion forces are the primary intermolecular forces in which of the following molecules?

first look what hydrogen bonds: H bonded go N, O, or F

then see if its polar (assymetric)- dipole dipole

then nonpolar (symmetric) - london dispersion forces

how would I do this

Given the following data:

NO₂(g)                        ΔH_f° = +33.2 kJ/mol

N₂O₄(g)                       ΔH_f° = +11.1 kJ/mol

Which statement is true for the reaction below?

2 NO₂(g) → N₂O₄(g)

product - reactants

11.1 - 2(33.3)

DO NOT FORGET THE 2 OUT IN FRONT

Is SO₂ polar or nonpolar

polar

which one is more nonpolar SO₂ or BCl₃

BCl₃ because it has no oxygen, oxygen makes something more polar

what increases entropy (ΔS)

solid → liquid → gas

increase in moles

breaking bonds

does this reaction show an increase or decrease in entropy?

2 C₃H₈O(l) + 9 O₂(g) → 6 CO₂(g) + 8 H₂O(l)

decrease in entropy because the moles of gas goes from 9 to 6

How would you do this:

The decomposition of sodium azide, 2 NaN₃(s) → 2 Na(s) + 3 N₂(g), has the following reaction coordinate diagram:

products is lower then reactants: H = negative

solid → gas: S = + (increase in entropy = +)

how do I do this

What is the ΔH° for the conversion of one mole of C₂H₆O(l) to C₂H₄O(l)?

2 (C₂H₄O) make -2334, so you have to divide it by 2 and then subtract (reactant - product; top - bottom)

answer: -200