Question

calculate the sound speed in helium gas at 440K​

Answer 1

Answer:

v=

M

rRT

M=

n

1

+n

2

n

1

M

1

+n

2

M

2

=(1×4+2×32)/(1+2)

=68/3×10

−3

kg/mol

For mixture;

C

v

=

n

1

+n

2

n

1

Cv

1

+n

2

Cv

2

C

v

for helium =3R/2

C

v

for oxygen =5R/2

C−v(1×3R/2+2×5R/2)/(1+2)=13R/6

C

p

=C

v

+R=R+13R/6=19R/6

Now,

Y

mix

=C

p

/C

v

=19/13

V

mix

=0.068/3kg/mol

Now, speed of sound in mixture =

3

68

×10

−3

13

19

×

3

25

×300

=400.9m/s