How many grams of H2O are in 34.2 grams of NAOH
Need ASAP

15.438g H2O

Explanation:

First you need to find the reaction equation:

2H2O+2Na=2NaOH + H2

Hydrogen is a diatomic molecule so it will have a subscript of 2 on the right hand side. From there we can balance the reaction.    

Then we can use stoichiometry:

34.2g NaOH * (1 mol NaOH/39.908g NaOH) * (2 mol H2O/2 mol NaOH) * (18.015g H2O/1 mol H20) = 15.438g H2O

It is important that when you use stoichiometry that all your units cancel out until you only have the unit you want.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2