Hydrogen and oxygen react to produce water, according to the reaction 2 H2 9) + O2(9) -- 2 H20 (1)
If 3 moles of hydrogen react with 2 moles of oxygen and the yield in the reaction is 80%, how many moles of water are obtained?

Dumbledore decides to gives a surprise demonstration. he starts with a hydrate of na2co3 which has a mass of 4.31 g before heating. after he heats it he finds the mass of the anhydrous compound is found to be 3.22 g. he asks everyone in class to determine the integer x in the hydrate: na2co3·xh2o; you should do this also. round your answer to the nearest integ