Q: Calculate the energy of a photon with a wavelength of $500 \ \mathrm{nm}$. ($h = 6.626 \times 10^{-34} \ \mathrm{J} \cdot \mathrm{s}$, $c = 3.00 \times 10^8 \ \mathrm{m}/\mathrm{s}$)

$E = 3.98 \times 10^{-19} \ \mathrm{J}$

Q: Which of the following is the correct formula for calculating the enthalpy change ($\Delta H$) of a reaction using standard enthalpies of formation?

$\Delta H = \sum \Delta H_f^{\circ} (\text{products}) - \sum \Delta H_f^{\circ} (\text{reactants})$

Q: Which of the following is the correct expression for the energy of an electron in the hydrogen atom according to the Bohr model?

$E_n = -2.18 \times 10^{-18} \left( \dfrac{1}{n^2} \right) \ \mathrm{J}$

Question 1

A sample of an ideal gas is held at constant temperature. If the pressure is doubled, what happens to the volume of the gas according to Boyle's Law?

Accepted Answer

The volume is halved.

Question 2

Which equation correctly relates the change in internal energy ($\Delta U$) to heat ($q$) and work ($w$) for a closed system?

Accepted Answer

$\Delta U = q + w$

Question 3

A 50.0 g sample of water is heated from 25.0 $^\circ$C to 75.0 $^\circ$C. Given the specific heat capacity of water is $4.18 \ \mathrm{J} / \mathrm{g} \cdot ^\circ\mathrm{C}$, what is the amount of heat absorbed?

Accepted Answer

$q = 10,450 \ \mathrm{J}$

Question 4

Which of the following best describes the meaning of the quantum number $n$ in atomic structure?

Accepted Answer

It determines the principal energy level of an electron.

Question 5

Calculate the energy of a photon with a wavelength of $500 \ \mathrm{nm}$. ($h = 6.626 	imes 10^{-34} \ \mathrm{J} \cdot \mathrm{s}$, $c = 3.00 	imes 10^8 \ \mathrm{m}/\mathrm{s}$)

Accepted Answer

$E = 3.98 	imes 10^{-19} \ \mathrm{J}$

Question 6

Which of the following elements has the highest first ionization energy?

Accepted Answer

Neon (Ne)

Question 7

A reaction has $\Delta H = -125 \ \mathrm{kJ}$ and $\Delta S = +50 \ \mathrm{J}/\mathrm{K}$. At what temperature (in K) does the reaction become non-spontaneous? ($\Delta G = \Delta H - T \Delta S$)

Accepted Answer

$T > 2500 \ \mathrm{K}$

Question 8

Which of the following is the correct expression for the root mean square speed ($u_{rms}$) of a gas molecule?

Accepted Answer

$u_{rms} = \sqrt{\dfrac{3RT}{M}}$

Question 9

Which statement best explains why atomic radius decreases across a period from left to right?

Accepted Answer

Increasing nuclear charge pulls electrons closer to the nucleus.

Question 10

A balloon contains 2.00 mol of helium gas at 1.00 atm and 273 K. What is the volume of the balloon? ($R = 0.0821 \ \mathrm{L} \cdot \mathrm{atm} / \mathrm{mol} \cdot \mathrm{K}$)

Accepted Answer

$V = 44.8 \ \mathrm{L}$

Question 11

Which of the following best describes the process of entropy ($S$) change in the melting of ice at 0 $^\circ$C?

Accepted Answer

Entropy increases because the molecules become more disordered.

Question 12

Which equation is used to calculate the energy change when a substance is heated but does not change phase?

Accepted Answer

$q = m c_p \Delta T$

Question 13

A student mixes 100.0 g of water at 80.0 $^\circ$C with 100.0 g of water at 20.0 $^\circ$C in an insulated container. What is the final temperature? (Assume no heat loss, $c = 4.18 \ \mathrm{J}/\mathrm{g} \cdot ^\circ\mathrm{C}$)

Accepted Answer

$T_{final} = 50.0 \ ^\circ\mathrm{C}$

Question 14

Which of the following is the correct formula for calculating the enthalpy change ($\Delta H$) of a reaction using standard enthalpies of formation?

Accepted Answer

$\Delta H = \sum \Delta H_f^{\circ} (	ext{products}) - \sum \Delta H_f^{\circ} (	ext{reactants})$

Question 15

Which of the following best explains why noble gases are chemically inert?

Accepted Answer

They have completely filled valence electron shells.

Question 16

A 0.50 mol sample of nitrogen gas ($N_2$) is at 300 K and 2.00 atm. What is its volume? ($R = 0.0821 \ \mathrm{L} \cdot \mathrm{atm} / \mathrm{mol} \cdot \mathrm{K}$)

Accepted Answer

$V = 6.16 \ \mathrm{L}$

Question 17

Which of the following is the correct expression for the energy of an electron in the hydrogen atom according to the Bohr model?

Accepted Answer

$E_n = -2.18 	imes 10^{-18} \left( \dfrac{1}{n^2} ight) \ \mathrm{J}$

Question 18

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 19

Which constant is used to relate the number of particles to moles in chemistry?

Accepted Answer

Avogadro's number, $N_A = 6.022 	imes 10^{23}$

General Chemistry Final Exam Reference Sheet: Equations, Constants, and Periodic Table

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