ACS Final Review 3 - CHEM 109

Thermochemistry

100

You conduct a reaction in a calorimeter, with a thermometer inserted to gauge the temperature of the solution in which the reaction occurs. The thermometer reading increases from 295K to 301K as the reaction proceeds. What is the sign of the change in enthalpy for the reaction?

Negative

200

How much heat is released in the following reaction with 10.0g Al and excess iron (III) oxide?

Fe₂O₃ + 2Al -> Al₂O₃ + 2Fe        ΔH = -157kJ

29.1kJ heat released (-29.1kJ)

300

Given the following data:

C(graphite) + O₂ -> CO₂         ΔH = -393.5kJ

2CO + O₂ -> 2CO₂                 ΔH = -566.0kJ

What is the ΔH for the following reaction?

2C(graphite) + O₂ -> 2CO

-221.0kJ

400

A 55.0g piece of iron at 425°C (C_Fe = 0.499 J/g*°C) is dropped into 600.0g water (C_H2O = 4.184 J/g*°C) at 25°C. The iron and the water will both reach the same final temperature. What is that final temperature? (Hint: the iron loses as much heat as the water gains)

29°C

EM Spectrum

100

Out of three photons with wavelengths of 413nm, 688nm, and 532nm, which has the highest energy? Which has the highest frequency?

Highest energy: 413nm

Highest frequency: 413nm

200

What is the frequency of a photon with a wavelength of 410nm?

7.3*10¹⁴ Hz

300

How much energy, in joules, is associated with a photon of 410nm?

4.9*10^-19 J

400

What is the energy of one mole of photons that have a wavelength of 410nm?

2.9*10⁵ J/mol photons

Quantum Theory

100

How many electrons can be in the 4d subshell? How many orbitals are in the 4d subshell?

Electrons: 10e^-

Orbitals: 5

200

Which sets of quantum numbers are not allowed? Why?

(2, 1, -1, -1/2)

(3, 0, 0, +1/2)

(2, 1, 2, +1/2)

(4, 4, -2, -1/2)

(4, 2, 1, +1)

(2, 1, 2, +1/2)

(4, 4, -2, -1/2)

(4, 2, 1, +1)

300

What do each of the four quantum numbers, n, l, m_l and m_s represent?

n: size and energy

l: shape

m_l: orbital orientation(s)

m_s: electron spin

400

What are the quantum numbers for the two electrons in the 4s orbital of a titanium atom?

(4, 0, 0, +1/2), (4, 0, 0, -1/2)

IM Forces

100

What are the five intermolecular forces in order of strongest to weakest?

ion-ion

ion-dipole

dipole-dipole

H-bonding (sub-category of dipole-dipole)

London dispersion forces

200

What are examples of each intermolecular force?

ion-ion: NaCl

ion-dipole: H₂O with Na⁺ and Cl^-

dipole-dipole: H₂O molecules

H-bonding: H₂O molecules

London-dispersion: H₂ molecules

300

Which alcohol is most soluble in water?

CH₃CH₂OH (ethanol)

CH₃(CH₂)₄OH (pentanol)

CH₃(CH₂)₇OH (octanol)

CH₃CH₂OH (ethanol)

400

As intermolecular forces increase in strength, what happens to the following parameters? (increase/decrease)

Boiling point

Melting Point

Surface tension

Viscosity

Vapor pressure

Boiling point: increase

Melting Point: increase

Surface tension: increase

Viscosity: increase

Vapor pressure: decrease

Hybridization and VSEPR

100

What is the bond angle between H atoms in methane (CH₄)?

109.5°

200

What is the hybridization of one carbon of acetylene? How many sigma and pi bonds are in the whole molecule?

Hybridization: sp

3 sigma bonds, 2 pi bonds

300

What is the hybridization of xenon in the molecule XeF₄?

Hybridization: sp³d²

400

What is the molecular geometry of PF₅? What is the hybridization of the phosphorus atom in the molecule PF₅?

Molecular geometry: trigonal bipyramidal

Hybridization: sp³d