<p> Phy 122L/132L</p><p>Pre-Lab: Ideal Gas Law Name: ======Choose the best answer. See the lab manual for definitions of variables used in this lab. (20 pts total) 1. The volume of a fixed amount of ideal gas is directly proportional to its temperature when the pressure is held constant. Which law is this? [1 pt] a. Boyle’s law b. Charles’s law c. Ideal gas law d. State of gas law</p><p>2. The pressure of a fixed amount of an ideal gas is inversely proportional to the volume when the temperature is held constant. Which law is this? [1 pt] a. Boyle’s law b. Charles’s law c. Ideal gas law d. State of gas law</p><p>In our lab, we will use a 2-liter soda bottle and a PASCO tube to verify Boyle’s law. We can rearrange the Equation of State of an Ideal Gas to the following:  nRT  1 V  L      0  (eqn 4)  A  P  A </p><p> where V0 is the volume of the air in the 2-liter bottle plus the connecting tube, L is length PASCO tube; A is cross-sectional area of PASCO tube, and P is pressure. Questions 3-6 refer to a plot of air column length versus inverse pressure, L vs. 1/P.</p><p>3. Should the plot yield a curved line or a straight line? [1 pt] a. curved line b. straight line</p><p>4. What does the slope of the plot represent (what is it equal to symbolically)? [1 pt] 2 a. L b. 1/P c. nRT/A d. –V0/A e. V0/Af. (πD L)/4</p><p>5. What would the y-intercept represent (what is it equal to symbolically)? [1 pt] 2 a. L b. 1/P c. nRT/A d. –V0/A e. V0/Af. (πD L)/4</p><p>6. What should V0 be approximately equal to? [1 pt] a. 2000 ml b. 2x10-3 m3 c. 2 liters d. All of the above e. None of the above</p><p>7. In the Ideal Gas Law experiment, the volume of the air in the cylinder is changed by adding weights to the moveable piston. The piston itself has a mass of 35 grams with a diameter of 32.5 mm. For added weights of 0 g, 40 g, and 80 g, air column lengths of 81.9 mm, 69.8 mm, and 58.1 mm were recorded, respectively. Complete the following table. [6 pts] Area of Total Inverse Piston, A (m2): Weight on pressure of Length of pressure, Mass added, Total mass, air column, gas (air), air column, 1/P -6 2 Ma (kg) M (kg) W (N) P (Pa) L (m) x10 (m /N) 0.0 0.035 0.343 0.0819 9.95883 0.040 0.075 100885 0.0698 0.080 1.127 101358 9.86597 Total mass = added mass + mass of piston Weight on air column = M “g” 5 Pressure = P0 + M “g”/A (P0 = atmospheric pressure. Assume P0 = 1.000x10 Pa) A = area of piston = πD2/4 (D = diameter of piston in meters)</p><p>CSU Pomona Updated 01/02/09 Dr. Julie J. Nazareth Phy 122L/132L</p><p>The following applies to questions 8-10. Data from the previous table was used to make a graph of air column length versus inverse pressure (L vs. 1/P) using SI units. The origin was NOT included in the plot to maximize the spread between the data points. A best fit straight line was -6 -1 drawn and two easy to read points on the line were chosen: (x1, y1) = (9.8725x10 Pa , 0.060 m), -6 -1 (x2, y2) = (9.955x10 Pa , 0.081 m). Hint: questions 3-6 dealt with the same graph (L vs. 1/P), only theoretically. Note Pa-1 = 1/Pa = m2/N.</p><p>8. Use these points to calculate the slope and the y-intercept of the line. As always, don’t forget to include units in your calculations. [3 pts]</p><p>Slope = </p><p> y-intercept = </p><p>9. Use your value of the slope to calculate the number of moles of air in the lab apparatus. Assume the air temperature is 21°C. Show work (including units) to receive credit. [3 pts]</p><p>10. Use your value of the y-intercept to calculate the volume of the 2-liter soda bottle plus connecting hose. Show work (including units) to receive credit. [2 pts]</p><p>Derivation of equation 4 and comparison to equation of a straight line. (See lab manual for definition of variables)</p><p>P V = nRT where V = Vo + L A</p><p>Vo + LA = (1/P) nRT </p><p>L A = (1/P) nRT - Vo</p><p>L = nRT/A (1/P) + -Vo/A “y” = slope “x” + y-intercept</p><p>CSU Pomona Updated 01/02/09 Dr. Julie J. Nazareth</p>