Q: A photon of green light has a frequency of $$6.0 \times 10$$^{14}$$\ \mathrm{s}^{-1}. $$What is its energy in joules?

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

Question 1

A sample of 10 g of sodium bicarbonate ($$\mathrm{$$NaHCO_3$$}) $$reacts completely with excess hydrochloric acid ($$\mathrm{HCl}) at$$ $$1.0$$ atm and $$20\ ^\circ\mathrm{C}. $$How many liters of carbon dioxide ($$\mathrm{CO_2$}) $$gas are produced? (Molar mass of $$\mathrm{$$NaHCO_3$$} = 84\ \mathrm{g/mol}$$, $$R = 0.0821\ \mathrm{L\ atm\ $$mol^{-1}$$\ K$$^{-1}$$})$$

Accepted Answer

$$1.34\ \mathrm{L}$$

Question 2

Which of the following is NOT a postulate of the kinetic molecular theory of gases?

Accepted Answer

Gas particles exert attractive and repulsive forces on each other.

Question 3

A gas expands from $$2.0\ \mathrm{L} to$$ $$6.0\ \mathrm{L}$$ against an external pressure of $$1.2\ \mathrm{atm}. $$Calculate the work done by the gas in joules. ($$1\ \mathrm{L\ atm} = 101.3\ \mathrm{J})$$

Accepted Answer

$$486\ \mathrm{J}$$

Question 4

Which law states that at constant temperature, the volume of a fixed amount of gas is inversely proportional to its pressure, and how does kinetic molecular theory explain this?

Accepted Answer

Boyle's Law; decreasing volume increases collision frequency, raising pressure.

Question 5

If ammonia ($$\mathrm{NH_3$}) $$and hydrogen chloride ($$\mathrm{HCl}) $$are released at opposite ends of a tube, and $$\mathrm{HCl}$$ has diffused $$1.00\ \mathrm{m}$$, how far has $$\mathrm{NH_3$}$$ effused? (Molar masses: $$\mathrm{NH_3$} = 17\ \mathrm{g/mol}$$, $$\mathrm{HCl} = 36.5\ \mathrm{g/mol})$$

Accepted Answer

$$1.47\ \mathrm{m}$$

Question 6

Under which conditions do the ideal gas law assumptions fail, and which equation better describes real gas behavior under these conditions?

Accepted Answer

At high pressure and low temperature; the van der Waals equation.

Question 7

A $$5.4\ \mathrm{g}$$ sample of peanuts is burned under a beaker containing $$466\ \mathrm{g} of $$water. The water temperature rises from $$8.5\ ^\circ\mathrm{C} to$$ $$74.6\ ^\circ\mathrm{C}. $$What is the caloric value per gram of peanuts? ($$1\ \mathrm{food\ calorie} = 1000\ \mathrm{calories}$$, $$c_{\mathrm{water}} = 4.18\ \mathrm{J/g\ ^\circ C})$$

Accepted Answer

$$6.0\ \mathrm{food\ calories/g}$$

Question 8

A photon of green light has a frequency of $$6.0 	imes 10$$^{14}$$\ \mathrm{s}^{-1}. $$What is its energy in joules?

Accepted Answer

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

Question 9

Which color of visible light corresponds to photons with the highest energy per photon?

Accepted Answer

Violet

Question 10

An electron falls from the $$n=6 to $$the $$n=3$$ quantum level in a hydrogen atom. What is the wavelength of the emitted photon? ($$R_H = 1.097 	imes 10^7$\ \mathrm{m}^{-1})$$

Accepted Answer

$$1094\ \mathrm{nm}$$

Question 11

Which set of quantum numbers is NOT allowed for an electron in an atom?

Accepted Answer

$$n=3,\ l=3,\ m_l=0,\ m_s=+1/2$$

Question 12

Which subatomic particle exhibits both wavelike and particle-like properties?

Accepted Answer

Electron

Question 13

Which atom in each pair is larger, and why? a) Ne and Li

Accepted Answer

Li, because it has fewer protons and less effective nuclear charge.

Question 14

Why does atomic radius decrease steadily along the 2nd and 3rd rows of the periodic table?

Accepted Answer

Increasing nuclear charge pulls electrons closer.

Question 15

Which atom has the greater ionization energy: Beryllium (Be) or Boron (B)?

Accepted Answer

Be, because its 2s electrons are more tightly held.

Question 16

Arrange the following ions in order from largest to smallest: $$\mathrm{S$$^{2-}$$}$$, $$\mathrm{Cl^-}$$, $$\mathrm{K^+}$$, $$\mathrm{Ca$$^{2+}$$}.$$

Accepted Answer

$$\mathrm{S$$^{2-}$$} \u003e \mathrm{Cl^-} \u003e \mathrm{K^+} \u003e \mathrm{Ca$$^{2+}$$}$$

Question 17

Which two factors most affect the effective nuclear charge ($$Z_{\mathrm{eff}}) $$experienced by an electron?

Accepted Answer

Number of protons and shielding by inner electrons.

Question 18

Why do the 2s, 2p, 3d, and 4f orbitals have different energies in multi-electron atoms?

Accepted Answer

Electron-electron repulsion and shielding cause energy splitting.

Question 19

Which pattern best describes electron affinity as you move across a period (row) in the periodic table?

Accepted Answer

Electron affinity generally becomes more negative (increases).

Question 20

How do we know that the 2p orbital has three subdivisions ($$m_l = -1, 0, +1$$)?

Accepted Answer

The magnetic quantum number $$m_l$$ can take values from $$-l to$$ $$+l.$$

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