Question 1

Using Hess's Law and the following reactions, calculate $$\Delta H$$ for the reaction:

$$2\ \mathrm{C}(s) + 2\ \mathrm{H}_2\mathrm{O}(g) \rightarrow \mathrm{CH}_4(g) + \mathrm{CO}_2(g)$$

Given:

$$\mathrm{CO}(g) + \mathrm{H}_2(g) \rightarrow \mathrm{C}(s) + \mathrm{H}_2\mathrm{O}(g)\ \ \Delta H = -131\ \mathrm{kJ}$$

$$\mathrm{CO}(g) + \mathrm{H}_2\mathrm{O}(g) \rightarrow \mathrm{CO}_2(g) + \mathrm{H}_2(g)\ \ \Delta H = -41\ \mathrm{kJ}$$

$$\mathrm{CO}(g) + 3\ \mathrm{H}_2(g) \rightarrow \mathrm{CH}_4(g) + \mathrm{H}_2\mathrm{O}(g)\ \ \Delta H = -206\ \mathrm{kJ}$$

Accepted Answer

$$-116\ \mathrm{kJ}$$

Question 2

Given the following standard enthalpies of formation, calculate $$\Delta H$$ for the reaction:

$$3\ \mathrm{Fe}_2\mathrm{O}_3(s) + \mathrm{CO}(g) \rightarrow 2\ \mathrm{Fe}_3\mathrm{O}_4(s) + \mathrm{CO}_2(g)$$

Heats of Formation:

$$\mathrm{Fe}_2\mathrm{O}_3(s) = -824.2\ \mathrm{kJ/mol}$$

$$\mathrm{Fe}_3\mathrm{O}_4(s) = -1118.4\ \mathrm{kJ/mol}$$

$$\mathrm{CO}(g) = -110.5\ \mathrm{kJ/mol}$$

$$\mathrm{CO}_2(g) = -393.5\ \mathrm{kJ/mol}$$

Accepted Answer

$$-47.2\ \mathrm{kJ}$$

Question 3

The combustion of ethane is represented by:

$$2\ \mathrm{C}_2\mathrm{H}_6(g) + 7\ \mathrm{O}_2(g) \rightarrow 4\ \mathrm{CO}_2(g) + 6\ \mathrm{H}_2\mathrm{O}(l)\ \ \Delta H = -3120\ \mathrm{kJ}$$

How much energy is released when $$30.00\ \mathrm{g} of $$ethane is combusted? (Molar mass $$\mathrm{C}_2\mathrm{H}_6 = 30.08\ \mathrm{g/mol})$$

Accepted Answer

$$-777.9\ \mathrm{kJ}$$

Question 4

Arrange the following regions of the electromagnetic spectrum in order of increasing energy: infrared, microwave, ultraviolet, visible.

Accepted Answer

Microwave $$\u003c$$ Infrared $$\u003c$$ Visible $$\u003c$$ Ultraviolet

Question 5

Photons with relatively low energy correspond to light with:

Accepted Answer

long wavelength and low frequency.

Question 6

What is the wavelength (in nm) of light that has a frequency of $$3.62 	imes 10$$^{14}$$\ \mathrm{Hz}$$? (Speed of light $$c = 3.00 	imes 10^8$\ \mathrm{m/s})$$

Accepted Answer

$$829\ \mathrm{nm}$$

Question 7

Light is quantized into packets of energy called:

Accepted Answer

photons.

Question 8

In a hydrogen atom, what is the wavelength of light emitted when an electron falls from $$n=4 to$$ $$n=2$$?

Accepted Answer

$$486.2\ \mathrm{nm}$$

Question 9

When the principal quantum number $$n is $$small, what does this indicate about the electron's position and energy?

Accepted Answer

It is closer to the nucleus and lower in energy.

Question 10

What are the possible values of $$m_l$$ when $$l = 4$$?

Accepted Answer

$$-4, -3, -2, -1, 0, +1, +2, +3, +4$$

Question 11

Which of the following is a valid set of quantum numbers for a p-type orbital in the third principal energy level?

Accepted Answer

$$n = 3,\ l = 1,\ m_l = +1$$

Question 12

Which of the following best describes the photoelectric effect?

Accepted Answer

The emission of electrons from the surface of a metal when light shines on the metal.

Question 13

Which scientist's model of the atom had electrons traveling in fixed orbits around the nucleus?

Accepted Answer

Niels Bohr

Question 14

For a wave, the distance from the center line to a peak is called:

Accepted Answer

Amplitude

Question 15

The Pauli Exclusion Principle states:

Accepted Answer

No two electrons in an atom can have the same set of four quantum numbers.

Question 16

When writing the shorthand electron configuration for chlorine, which noble gas symbol is used?

Accepted Answer

Ne

Question 17

Which scientist proposed that if waves could have particle-like properties, then particles could have wavelike properties?

Accepted Answer

Louis de Broglie

Question 18

Which type of visible light has the highest frequency?

Accepted Answer

Blue

Question 19

Interference between waves that causes them to cancel each other out is known as:

Accepted Answer

destructive interference.

Question 20

Which type of orbital is represented by the quantum number $$l = 0$$?

Accepted Answer

s

General Chemistry Practice Test #4 – Step-by-Step Study Guidance

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