A neon sign is made of glass tubing whose inside diameter is 2.5 cm and whose le

Question

A neon sign is made of glass tubing whose inside diameter is 2.5 cm and whose length is 5.5 m.

Part A

If the sign contains neon at a pressure of 1.77 torr at 31 C, how many grams of neon are in the sign? (The volume of a cylinder is r2h.)

Express your answer using two significant figures.

2.49{cdot}10^{4}

A neon sign is made of glass tubing whose inside diameter is 2.5 cm and whose length is 5.5 m.

Part A

If the sign contains neon at a pressure of 1.77 torr at 31 C, how many grams of neon are in the sign? (The volume of a cylinder is r2h.)

Express your answer using two significant figures.

2.49{cdot}10^{4}

Explanation / Answer

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

L = 5.5 m = 550 cm

volume = pi*r^2*L
= (3.14)*(1.25)^2*550
= 2700 cm^3
= 2700 mL
= 2.700 L

Given:
P = 1.77 torr
= (1.77/760) atm
= 0.00233 atm
V = 2.7 L
T = 31.0 oC
= (31.0+273) K
= 304 K

find number of moles using:
P * V = n*R*T
0.00233 atm * 2.7 L = n * 0.08206 atm.L/mol.K * 304 K
n = 2.521*10^-4 mol

Molar mass of Ne = 20.18 g/mol

use:
mass of Ne,
m = number of mol * molar mass
= 2.521*10^-4 mol * 20.18 g/mol
= 5.087*10^-3 g
Answer: 5.1*10^-3 g

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