Asolution is made by dissolving 9.74 g of sodium sulfate in water to a final volume of 165 ml of solution. what is the weight/weight % or percent by mass of the solute?

Butane gas reacts with oxygen gas to give carbon dioxide gas and water vapor (gas). if you mix butane and oxygen in the correct stoichiometric ratio, and if the total pressure of the mixture is 390 mmhg, what is the pressure (in mmhg) of water vapor after the reaction is completed (temperature and volume do not change).