Question

A neon sign is made of glass tubing whose inside diameter is 2.5 cm and whose length is 5.5 m. If the sign contains neon at a pressure of 1.73 torr at 37 ∘C, how many grams of neon are in the sign? (The volume of a cylinder is πr2h.) Express your answer using two significant figures.

Answer 1

volume of a cylinder = πr²h

diameter = 2.5 cm then radius is 2.5/2 = 1.25 cm

height(length) = 5.5 m = 550 cm

volume = 3.14*(1.25cm)^2*550 cm

              = 2698.4 cm^3

              = 2698.4 mL

pressure = 1.73 torr = 0.002276 atm

Temperature = 37 + 273 = 310 K

PV = nRT

0.002276*2.6984 = n*(0.0821)*310

n = 0.000241 moles

molar mass of Neon = 20.18 g mol

mass of Neon = moles * molar mass

                         = 0.000241*20.18

                         = 0.00486 g

                         = 4.9*10^-3 g