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yohanes775
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Homework Statement
The helium in the cylinder has a volume of 6.0 × 10^–3 m3^-1 (0.0060 m^3) and is at a pressure of 2.75 × 10^6 Pa.
(i) The pressure of helium in each balloon is 1.1 × 10^5 Pa. The volume of helium in an inflated balloon is 3.0 × 10^–3 (0.0030 m3). The temperature of the helium does not change. Calculate the number of balloons that were inflated.
Homework Equations
The Attempt at a Solution
so basically using P1V1=P2V2 :
=> [1.1 x 10^5] [Vᵢ ] = [2.75 x 10^6] [6x10^(-3)]
=> Vᵢ = [2.75 x 10^6] [6x10^(-3)] / [1.1 x 10^5] m³
so Vᵢ = 15 x 10^(-2) m³ or 0.15 m³
# of balloons = 15 x 10^(-2) m³ / vol. of 1 balloon = 15 x 10^(-2) m³ / [3 x 10^(-3)] m³
which should be 50 balloons
HOWEVER the answer is 48 balloons as one has to assume the cylinder doesn't fully empty and still holds helium at [1.1 x 10^5] Pa hence [6x10^(-3)] volume equivalent to 2 balloons would still remain in the cylinder at the balloon pressure hence Ans: is 50 - 2 = 48 balloons
but how can you assume the cylinder is still at 1.1 x 10^5 pascals? Basically what's the logic behind the last step?
Thanks!