Q: A solution is prepared by dissolving 5.0 g of NaCl (molar mass = 58.44 g/mol) in enough water to make 250 mL of solution. What is the molarity of the solution?

$M = \frac{5.0\ \text{g}}{58.44\ \text{g/mol}} \div 0.250\ \text{L} = 0.342\ \text{M}$

Q: Which of the following reactions is a redox reaction?

$\text{Mg} + 2\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2$

Q: If the $[\text{H}^+]$ in a solution is $1.0 \times 10^{-5}$ M, what is the pH?

$\text{pH} = -\log(1.0 \times 10^{-5}) = 5$

Q: Calculate the energy of a photon of light with a wavelength of 589 nm. ($h = 6.626 \times 10^{-34}\ \text{J} \cdot \text{s}$, $c = 3.0 \times 10^8\ \text{m/s}$)

$E = \frac{hc}{\lambda} = \frac{6.626 \times 10^{-34} \times 3.0 \times 10^8}{589 \times 10^{-9}} = 3.38 \times 10^{-19}\ \text{J}$

Q: A gas sample has a volume of 25.0 L at 19°C and 1.5 atm. How many moles of gas are present? ($R = 0.0821\ \text{L} \cdot \text{atm} / \text{mol} \cdot \text{K}$)

$n = \frac{PV}{RT} = \frac{1.5 \times 25.0}{0.0821 \times (19 + 273)} = 1.56\ \text{mol}$

Question 1

Which of the following statements best describes molarity?

Accepted Answer

Molarity is the number of moles of solute in one liter of solution.

Question 2

A solution is prepared by dissolving 5.0 g of NaCl (molar mass = 58.44 g/mol) in enough water to make 250 mL of solution. What is the molarity of the solution?

Accepted Answer

$M = \frac{5.0\ 	ext{g}}{58.44\ 	ext{g/mol}} \div 0.250\ 	ext{L} = 0.342\ 	ext{M}$

Question 3

Which of the following is a correct statement about strong and weak electrolytes?

Accepted Answer

Strong electrolytes dissociate completely in water, while weak electrolytes dissociate only partially.

Question 4

Which of the following reactions is a redox reaction?

Accepted Answer

$	ext{Mg} + 2	ext{HCl} ightarrow 	ext{MgCl}_2 + 	ext{H}_2$

Question 5

If the $[	ext{H}^+]$ in a solution is $1.0 	imes 10^{-5}$ M, what is the pH?

Accepted Answer

$	ext{pH} = -\log(1.0 	imes 10^{-5}) = 5$

Question 6

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

A catalyst lowers the activation energy, increasing the rate of reaction.

Question 7

Calculate the energy of a photon of light with a wavelength of 589 nm. ($h = 6.626 	imes 10^{-34}\ 	ext{J} \cdot 	ext{s}$, $c = 3.0 	imes 10^8\ 	ext{m/s}$)

Accepted Answer

$E = \frac{hc}{\lambda} = \frac{6.626 	imes 10^{-34} 	imes 3.0 	imes 10^8}{589 	imes 10^{-9}} = 3.38 	imes 10^{-19}\ 	ext{J}$

Question 8

Which quantum number determines the shape of an orbital?

Accepted Answer

The azimuthal quantum number $l$

Question 9

A gas sample has a volume of 25.0 L at 19°C and 1.5 atm. How many moles of gas are present? ($R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K}$)

Accepted Answer

$n = \frac{PV}{RT} = \frac{1.5 	imes 25.0}{0.0821 	imes (19 + 273)} = 1.56\ 	ext{mol}$

Question 10

Which of the following best explains why the temperature of a gas increases when it is compressed at constant volume?

Accepted Answer

The average kinetic energy of the gas molecules increases as work is done on the gas.

Question 11

Which of the following is the correct electron configuration for Calcium ($Z=20$)?

Accepted Answer

$1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\ 4s^2$

Question 12

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

Accepted Answer

Atomic radius decreases across a period from left to right.

Question 13

A Styrofoam cup calorimeter contains 28.0 g of water at 19.73°C. A 2.05 g sample of a metal alloy is heated to 98.88°C and then quickly added to the water. The temperature of the water rises to 21.33°C. Assuming that no energy is lost to the calorimeter or the surroundings, what is the specific heat of the alloy? ($c_{	ext{water}} = 4.18\ 	ext{J/g} \cdot 	ext{°C}$)

Accepted Answer

$c_{	ext{alloy}} = \frac{m_{	ext{water}} c_{	ext{water}} \Delta T_{	ext{water}}}{m_{	ext{alloy}} \Delta T_{	ext{alloy}}} = \frac{28.0 	imes 4.18 	imes (21.33 - 19.73)}{2.05 	imes (98.88 - 21.33)} = 0.37\ 	ext{J/g} \cdot 	ext{°C}$

Question 14

Which of the following is the correct balanced equation for the reaction of magnesium with hydrochloric acid?

Accepted Answer

$	ext{Mg} + 2	ext{HCl} ightarrow 	ext{MgCl}_2 + 	ext{H}_2$

Question 15

Which of the following statements about the ideal gas law is correct?

Accepted Answer

The ideal gas law assumes that gas molecules do not attract or repel each other and occupy negligible volume.

Question 16

Which of the following is a correct statement about the relationship between wavelength and frequency of electromagnetic radiation?

Accepted Answer

Wavelength and frequency are inversely proportional: $c = \lambda 
u$

Question 17

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

Accepted Answer

$\Delta H = \sum 	ext{Bond energies of reactants} - \sum 	ext{Bond energies of products}$

General Chemistry I: Final Exam Study Guide – Solutions, Thermodynamics, Quantum Mechanics, Gas Laws, and Molecular Models

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