4. An inflated balloon has a volume of 6.0 L at sea level (1.0 atm) and is allow

Question

4. An inflated balloon has a volume of 6.0 L at sea level (1.0 atm) and is allowed to ascend until the pressure is 0.45 atm. During the ascent, the temperature drops from 22 °C to-21 What is the volume of the balloon at the final altitude? 5. The following reaction is used to inflate life rafts Callds) + 2H2O(l) Ca(OHHaq) + 2H2 (g) How many grams of Caly are needed to generate 145.0 L of H: gas at 0.997 atm and 20.0 ? 6. To identify the contents of an unlabeled cylinder of gas, a sample was collected and found to have a density of 5.38 gL at 150°C and 736.0 mnnHg pressure. What is the molar mass of the gas?

Explanation / Answer

initial                         final
P1 = 1atm                      P2 = 0.45atm
T1   = 22+ 273 = 295K           T2 = -21+273   = 252K
V1    = 6L                       V2 =
           P1V1/T1   =    P2V2/T2
              V2     =    P1V1T2/P2T1
                     =    1*6*252/0.45*295
                     = 11.4L
5.PV = nRT
   P = 0.997atm
   V   = 145 L
   T   = 20+273 = 293K
   n   = PV/RT
       = 0.997*145/0.0821*293 = 6 moles
CaH2(s) + 2H2O(l) ---------> Ca(OH)2(aq) + 2H2(g)
2 moles of H2 produced from 1 moles of CaH2
6 moles of H2 produced from = 1*6/2 = 3 moles of CaH2
mass of CaH2 = no of moles * gram molar mass
                = 3 *42 = 126g >>>answer

6. PM = dRT
    P = 736/760 = 0.97atm
    T = 15+273   = 288K
    d   = 5.38g/L
    M = dRT/P
       = 5.38*0.0821*288/0.97   = 131.14g/mole

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