Q: A balloon filled with helium gas at 20°C occupies 32.0 L. What is the volume of the balloon if it is placed in liquid nitrogen at -196°C, assuming pressure is constant?

$$V_2$$ = $$V_1$$ \times \frac{$$T_2$$}{$$T_1$$} = 32.0 \times \frac{77}{293} = 8.4\ \mathrm{L}$$

Q: A sample of gas occupies 22.4 L at STP and 9.85 L at 100°C and 1.00 atm. How many moles of gas did the sample originally contain?

$$n = \frac{PV}{RT} = \frac{(1.00)(9.85)}{0.0821 \times 373} = 0.32\ \mathrm{mol}$$

Q: Which of the following is the correct formula for calculating the percent yield of a reaction?

$$\%\ yield = \frac{\text{actual}}{\text{theoretical}} \times 100$$

Question 1

Which of the following statements best explains why only certain energies are allowed for the electron in a hydrogen atom according to the Bohr model?

Accepted Answer

Electrons can only occupy orbits where their energy matches the energy difference between quantum levels.

Question 2

A balloon filled with helium gas at 20°C occupies 32.0 L. What is the volume of the balloon if it is placed in liquid nitrogen at -196°C, assuming pressure is constant?

Accepted Answer

$$V_2$$ = $$V_1$$ 	imes \frac{$$T_2$$}{$$T_1$$} = 32.0 	imes \frac{77}{293} = 8.4\ \mathrm{L}$$

Question 3

Which of the following is a FALSE statement about diluted solutions?

Accepted Answer

The number of moles of solvent remains unchanged.

Question 4

Which of the following pairs of compounds are both soluble in water?

Accepted Answer

AgNO$$_3$$ and KNO$$_3$$

Question 5

What is the oxidation number change for the iron atom in the reaction $$2Fe_2O_3 + 3C \rightarrow 4Fe + 3CO_2$$?

Accepted Answer

Decreases from +3 to 0

Question 6

Which of the following assumptions regarding kinetic molecular theory is most frequently cited to explain the compressibility of a gas?

Accepted Answer

The volume of the particles is negligible compared to the volume of the container.

Question 7

A student dissolves three different substances, AX, AY, and A$$_2Z$$, in water. The results show that AY conducts electricity the strongest, while AX$$_2 is $$the weakest. Which is the strongest and weakest electrolyte?

Accepted Answer

Strongest: AY; Weakest: AX$$_2$$

Question 8

What is the final pressure in a 10.0 L flask containing 0.200 mol of H$$_2$$ and 0.215 mol of N$$_2 at 20.0$$°C?

Accepted Answer

$$P = \frac{nRT}{V} = \frac{(0.415)(0.0821)(293)}{10.0} = 1.00\ \mathrm{atm}$$

Question 9

Which of the following best describes what happens to the volume of a gas as it is heated to 350°C while the volume is kept constant?

Accepted Answer

The pressure increases.

Question 10

Which of the following is the correct net ionic equation for the reaction between aqueous lithium sulfate and aqueous barium bromide?

Accepted Answer

$$Ba^{2+}(aq$$) + $$SO_4$$^{2-}(aq) \rightarrow $$BaSO_4(s$$)$$

Question 11

A sample of gas occupies 22.4 L at STP and 9.85 L at 100°C and 1.00 atm. How many moles of gas did the sample originally contain?

Accepted Answer

$$n = \frac{PV}{RT} = \frac{(1.00)(9.85)}{0.0821 	imes 373} = 0.32\ \mathrm{mol}$$

Question 12

Which of the following best describes the energy change when a hydrogen electron makes a transition from n = 4 to n = 2?

Accepted Answer

Energy is emitted.

Question 13

Which of the following is the correct formula for calculating the percent yield of a reaction?

Accepted Answer

$$\%\ yield = \frac{	ext{actual}}{	ext{theoretical}} 	imes 100$$

Question 14

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

Accepted Answer

The average kinetic energy of the gas particles increases, causing more frequent and forceful collisions with the container walls.

Question 15

Which of the following is the correct relationship for the rate of effusion of a gas according to Graham's law?

Accepted Answer

$$	ext{rate} \propto \frac{1}{\sqrt{MM}}$$

Question 16

Which of the following best describes the difference between the two electromagnetic waves shown, where wave (a) has a longer wavelength than wave (b)?

Accepted Answer

Wave (a) has lower energy and lower frequency than wave (b).

Question 17

Which of the following is the correct principal quantum number and angular momentum quantum number for the orbital shown below (d-orbital)?

Accepted Answer

$$n = 4$$ and $$l = 2$$

Question 18

Which of the following is the correct formula for calculating the molarity of a solution?

Accepted Answer

$$M = \frac{n}{V}$$

General Chemistry Exam 2 Study Guide

Guida di studio - Domande di pratica

Study guide - Flashcard