AP Chem. How do I proceed? I am clueless!

Test Preparation AP Test Preparation
1

<li>You have a helium balloon at 1.00 atm and 25deg C. You want to make a hot-air balloon with the same volume and same lift as the helium balloon. Assume air is 79.0% nitrogen, 21.0% oxygen by volume. The “lift” of a balloon is given by the difference between the mass of air displaced by the balloon and the mass of the gas inside the balloon.</li>
</ol>

<p>b. Calculate the temperature of the air required for the hot-air balloon to provide the same lift as the helium balloon at 1.00 atm and 25deg C. Assume atmospheric conditions are 1.00 atm and 25deg C.</p>

2

<p>123.b.</p>

<p>0.79(28.02g) + 0.21(32g) = 28.9g Air</p>

<p>d = (molar mass He2)P/RT = (4g He2)(1.00atm)/(0.08206)(298K) = 0.16g/L He2
T = (molar mass Air)P/dR = (28.9g Air)(1.00atm)/0.16g/L He2)(0.08206) = 2150K</p>