Chemistry 14.3 Study Guide 3-8-13

Chemistry 14.3 Study Guide 3-8-13 **Make sure you have the following gas law formulas in your SIS before next week’s quiz: - Boyles Law - Charles Law - Gay-Lussac’s Law - Combined Gas Law - Ideal Gas Law (from today’s study guide)

in book

1. Explain what dry ice is and what it is used for. 2. What does the ‘dry’ in dry ice refer to? 3. Google the word sublimes and explain how it applies here. 4. Explain why dry ice can exist. 5. What is the benefit of the combined gas law? 6. What assumptions does the combined gas law make? 7. What can you NOT use the combined gas law for? 8. How will we calculate the number of moles of a gas? 9. What 2 things are the number moles of a gas proportional to? 10. Give the standard temperature and pressure (STP) of a gas and how many Liters in a mole. 11. What is the value given to ideal gas constant? 12. Explain what is meant by the ideal gas law. 13. Write the formula for the ideal gas law in your SIS (PV=nRT) 14. What do all the variables in this formula stand for?

**Look at the sample problem on page 427 then used the formula for an ideal gas to do the following problem right here:

When the temperature of a rigid hollow sphere containing 685L of helium gas is held at 621K the pressure of the gas is 1.89x 10^3 kPa. How many moles of helium does the sphere contain?

15. When is a gas considered an ideal gas? 16. Explain why an ideal gas probably does not exist. 17. How is a real gas different from an ideal one? 18. What is possible because of the attractions between gas particles? 19. When do real gases differ from ideal ones? 20. What happens to a gas as attractive forces reduce the distance between particles? **Look at the graph on page 429 to answer these questions: 21. What are the values of PV/nRT for an ideal gas at 20,000kPa? What about 60,000kPa? 22. What variable is responsible for the differences between the two methane (CH4) curves? 23. How does an increase in pressure affect the PV/nRT ratio for real gases?