Chemistry, 25.02.2020 04:28, claytonhopkins

If the sign contains neon at a pressure of 1.75 torrtorr at 38 ∘C∘C, how many grams of neon are in the sign? (The volume of a cylinder is πr2hπr2h.) Express your answer using two significant figures.

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answered: jason9394

The question is incomplete, here is the complete 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 1.75 torr at 38°C, how many grams of neon are in the sign? (The volume of a cylinder is πr²h.) Express your answer using two significant figures.

The mass of neon in the sign is $4.8\times 10^{-3}g$

Explanation:

The equation used to calculate the volume of cylinder is:

$V=\pi r^2h$

where,

V = volume of neon sign

r = radius of the neon sign = $\frac{d}{2}=\frac{2.5cm}{2}=1.25cm=1.25\times 10^{-2}m$ (Conversion factor: 1 m = 100 cm)

h = length/ height of the neon sign = 5.5 m

Putting values in above equation, we get:

$V=(3.14)\times (1.25\times 10^{-2})^2\times 5.5\\\\V=2.69\times 10^{-3}m^3=2.69L$ (Conversion factor: 1m^3=1000L )

To calculate the number of moles, we use the equation given by ideal gas equation:

PV = nRT

Or,

$PV=\frac{w}{M}RT$

where,

P = Pressure of the gas = 1.75 torr

V = Volume of the gas = 2.69 L

w = Weight of the gas = ?

M = Molar mass of neon gas = 20 g/mol

R = Gas constant = $62.364\text{ L. torr }mol^{-1}K^{-1}$

T = Temperature of the gas = 38^oC=[38+273]K=311K

Putting values in above equation, we get:

$1.75torr\times 2.69L=\frac{w}{20g/mol}\times 62.364\text{ L. torr }mol^{-1}K^{-1}\times 311K\\\\w=\frac{1.75\times 2.69\times 20}{62.364\times 311}=4.8\times 10^{-3}g$

Hence, the mass of neon in the sign is $4.8\times 10^{-3}g$

answered: Guest

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.