Think about "The Law of Conservation of Mass" (In a chemical change, the total mass of the new substances is always the same as the total mass of the original substances.) Why might it be difficult to demonstrate this law in chemical changes where one or more of the products is a gas?

Quiz1. which physical state of nitrogen has the highest entropy? a solid© b gasoc liquid

For the reaction shown, calculate how many moles of no2 form when each of the following completely reacts. 2n2o5(g)→4no2(g)+o2(g) part a 1.0 mol n2o5 express your answer using two significant figures. nothing mol m o l request answer part b 5.4 mol n2o5 express your answer using two significant figures.

Fred is studying a substance that is made out of only one element. this means that