Question

You are trying to determine the volume of the balloon needed to match the density of the air in the lab. You know that if you can get the balloon's density below this value, it will float. You measure both the temperature in the room as well as the mass of the balloon you will use and find they are 18.0°C and 0.577 grams, respectively. What volume of balloon will generate a density equal to that of the air around it? (Hint: Use the relationship you calculated above to determine the air density at the temperature given)
Balloon Volume Needed =

equation from problem 1 :y = -0.0043x + 1.2874

Answer 1

Answer is: volume of balloon is 476,85 cm³.
density of air: d(air) = -0,0043 · 18,0°C + 1,2874.
d(air) = 1,21 kg/m³ = 1,21 · 10³/ 10⁶ = 0,00121 g/cm³.
m(balloon) = 0,577 g.
d(balloon) = d(air).
d(balloon) = m(balloon) ÷ V(balloon).
V(balloon) = m(balloon) ÷ d(balloon)
V(balloon) = 0,577 g ÷ 0,00121 g/cm³.
V(balloon) = 476,85 cm³.