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Laboratory 14 A CAPSTONE EXPERIENCE: TOWARD THE CREATION OF AN AUTOMOBILE AIRBAG

Laboratory 14 A CAPSTONE EXPERIENCE: TOWARD THE CREATION OF AN AUTOMOBILE AIRBAG

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## Laboratory 14 A CAPSTONE EXPERIENCE: TOWARD THE CREATION OF AN AUTOMOBILE AIRBAG

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**Laboratory 14**A CAPSTONE EXPERIENCE: TOWARD THE CREATION OF AN AUTOMOBILE AIRBAG**Objectives**• Integrate general chemistry I concepts to create a model for an automobile airbag • Determine a method and then carry out appropriate procedures to inflate a bag with a gas, given a specified set of materials**THREE STATES OF MATTER**General Properties of Gases • There is a lot of “free” space in a gas. • Gases can be expanded infinitely. • Gases fill containers uniformly and completely. • Gases diffuse and mix rapidly.**Properties of Gases**• Gas properties can be modeled using math. Model depends on— • V = volume of the gas (L) • T = temperature (K) • n = amount (moles) • P = pressure (atmospheres)**The Ideal Gas Equation**Ideal gas law the functional relationship between the pressure, volume, temperature and moles of a gas. PV = nRT P = pressure V = volume T = temperature (Kelvin) n = number of moles R = gas constant**Standard molar volume of an ideal gas**The volume of 1 mol of an ideal gas under standard conditions, V = nRT = (1 mol) [0.082057 (L•atm)/(K•mol)] (273.15 K) = 22.41 L P 1 atm The volume of 1 mol of an ideal gas at 0ºC and 1 atm pressure is 22.41 L, called the standard molar volume of an ideal gas.**Using PV = nRT**How much N2 is required to fill a small room with a volume of 960 cubic feet (27,000 L) to 745 mm Hg at 25 oC?**Solution**• 1. Get all data into proper units • V = 27,000 L • T = 25 oC + 273 = 298 K • P = 745 mm Hg (1 atm/760 mm Hg) = 0.98 atm • R= 0.0821 L atm / mol K**Now plug in those values and solve for the unknown.**PV = nRT n = 1.1 x 103 mol (or about 30 kg of gas)**Importance of Gases**• Airbags fill with N2 gas in an accident. • Gas is generated by the decomposition of sodium azide, NaN3. • 2 NaN3 ---> 2 Na + 3 N2 • Electronic sensors built into the car detect collisions, and an electrical impulse is sent to the air bag, igniting it. • The air bag itself is made of nylon and contains very small pores, and will deflate soon after inflating to allow the passenger to exit the vehicle.**Your task is to simulate the construction of an air bag**using a ziplock bag, baking soda (NaHCO3) and acetic acid (HC2H3O2) The reaction produces , which inflates the ziplock bag. carbon dioxide gas NaHCO3(s) + HC2H3O2(aq) (baking soda) (acetic acid ) CO2(g) + NaC2H3O2(aq) + H2O(l)