How many milliliters of sodium metal, with a density of 0.97 g/mL, would be needed to produce 12.8 grams of hydrogen gas in the single replacement reaction below? Show all steps of your calculation as well as the final answer.

unbalanced equation: Na + H2O - NaOH + H2

Question

How many milliliters of sodium metal, with a density of 0.97 g/mL, would be needed to produce 12.8 grams of hydrogen gas in the single replacement reaction below? Show all steps of your calculation as well as the final answer. 

unbalanced equation: Na + H2O -> NaOH + H2

aripotta · Answer

this is what i put:

2Na + 2H2O -> 2NaOH + H2 

12.8g H2 x [1 mol H2]/[2.0158g H2] x [2 mol Na]/[1 mol H2] x [22.989g Na]/[1 mol Na] x [1 mL Na]/[0.97g Na] = 301 mL Na 

301 milliliters of sodium metal would be needed to produce 12.8g of hydrogen gas.

i got a 0 on it, so i guess it's the wrong answer? can someone show me the correct answer?

aaronq · Answer

I think you should do this in steps, because it's more confusing for yourself, and for the person trying to decipher what you're doing.

moles H2= 12.8g H2 x [1 mol H2]/[2.0158g H2] = 6.4 moles

moles of H2/1=moles of Na/2  ->  6.4 moles*2=12.8 moles of Na

mass of Na = 12.8 moles of Na* [22.989g Na]/[1 mol Na]=294.2592 g

density=mass/V -> V =294.2592 g/0.97g/mL= 303.36 mL Na  

So i don't think there is anything wrong with it, unless you were supposed to round.

I rounded the molar mass of H2 to 2 g/mol, btw.