Part B In an air-conditioned room at 19.0 C, a spherical balloon had the diamete
ID: 1072875 • Letter: P
Question
Part B
In an air-conditioned room at 19.0 C, a spherical balloon had the diameter of 50.0 cm. When taken outside on a hot summer day, the balloon expanded to 51.0 cm in diameter. What was the temperature outside? Assume that the balloon is a perfect sphere and that the pressure and number of moles of air molecules remains the same.
Express your answer numerically in degrees Celsius.
Part C
A cylinder with a movable piston contains 2.00 g of helium, He, at room temperature. More helium was added to the cylinder and the volume was adjusted so that the gas pressure remained the same. How many grams of helium were added to the cylinder if the volume was changed from 2.00 L to 3.30 L ? (The temperature was held constant.)
Express your answer numerically in grams.
V 3.00 L V-1.00 LExplanation / Answer
part A
from boyles law
P1V1 = P2V2
1.95*3 = P2*1
P2 = final pressure = 5.85 atm
part B
diameter (a1)= 50 cm
initial volume of sphere = v1 = 4/3*Pi*(50/2)^3
final volume of sphere = v2 = 4/3*Pi*(51/2)^3
V1/T1 = V2/T2
50/(19+273.15) = 51/(x+273.15)
x = temperature outside = T2 = 24.83 c
part C
no of mole of He present initially = n1 = 2/4 = 0.5 mole
no of mole of He present finally = n2 = ?
from avagadros law
v1/n1 = v2/n2
2/0.5 = 3.3/n2
n2 = 0.825 mole
amount of helium were added = (0.825-0.5)*4 = 1.3 g