Q: Find the corresponding energy of a photon for each of the following frequencies: (a) $$2.2$$ GHz (b) $$4.2$$ THz (c) $$102.5$$ MHz (Use $$E = h\nu$$ with $$h = 6.626 \times 10$$^{-34}$$ J·s.)

a. $$1.5 \times 10$$^{-24}$$ J; b. 2.8$$ \times $$10^{-21} J$$; c. $$6.79 \times 10$$^{-26}$$ J

Question 1

Calculate the temperature at which $$SO_2$$ molecules will have the same mean speed as $$NO_2$$ molecules at $$63.0^	ext{o}C. ($$Use $$u_{rms} = \sqrt{\frac{3RT}{M}}.) $$Report your answer in degrees Celsius.

Accepted Answer

204°C

Question 2

At $$298	ext{K}$$, the reaction $$2	ext{PCl}_3(g) + O_2$(g) ightarrow 2	ext{POCl}_3(g)$$ ($$K_c = 16) $$occurs in the atmosphere. With $$2.4$$ mol $$PCl_3$$ and $$3.1$$ mol $$O_2$$ and an initial total pressure of $$1.38$$ atm, a gas mixture is created. What is the container's volume? (Use the ideal gas law: $$PV = nRT.)$$

Accepted Answer

97 L

Question 3

A $$25.0-L $$reaction vessel containing a mixture of $$CO_2$$ and excess $$F_2 is $$set up at $$125^	ext{o}C$$ and $$3.50$$ atm of pressure. According to the equation $$CO_2(g) + 4F_2(g$$) \rightarrow $$CF_4(g) + 2OF_2(g$$)$$, a spark ignites CO_2$, resulting in its complete combustion. The temperature returns to 125^	$$ext{o}C$$ after the reaction, and the pressure of the mixture of product gases (CF_4$, OF_2$, and unreacted F_2$) is found to be 2.85$ atm. What are the partial pressures of the individual gases in the product mixture?

Accepted Answer

$$P_{F_2$} = 1.44$$ atm, $$P_{OF_2$} = 0.498$$ atm, $$P_{CF_4$} = 0.249$$ atm

Question 4

Which conditions increase the likelihood of a gas deviating from ideal behavior?
I. low pressure or high temperature
II. polar molecules
III. nonpolar molecules
IV. high pressure or low temperature

Accepted Answer

II and IV

Question 5

The complete combustion of a hydrocarbon produced $$17.2 g of$$ $$CO_2$$ and $$2.45 g of$$ $$H_2O. $$The heat given off was $$463 kJ. $$Determine the mass of the substance combusted.

Accepted Answer

4.97 g

Question 6

Given the following reaction and standard enthalpy values, find $$\Delta H_f^\circ (kJ/$$mol) for cyclohexane ($$C_6H_{12}$$):
$$C_6H_{12}(l) + 9O_2(g) \rightarrow 6CO_2(g) + 6H_2O(l)$$, $$\Delta H_{rxn} = -3919.6 kJ$$
$$\Delta H_f^\circ(CO_2$) = -393.5 kJ/$$mol
$$\Delta H_f^\circ(H_2O) = -285.8 kJ/$$mol

Accepted Answer

-3240.3 kJ/mol

Question 7

Do materials with high heat content always have a high temperature? Does a system always reduce its internal heat content if it performs work? How do kinetic energy and potential energy differ?

Accepted Answer

No; No; Kinetic energy is due to the motion of an object while potential energy is due to the position/place of an object.

Question 8

Which of the following will have $$\Delta H$$ greater than $$\Delta U$$?
I. $$2Hg(g) + O_2$(g) \rightarrow 2H_2O(g)
II$$. $$MgSO_3(s) + 2HI(aq$$) \rightarrow $$MgI_2(aq) + H_2O(l$$) + $$SO_2(g$$)$$
III. CO(g) + H_2O(g$$) \rightarrow $$CO_2(g$$) + $$H_2(g$$)$$
IV. H_2SO_4(aq) + $$LiS(aq) \rightarrow H_2S(g) + Li_2SO_4(aq)$$

Accepted Answer

I and III

Question 9

Determine the enthalpy of the reaction using Hess's law:
$$Ag_2O(s) + 2HCl(aq) \rightarrow 2AgCl(s) + H_2$(g) + O_2$(g)$$
Given the following data:
$$2Ag(s) + 1/2O_2(g) \rightarrow Ag_2O(s)$$ $$\Delta H = -31.1 kJ/$$mol
$$Ag(s) + 1/2Cl_2(g) \rightarrow AgCl(s)$$ $$\Delta H = -127.0 kJ/$$mol
$$H_2O(l) + Cl_2$(g) \rightarrow 2HCl(aq) + 1/2O_2(g)$$ $$\Delta H = -48.6 kJ/$$mol
$$H_2(g$$) + $$O_2(g$$) \rightarrow H_2O(l)$$ $$\Delta H = -285.8$$ kJ/mol

Accepted Answer

111.5 kJ/mol

Question 10

Consider the two substances M and N. Substance M has a mass of $$5.16 g $$and is initially at $$18.6^	ext{o}C. $$Substance N has a mass of $$22.3 g $$and is initially at $$56.4^	ext{o}C. $$The two substances come into contact with each other and reach thermal equilibrium. The final temperature of both substances is $$49.7^	ext{o}C. $$Given that the specific heat capacity of substance N is $$2.34 J/g$$·°C, calculate the specific heat capacity of substance M. (Use $$q = mc\Delta T.)$$

Accepted Answer

1.12 J/g·°C

Question 11

Calculate the uncertainty in the velocity for a neutron if the uncertainty in its position is $$605 pm. ($$Use Heisenberg's uncertainty principle: $$\Delta x \cdot m_n \Delta v \geq \frac{h}{4\pi}$$, $$m_n = 1.675 	imes 10$$^{-27}$$ kg, h = 6.626$$ 	imes $$10^{-34} J$$·s.)

Accepted Answer

$$\Delta v \geq 75.5 m/s$$

Question 12

Find the corresponding energy of a photon for each of the following frequencies:
(a) $$2.2$$ GHz
(b) $$4.2$$ THz
(c) $$102.5$$ MHz
(Use $$E = h
u$$ with $$h = 6.626 	imes 10$$^{-34}$$ J·s.)

Accepted Answer

a. $$1.5 	imes 10$$^{-24}$$ J; b. 2.8$$ 	imes $$10^{-21} J$$; c. $$6.79 	imes 10$$^{-26}$$ J

Question 13

Arrange the given orbitals in order of decreasing energy: $$5f$$, $$3s$$, $$6d$$, $$4s$$, $$7p.$$

Accepted Answer

7p \u003e 6d \u003e 5f \u003e 4s \u003e 3s

Question 14

Identify the false statement and correct it.
A. Ultraviolet light has a smaller wavelength than microwaves.
B. The glow from burning wood, black lights, and radio frequencies, are all forms of electromagnetic radiation.
C. The wavelength of radiation decreases as the frequency increases.
D. The speed of electromagnetic radiation in a vacuum increases as the frequency of the light increases.

Accepted Answer

(D) The speed of electromagnetic radiation in a vacuum is constant.

Question 15

For each of the following elements, provide the complete electron configuration.
(a) Rb
(b) S
(c) Ar
(d) As

Accepted Answer

a) $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$ $$3d^{10}$$ $$4p^6$$ $$5s^1$$; b) $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^4$$; c) $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$; d) $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$ $$3d^{10}$$ $$4p^3$$

Question 16

Consider the following orbitals: (i) 1s, (ii) 4d, (iii) 4f, (iv) 6g. Identify the maximum number of electrons that can be contained in each.

Accepted Answer

(i) 2, (ii) 10, (iii) 14, (iv) 18

Question 17

The following statements summarize the experiments about quantum mechanics. Identify the incorrect statement.
A. The Electron Diffraction is about the wave-like behavior of electrons. This was observed when electrons go through a grating and produce an interference pattern.
B. The Heisenberg's Uncertainty Principle is about the measurements of the variables of an electron. This states that the position and velocity of an electron are never known.
C. The Photoelectric Effect is about the emission of electrons due to the absorption of electromagnetic radiation. This occurs when light hits a piece of metal and electrons are ejected.
D. The Atomic emission spectra is about the discrete energy levels of electrons. This states that energy levels in an atom are quantized. Thus, electrons are found on distinct energy levels.

Accepted Answer

B

General Chemistry Exam Study Guide: Gases, Thermodynamics, Quantum Mechanics, and Atomic Structure

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