3. a sample of octane (c3h18) gas has a mass of 1.135 g at a volume of 400. cm'3 and a temperature
of 200.°с. what is the pressure of the gas?

9.65 atm

Explanation:

From the question, we are given;

Mass of  octane is 1.135 gVolume of octane is 400 cm³ or 0.4 LTemperature of octane is 200°C

       But, K = °C + 273.15

Therefore, the temperature is equivalent to 473.15 K

We are required to calculate the pressure of the gas.

To do this, we are going to use the ideal gas equation;

According to the ideal gas equation;PV = nRT, where n is the number of moles, R is the ideal gas constant, 0.082057 L.atm/mol.KWe can rearrange the formula to calculate the pressure;

P = nRT ÷ V

But, n is the number of moles;Moles = Mass ÷ Molar massMolar mass of octane is 114.23 g/molMoles of octane = 1.135 g ÷ 114.23 g/mol

                                    = 0.00994 moles

Therefore;

P = 9.65 atm

Thus, the pressure of the gas is 9.65 atm

Elias is almost correct. he just got it backwards.the correct answer is that it demonstrates elastic potential energy transforming into kinetic energy.