Q: A 100 g sample of water is heated from 25°C to 75°C. If the specific heat of water is $$4.18 \ \mathrm{J/g \cdot ^\circ C}$$, how much energy is required for this process?

$$Q = 100 \times 4.18 \times (75-25) = 20,900 \ \mathrm{J}$$

Q: Which of the following equations is used to calculate the energy of a transition between two energy levels in the hydrogen atom?

$$E = -2.18 \times 10$$^{-18}$$ \left( \frac{1}{n_f^2$} - \frac{1}{n_i^2$} \right) \ \mathrm{J}$$

Q: If the speed of light is $$c = 3.00 \times 10^8$ \ \mathrm{m/s}$$ and a photon has a wavelength of $$600 \ \mathrm{nm}$$, what is its frequency?

$$5.00 \times 10$$^{14}$$ \ \mathrm{Hz}$$

Question 1

Which of the following best describes the First Law of Thermodynamics?

Accepted Answer

The total energy of the universe is constant; energy can be transferred or transformed but not created or destroyed.

Question 2

A 100 g sample of water is heated from 25°C to 75°C. If the specific heat of water is $$4.18 \ \mathrm{J/g \cdot ^\circ C}$$, how much energy is required for this process?

Accepted Answer

$$Q = 100 	imes 4.18 	imes (75-25) = 20,900 \ \mathrm{J}$$

Question 3

Which equation correctly relates the energy of a photon to its frequency?

Accepted Answer

$$E = h 
u$$

Question 4

A chemical reaction is carried out in a bomb calorimeter at constant volume. Which of the following statements is true?

Accepted Answer

The heat measured equals the change in internal energy ($$\Delta U) of $$the reaction.

Question 5

Which of the following best describes the relationship between wavelength ($$\lambda) $$and frequency ($$
u) of $$electromagnetic radiation?

Accepted Answer

They are inversely proportional: as wavelength increases, frequency decreases.

Question 6

Which of the following equations is used to calculate the energy of a transition between two energy levels in the hydrogen atom?

Accepted Answer

$$E = -2.18 	imes 10$$^{-18}$$ \left( \frac{1}{n_f^2$} - \frac{1}{n_i^2$} ight) \ \mathrm{J}$$

Question 7

Which quantum number determines the shape of an orbital?

Accepted Answer

Angular momentum quantum number ($$l)$$

Question 8

A reaction releases 500 kJ of energy. If the limiting reactant is 2 moles, what is the energy released per mole?

Accepted Answer

$$250 \ \mathrm{kJ/mol}$$

Question 9

Which of the following best explains why metals tend to have high metallic character?

Accepted Answer

They have low ionization energies and low electron affinities.

Question 10

Which of the following statements about the electromagnetic spectrum is correct?

Accepted Answer

Radio waves have lower frequencies than visible light.

Question 11

If the speed of light is $$c = 3.00 	imes 10^8$ \ \mathrm{m/s}$$ and a photon has a wavelength of $$600 \ \mathrm{nm}$$, what is its frequency?

Accepted Answer

$$5.00 	imes 10$$^{14}$$ \ \mathrm{Hz}$$

Question 12

Which of the following is the correct order for filling atomic orbitals according to the Aufbau principle?

Accepted Answer

$$1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p \rightarrow 4s \rightarrow 3d$$

Question 13

Which of the following best describes ionization energy?

Accepted Answer

The energy required to remove an electron from a neutral atom.

Question 14

Which of the following transitions in the hydrogen atom would emit the highest energy photon?

Accepted Answer

$$n=2 to$$ $$n=1$$

Question 15

Which quantum number describes the orientation of an orbital in space?

Accepted Answer

Magnetic quantum number ($$m_l)$$

Question 16

A sample of methane is combusted in a bomb calorimeter. The temperature of the water increases by $$2.5 \ ^\circ \mathrm{C}$$, the mass of water is $$500 \ \mathrm{g}$$, and the specific heat of water is $$4.18 \ \mathrm{J/g \cdot ^\circ C}. $$What is the heat released by the reaction?

Accepted Answer

$$Q = 500 	imes 4.18 	imes 2.5 = 5,225 \ \mathrm{J}$$

Question 17

Which of the following statements about electron affinity is correct?

Accepted Answer

Electron affinity is the energy change when an atom gains an electron.

Question 18

Which of the following best explains why the energy of a photon increases as its wavelength decreases?

Accepted Answer

Because $$E = h 
u$$ and $$
u = c / \lambda$$, so as $$\lambda$$ decreases, $$
u$$ increases and $$E$$ increases.

Question 19

Which of the following is a correct statement about the shapes of atomic orbitals?

Accepted Answer

s orbitals are spherical, p orbitals are dumbbell-shaped, and d orbitals are cloverleaf-shaped.

Thermochemistry, Quantum Mechanics, and Periodic Properties: Study Notes

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