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? (1 atm = 760 mm Hg)

Accepted Answer

$$0.97$$ atm

Question 2

Refer to the second image (Charles' Law graph). Which statement is TRUE about the data shown?

Accepted Answer

These data 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 $$20.0^\circC$$, with a volume of $$2.00 	imes 10^7$ L and a pressure of 650 torr. How many moles of helium does it contain? (R = 0.0821$ L·atm/(mol·K))

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. Which balloon contains the greatest number of moles of gas?

Accepted Answer

CH$$_4$$

Question 6

Which of the following gases will have the highest density under identical conditions of temperature and pressure: CH$$_4$$, C$$_2H$_4$$, or O$$_2$$?

Accepted Answer

O$$_2$$

Question 7

Which of the following gases will have the highest average molecular speed at the same temperature: CH$$_4$$, C$$_2H$_4$$, or O$$_2$$?

Accepted Answer

CH$$_4$$

Question 8

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?

Accepted Answer

Mole fraction: $$0.500$$, Partial pressure: $$1.00$$ atm

Question 9

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

Accepted Answer

$$482 m/s$$

Question 10

Suppose 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 in the same time under identical conditions?

Accepted Answer

$$0.00188$$ mol

Question 11

You have 100. mL of a 0.60 M NaCl solution. How much water must you add to dilute it to 0.20 M?

Accepted Answer

Add 200. mL of water

Question 12

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

Accepted Answer

$$0.254 M$$

Question 13

How many grams of CO$$_2$$ are produced from the complete combustion of 100.0 g of butane (C$$_4H$_{10}$$, 58.1 g/mol) in excess oxygen? (Balanced equation: $$2\ \mathrm{C}_4\mathrm{H}_{10} + 13\ \mathrm{O}_2 \rightarrow 8\ \mathrm{CO}_2 + 10\ \mathrm{H}_2\mathrm{O}$$, CO$$_2 = 44.0 g/$$mol)

Accepted Answer

$$303 g$$

Question 14

Which of the following is a correct statement about the average kinetic energy of gas molecules at the same temperature?

Accepted Answer

All gases have the same average kinetic energy at the same temperature.

Question 15

Which of the following is the correct order of average molecular speed for CH$$_4$$, C$$_2H$_4$$, and O$$_2 at $$the same temperature?

Accepted Answer

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

Question 16

Which of the following is the correct number of protons, neutrons, and electrons for $$^{25}Mg $$and $$^{26}Mg$$?

Accepted Answer

$$^{25}\mathrm{Mg}$$: 12p, 13n, 12e; $$^{26}\mathrm{Mg}$$: 12p, 14n, 12e

Step-by-Step Guidance for Chem 1071 Exam 1 (Chapters 1–5)

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