Question

A Bottle of compressed nitrogen is used in your laboratory to flush the CVD furnace. If you received the 20-liter bottle at room temperature (25°C) and 10 MPa. After the slow release of nitrogen (isothermal), estimate the pressure if you have disbursed 1 kg.

* 2 points

4 MPa

5 MPa

5.6 MPa

4.4 MPa

Other:

Answer 1

Here we will use Ideal gas equation,

P*V = n*R*T _____________________________relation 1

P = Pressure inside bottle

V = Volume of water

R = Gas constant =

T = Temperatore of nitrogen

n = number of moles of nitrogen

Let P1, V1 ,T1and n1 be initial values (before releasing 1 kg of nitrogen) of Pressure , Volume, Temperature and number of moles of nitrogen respectively

and P2, V2, T2 and n2 be final values (after releasing 1 kg of nitrogen) of Pressure , Volume,Temperature and number of moles of nitrogen respectively

so, relation 1 give two equations

P1*V1 = n1*R*T1

and

P2*V2 = n2*R*T2

Since the process is isothermal T1 = T2 = T

and Volume does not change V1 = V2 = V

Subtracting P1*V1 = n1*R*T1 from P2*V2 = n2*R*T2

we get

( P2 - P1 )*V = ( n2 - n1 )*R*T

so

________________________________ relation 2

since number of moles n =Total mass / molecular mass

so

n2 - n1 =

using relation 1

we get