What is the density of helium gas at 17 degrees celcius and 773 torr?

0.172g/L

Explanation:

Step 1:

Data obtained from the question:

Temperature (T) = 17°C

Pressure (P) = 773 torr

Step 2:

Conversion to appropriate unit:

For pressure :

760 torr = 1 atm

Therefore, 773 torr = 773/760 = 1.02 atm

For temperature:

Temperature (Kelvin) = temperature (celsius) + 273

temperature (celsius) = 17°C

Temperature (Kelvin) = 17°C + 273 = 290K.

Step 3:

Obtaining an expression for the density.

From the ideal gas equation PV = nRT, we can obtain an equation for the density as follow:

PV = nRT. (1)

But: number of mole(n) = mass (m)/Molar Mass(M) i.e

n = m/M

Substitute the value of n into equation 1

PV = nRT

PV = mRT/M

Divide both side by m

PV /m = RT/M

Divide both side by P

V/m = RT/MP

Invert the above equation

m/V = MP/RT (2)

Recall:

density (d) = mass(m) / volume(V) i.e

d = m/V

Replace m/V in equation 2 with d

m/V = MP/RT

d = MP/RT.

Step 4:

Determination of the density.

Temperature (T) = 290K

Pressure (P) = 1.02 atm

Molar Mass of helium (M) = 4g/mol

Gas constant (R) = 0.082atm.L/Kmol

Density (d) =?

d = MP/RT

d = 4 x 1.02 / 0.082 x 290

d = 0.172g/L

Therefore, the density of the helium gas is 0.172g/L

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.