# Under what pressure is oxygen in the cylinder if at a temperature of 27 its density is 6.24.

Given:

t = 27 degrees;

P = 6.24 kg / m ^ 3;

Find: p.

Decision:

1) We will use the Clapeyron-Mendeleev formula:

pV = m / M * RT.

2) In order to find the required variable, we transform the equation. To do this, divide both parts by V.

We get: p = m / MV * RT.

We can further transform the equation. Due to the fact that the ratio of mass m to volume V is equal to the density of the gas P, then we get p = P / M * RT.

3) It is necessary to convert the temperature scale, for this we translate the temperature into an absolute temperature scale, then: 27 degrees = 300 K.

4) Substitute all the values in the formula and find the answer. We take into account that the molar mass of oxygen O2 is 0.032 kg / mol.

p = 6.24 / 0.032 * 8.31 * 300 = 486135 Pa. Round up to 0.49 MPa.

Answer: 0.49