Most explosives are compounds that can produce a large quantity of gas in a confined space in a short period of time. Suppose that a cannon is charged with sufficient gunpowder to produce 12.5 moles of gas inside a 521 mL chamber. If the temperature in the chamber is 103 °C after the charge is ignited, what is the pressure, in atmospheres, behind the cannonball when the gunpowder goes off?