Question 1

A sample of gas is collected in a flask connected to an open-ended mercury manometer, as shown in the first image. The atmospheric pressure is 1.00 atm and the difference in mercury levels (Δh) is 20.0 mm, with the mercury higher on the side open to the atmosphere. What is the pressure of the gas in the flask, in atm? (1 atm = 760 mm Hg)

Accepted Answer

$$0.97$$ atm

Question 2

Which of the following statements about the graph in the second image (Charles' Law) is correct?

Accepted Answer

I only: Data of this type were used to obtain the absolute temperature (Kelvin) scale.

Question 3

Which of the following is NOT an assumption of the kinetic molecular theory for an ideal gas?

Accepted Answer

The masses of the particles are neglected.

Question 4

A blimp is filled with helium at $$20.0\ ^\circ\mathrm{C}$$, with a volume of $$2.00 	imes 10^7$ L and a pressure of 650 torr. How many moles of helium does it contain? (Use R = 0.0821$ L·atm/(mol·K), 1$ atm = 760$ torr)

Accepted Answer

$$7.1 	imes 10^5$ moles

Question 5

Three balloons are filled with CH$$_4 (16 g/$$mol), C$$_2H$_4 (28 g/$$mol), and O$$_2 (32 g/$$mol) at the same temperature, volume, and pressure. What is the order of the number of moles of gas in each balloon (more moles $$\u003e$$ fewer moles)?

Accepted Answer

CH$$_4$$ $$\u003e C$_2H$_4$$ $$\u003e O$_2$$

Question 6

What is the order of the densities of the three gases in the previous question (less dense $$\u003c$$ more dense)?

Accepted Answer

CH$$_4$$ $$\u003c C$_2H$_4$$ $$\u003c O$_2$$

Question 7

What is the order of the average kinetic energies of the three gases (slower $$\u003c$$ faster)?

Accepted Answer

All three molecules have the same average kinetic energy

Question 8

What is the order of the average molecular speed of the three gases (slower $$\u003c$$ faster)?

Accepted Answer

O$$_2$$ $$\u003c C$_2H$_4$$ $$\u003c CH$_4$$

Question 9

A mixture contains 12.0 g of He (4.00 g/mol) and 12.0 g of O$$_2 (32.0 g/$$mol) with a total pressure of 2.00 atm. What is the mole fraction and partial pressure of helium in this mixture?

Accepted Answer

0.500, 1.00 atm

Question 10

What is the root mean square (rms) speed of O$$_2$$ molecules (32 g/mol) in air at $$25\ ^\circ\mathrm{C}$$? Use $$R = 8.314 J/($$mol·K).

Accepted Answer

$$482 m/s$$

Question 11

Suppose that 0.00150 moles of CO$$_2 (44.0 g/$$mol) effuse out of a pinhole in 1.00 hour. How many moles of N$$_2 (28.0 g/$$mol) would effuse out of the same pinhole in 1.00 hour? (Assume both gases are at the same temperature and pressure.)

Accepted Answer

$$0.00188$$ mol

Question 12

You have 100. mL of a 0.60 M NaCl solution. How would you dilute it to 0.20 M?

Accepted Answer

Add 200. mL of water

Question 13

Calculate the molarity of a solution formed by dissolving 21.1 grams of KI (166.0 g/mol) in enough water to make 500. mL of solution.

Accepted Answer

$$0.254 M$$

Question 14

Calculate the mass of CO$$_2$$ produced when 100.0 grams of butane (C$$_4H$_{10}$$, 58.1 g/mol) is combusted in excess oxygen. The balanced equation is: $$2\ \mathrm{C}_4\mathrm{H}_{10}(g) + 13\ \mathrm{O}_2(g) \rightarrow 8\ \mathrm{CO}_2(g) + 10\ \mathrm{H}_2\mathrm{O}(g) (CO$_2 = 44.0 g/$$mol).

Accepted Answer

$$303 g$$

Question 15

Which of the following is the correct number of protons, neutrons, and electrons for the isotope $$^{25}Mg$$?

Accepted Answer

12 protons, 13 neutrons, 12 electrons

Question 16

Which of the following best describes the relationship between the Celsius and Kelvin temperature scales?

Accepted Answer

$$T_{\mathrm{K}} = T_{\mathrm{C}} + 273.15$$

Question 17

Which of the following is the correct value for the universal gas constant $$R in $$units of L·atm/(mol·K)?

Accepted Answer

$$0.0821$$\ \mathrm{L\cdot atm/(mol\cdot K)}$

General Chemistry Exam 1 Study Guidance: Gases, Kinetic Theory, and Foundational Concepts

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