Q: A 50.0 g sample of water ($$C = 4.18\ \mathrm{J/g\cdot ^\circ C}) is $$heated from 25.0 $$^\circC to 75.0$$ $$^\circC. $$How much heat is absorbed?

$$q = mC\Delta T = 50.0\ \mathrm{g} \times 4.18\ \mathrm{J/g\cdot ^\circ C} \times (75.0 - 25.0)\ ^\circ\mathrm{C} = 10,450\ \mathrm{J}$$

Q: A photon has a wavelength of 400 nm. What is its energy in joules?

$$E = \dfrac{hc}{\lambda} = \dfrac{6.626 \times 10$$^{-34}$$\ \mathrm{J\cdot s} \times 3.00 \times 10^8$\ \mathrm{m/s}}{400 \times 10$$^{-9}$$\ \mathrm{m}} = 4.97 \times 10$$^{-19}$$\ \mathrm{J}$$

Q: Calculate the frequency of a photon of red light with a wavelength of 700 nm.

$$\nu = \dfrac{c}{\lambda} = \dfrac{3.00 \times 10^8$\ \mathrm{m/s}}{700 \times 10$$^{-9}$$\ \mathrm{m}} = 4.29 \times 10$$^{14}$$\ \mathrm{s}^{-1}$$

Question 1

A sample of gas is compressed at constant temperature from 2.0 L to 1.0 L against a constant external pressure of 1.5 atm. What is the work done on the gas?

Accepted Answer

$$w = -P_{ext} \Delta V = -(1.5\ \mathrm{atm})(1.0\ \mathrm{L} - 2.0\ \mathrm{L}) = 1.5\ \mathrm{L\cdot atm}$$

Question 2

Which of the following statements best describes an endothermic reaction?

Accepted Answer

The system absorbs heat from the surroundings, and $$\Delta H is $$positive.

Question 3

Calculate the change in internal energy ($$\Delta E) $$for a system that absorbs 150 J of heat and does 40 J of work on the surroundings.

Accepted Answer

$$\Delta E = q + w = 150\ \mathrm{J} + (-40\ \mathrm{J}) = 110\ \mathrm{J}$$

Question 4

A 50.0 g sample of water ($$C = 4.18\ \mathrm{J/g\cdot ^\circ C}) is $$heated from 25.0 $$^\circC to 75.0$$ $$^\circC. $$How much heat is absorbed?

Accepted Answer

$$q = mC\Delta T = 50.0\ \mathrm{g} 	imes 4.18\ \mathrm{J/g\cdot ^\circ C} 	imes (75.0 - 25.0)\ ^\circ\mathrm{C} = 10,450\ \mathrm{J}$$

Question 5

Which of the following reactions is an example of a combustion reaction?

Accepted Answer

$$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\mathrm{O}_2 \rightarrow 6\mathrm{CO}_2 + 6\mathrm{H}_2\mathrm{O}$$

Question 6

A photon has a wavelength of 400 nm. What is its energy in joules?

Accepted Answer

$$E = \dfrac{hc}{\lambda} = \dfrac{6.626 	imes 10$$^{-34}$$\ \mathrm{J\cdot s} 	imes 3.00 	imes 10^8$\ \mathrm{m/s}}{400 	imes 10$$^{-9}$$\ \mathrm{m}} = 4.97 	imes 10$$^{-19}$$\ \mathrm{J}$$

Question 7

Which of the following statements about the quantum numbers for an electron in a hydrogen atom is correct?

Accepted Answer

The principal quantum number $$n$$ determines the energy level, and the angular momentum quantum number $$l$$ determines the shape of the orbital.

Question 8

Which element has the ground state electron configuration $$[\mathrm{Kr}]5s^24$d^5$?

Accepted Answer

Manganese (Mn)

Question 9

A 2.00 g sample of copper ($$C = 0.385\ \mathrm{J/g\cdot ^\circ C}) is $$heated with 10.0 J of energy. What is the temperature change?

Accepted Answer

$$\Delta T = \dfrac{q}{mC} = \dfrac{10.0\ \mathrm{J}}{2.00\ \mathrm{g} 	imes 0.385\ \mathrm{J/g\cdot ^\circ C}} = 12.99\ ^\circ\mathrm{C}$$

Question 10

Which of the following transitions in the hydrogen atom emits a photon with the highest energy?

Accepted Answer

$$n = 4 \rightarrow n = 1$$

Question 11

Which of the following substances will show the greatest temperature change when absorbing 100.0 J of heat? (Specific heat capacities: $$C_{\mathrm{Cu}} = 0.385\ \mathrm{J/g\cdot ^\circ C}$$, $$C_{\mathrm{Au}} = 0.129\ \mathrm{J/g\cdot ^\circ C}$$, $$C_{\mathrm{Fe}} = 0.449\ \mathrm{J/g\cdot ^\circ C}$$, $$C_{\mathrm{Ca}} = 0.647\ \mathrm{J/g\cdot ^\circ C}$$; all samples are 10.0 g)

Accepted Answer

10.0 g Au, $$C = 0.129\ \mathrm{J/g\cdot ^\circ C}$$

Question 12

Which of the following is NOT a standard state?

Accepted Answer

For a liquid, it is 2.5 M

Question 13

Which of the following colors of visible light has the longest wavelength?

Accepted Answer

Red

Question 14

Calculate the frequency of a photon of red light with a wavelength of 700 nm.

Accepted Answer

$$
u = \dfrac{c}{\lambda} = \dfrac{3.00 	imes 10^8$\ \mathrm{m/s}}{700 	imes 10$$^{-9}$$\ \mathrm{m}} = 4.29 	imes 10$$^{14}$$\ \mathrm{s}^{-1}$$

Question 15

Which of the following sets of quantum numbers is valid for a 3p electron?

Accepted Answer

$$n = 3,\ l = 1,\ m_l = 0,\ m_s = +\frac{1}{2}$$

Question 16

How many unpaired electrons are present in the ground state of a nitrogen atom?

Accepted Answer

3

Question 17

Which of the following best explains why atomic emission spectra are unique for each element?

Accepted Answer

Each element has a unique set of allowed energy levels, so the transitions between them produce unique spectral lines.

Question 18

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

Accepted Answer

Neon (Ne)

General Chemistry Study Guide: Thermochemistry, Quantum Mechanics, and Periodic Properties

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