1. Equal numbers of moles of Ar(g), Kr(g), and Xe(g) are placed in a rigid glass vessel at room temperature. If the container has a pin hole-sized leak, which of the following will be true regarding the relative values of the partial pressures of the remaining gases after some effusion has occurred?

2. Gases at 0°C and 1 atm.

3. Which of the following must be true of a pure, covalent solid heated slowly at its melting point until about half the compound has turned into liquid?

4. At STP, a 0.2-mol sample of CO2(g) and a separate 0.4-mol sample of N2O(g) have the same:

5. Which of the following is expected to have the highest boiling point based on the strength of intermolecular forces?

6. At the top of a high mountain, water boils at 90°C (instead of 100°C, the boiling point of water at sea level). Which of the following best explains this phenomenon?

7. In a laboratory experiment, a student reacts Na2CO3 (106 g mol−1) with HCl. Water displacement is used to measure the amount of CO2 produced (the gas over water is collect in a eudiometer). If the student reacts 10.6 g Na2CO3 in 250 ml of 2.50 M HCl, how many moles of CO2 gas would one expect to collect?

8. Gases at 0°C and 1 atm.

9. Three gases, 1.6 g He (4 g mol−1), 4 g Ar (40 g mol−1), and 26 g Xe (131 g mol−1), are added to a previously evacuated rigid container. If the total pressure in the tank is 2.1 atm, the partial pressure of Xe(g) is closest to:

10. A rigid metal container contains Ne gas. Which of the following is true of the gas in the tank when additional Ne is added at a constant temperature?

11. A 2-L container will hold approximately 3 grams of which of the following gases at 0°C and 1 atm?

12. Gases at 0°C and 1 atm.

13. Gases at 0°C and 1 atm.

14. Which of the following pure substances has the highest melting point?

15. A 2-L flask contains 0.50 mole of SO2(g), 0.75 mole of O2(g), 0.75 mole of CH4(g), and 1.00 mole CO2(g). The total pressure in the flask is 800 mmHg. What is the partial pressure of O2(g) in the flask?

16. In a laboratory experiment, a student reacts Na2CO3 (106 g mol−1) with HCl. Water displacement is used to measure the amount of CO2 produced (the gas over water is collect in a eudiometer). The total atmospheric pressure of the laboratory (760 mmHg), as well as the temperature of the water (22°C) and the volume of gas (502 mL) in the eudiometer, are known. Which additional data, if any, is needed to calculate the number of moles of CO2 gas collected during the experiment?

17. Gases at 0°C and 1 atm.

18. At 298 K and 1 atm, a 0.5-mol sample of O2(g) and a separate 0.75-mol sample of CO2(g) have the same:

19. The melting point of BeO is 2,507°C while the melting point of NaCl is 801°C. Explanations for this difference include which of the following? I. Be2+ is more positively charged than Na+. II. O2− is more negatively charged than Cl−. III. The Cl− ion is larger than the O2− ion.

20. Gases N2(g) and H2(g) are added to a previously evacuated container and react at a constant temperature according to the following chemical equation: If the initial pressure of N2(g) was 1.2 atm, and that of H2(g) was 3.8 atm, what is the partial pressure of NH3(g) when the partial pressure of N2(g) has decreased to 0.9 atm?

21. Which of the following gases behaves least ideally?

22. Under which of the following conditions do gases behave most ideally?

23. All of the following changes occur as H2O freezes except:

24. HCl and NH3 gases are released into opposite ends of a 1-meter (100-cm), vertical glass tube at 25° C. Their reaction quickly produces a white fog of ammonium chloride. If the two gases are released at exactly the same time, which of the following most closely approximates where the ammonium chloride fog would form?

25. Which of the following gases has the greatest average molecular speed at 298 K?