Q: A sample of gas has a volume of 25 L at 19°C and 1.5 atm. How many moles of gas are present in the sample? (R = 0.0821 L·atm/mol·K)

$$n = \dfrac{PV}{RT} = \dfrac{1.5 \times 25}{0.0821 \times 292} \approx 1.56~\text{mol}$$

Q: Calculate the wavelength in nanometers of infrared radiation that has a frequency of $$9.76 \times 10$$^{13}$$ Hz. (c = 3.00$$ \times $$10^8 m/s)$$

$$\lambda = \dfrac{c}{\nu} = \dfrac{3.00 \times 10^8$}{9.76 \times 10$$^{13}$$} = 3.07 \times 10$$^{-6}$$~\text{m} = 3070~\text{nm}$$

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 3.2 g of glucose (C$$_6H$_{12}O$_6$$, molar mass = 180 g/mol) in 250 mL of water. What is the molarity of the solution?

Accepted Answer

$$0.071~	ext{M}$$

Question 3

Which of the following best explains why the auto-ionization of water leads to the formation of H$$^+$$ and OH$$^-$$ ions?

Accepted Answer

Water molecules transfer a proton from one molecule to another, resulting in H$$_3O$^+$$ and OH$$^-. $$The H$$_3O$^+ is $$often represented as H$$^+.$$

Question 4

Which of the following is a correct representation of the ideal gas law?

Accepted Answer

$$PV = nRT$$

Question 5

A sample of gas has a volume of 25 L at 19°C and 1.5 atm. How many moles of gas are present in the sample? (R = 0.0821 L·atm/mol·K)

Accepted Answer

$$n = \dfrac{PV}{RT} = \dfrac{1.5 	imes 25}{0.0821 	imes 292} \approx 1.56~	ext{mol}$$

Question 6

Which of the following is true about strong acids compared to weak acids?

Accepted Answer

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

Question 7

If the [H$$^+$$] in a solution is $$3.0 	imes 10$$^{-6}$$ M, what is the pH?

Accepted Answer

$$pH = -\log[H^+] = 5.52$$

Question 8

Which of the following best describes oxidation in a redox reaction?

Accepted Answer

Oxidation is the loss of electrons from a substance.

Question 9

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 dropped into 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? ($$c_{water} = 4.18~	ext{J/g} \cdot 	ext{°C})$$

Accepted Answer

$$c_{alloy} = \dfrac{m_{water} c_{water} \Delta T_{water}}{m_{alloy} \Delta T_{alloy}} = \dfrac{28.0 	imes 4.18 	imes (21.33-19.73)}{2.05 	imes (98.88-21.33)} \approx 0.36~	ext{J/g} \cdot 	ext{°C}$$

Question 10

Calculate the wavelength in nanometers of infrared radiation that has a frequency of $$9.76 	imes 10$$^{13}$$ Hz. (c = 3.00$$ 	imes $$10^8 m/s)$$

Accepted Answer

$$\lambda = \dfrac{c}{
u} = \dfrac{3.00 	imes 10^8$}{9.76 	imes 10$$^{13}$$} = 3.07 	imes 10$$^{-6}$$~	ext{m} = 3070~	ext{nm}$$

Question 11

Which quantum number determines the shape of an orbital?

Accepted Answer

The azimuthal quantum number $$l$$

Question 12

Which of the following statements about catalysts is correct?

Accepted Answer

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

Question 13

Which of the following is the correct electron configuration for Calcium (atomic number 20)?

Accepted Answer

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

Question 14

Which of the following best describes the relationship between temperature and kinetic energy for an ideal gas?

Accepted Answer

The average kinetic energy of gas molecules is directly proportional to the absolute temperature.

Question 15

Which of the following is a correct statement about the periodic trends in atomic radius?

Accepted Answer

Atomic radius decreases across a period from left to right.

Question 16

Which of the following is the correct formula for calculating the energy of a photon?

Accepted Answer

$$E = h 
u$$

Question 17

Which of the following is a correct statement about the enthalpy change ($$\Delta H) of a $$reaction?

Accepted Answer

A negative $$\Delta H$$ indicates the reaction is exothermic.

Question 18

Which of the following best describes the dual nature of light?

Accepted Answer

Light behaves as both a particle and a wave due to quantum mechanics.

General Chemistry I: Comprehensive Study Notes and Problem Guide

Guida di studio - Domande di pratica

Study guide - Flashcard