How many grams of water will be produced from 32 grams of oxygen gas

Question

how do I set up the problem

Answer 1

The underlying chemical equation here is

2H2 + O2 ---> 2H20 , which you can use to figure out what the mole ratio is between compounds

In this case we have 32 g / 32 g/mol = 1.0 mol of O2 and the ratio between O2 and H2O from the equation is 2:1, meaning that

Moles H2O = 1.0 mol O2 x 2 mol H2O / 1 mol O2 = 2.0 mol H2O

Finally then you want to convert that value over into grams by multiplying by the Molar Mass

2.0 mol H2O x 18.02 g/mol = 36.04 g

meaning that this scenario will produce 36.04 grams of water

Answer 2

2H2 + O2 -> 2H20 is the balanced equation for the reaction of Hydrogen with Oxygen to form water so

 

If you have 32g of O2 this is a simple Dimensional analysis problem

 

32g O2 x 36.03056g H20/31.9988g O2 this way the O2 cancels out and you are left with just the H2O so your raw answer would be 36.0319112, then if your instructor requires a significant figure answer that would be to 2 significant figures the information you were given 32g O2, so as above 36g or Water are produced. Just a different way to view and solve the problem with the balanced equation so you can see the way everything relates to everything else. the molar masses of O2 and H2O are simply found my adding up 2 Oxygens 15.9994g x2 = 31.9988g and H2O = 2(1.00794) + 15.9994 = 18.01258 but you then have to multiply that by 2 because the reaction states you get 2 mols in the reaction so that is where I came up with the 36.03056g for the solution. Hope this helps. Dimensional Analysis is and can be one of the best ways to solve these problems, because not always are you going to be dealing with 1:2 ratios. 

Answer 3

Hey Alanni -- H2O pairs 2H with O ... O:16, H:1 ... O/H2O = 16/18 ... 32/36 => 36g water :)