Answer: Number of molecules of hydrogen gas 
Explanation:
Number of moles of sodium =
According to reaction , 2 moles of sodium produces 1 mole of hydrogen gas , then 2.11 mol of sodium will= 
of hydrogen gas that is 1.05 moles of hydrogen gas.
Number of molecules = 
moles of substance
Moles of hydrogen gas formed = 1.05 moles
Number of molecules of hydrogen gas = 
moles of hydrogen gas
Number of molecules of hydrogen gas 
Answer:
you need to use the 2 because I already did it
Explanation:
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<span>Pre-1982 definition of STP: 37 g/mol
Post-1982 definition of STP: 38 g/mol
This problem is somewhat ambiguous because the definition of STP changed in 1982. Prior to 1982, the definition was 273.15 K at a pressure of 1 atmosphere (101325 Pascals). Since 1982, the definition is 273.15 K at a pressure of exactly 100000 Pascals). Because of those 2 different definitions, the volume of 1 mole of gas is either 22.414 Liters (pre 1982 definition), or 22.71098 liters (post 1982 definition). And finally, there's entirely too many text books out there that still use the 35 year obsolete definition. So let's solve this problem using both definitions and you need to pick the correct answer for the text book you're using.
First, determine how many moles of gas you have. Just simply divide the volume you have by the molar volume.
Pre-1982: 2.1 / 22.414 = 0.093691443 moles
Post-1982: 2.1 / 22.71098 = 0.092466287 moles
Now determine the molar mass. Simply divide the mass by the moles. So
Pre-1982: 3.5 g / 0.093691443 moles = 37.35666667 g/mol
Post-1982: 3.5 g / 0.092466287 moles = 37.85163333 g/mol
Finally, round to 2 significant figures. So
Pre-1982: 37 g/mol
Post-1982: 38 g/mol</span>
For every 3 Fe there is only 1 Fe3O4 producing.
So, ratio would be: Fe3O4 / Fe = 1 / 3
In short, Your Answer would be: 1 : 3
Hope this helps!
