A gas sample is known to be a mixture of ethane and butane. A bulb having a 230.0-cm3 capacity is filled with the gas to a pressure of 97.5 × 103 Pa at 23.1oC. If the weight of the gas in the bulb is 0.3554 g, what is the mole percent of butane in the mixture? Hint: Set up two equations to solve simultaneously for the two unknowns, the moles of ethane and butane.