Question

According to the equation 2Na + 2H2O mc012-1.jpg 2NaOH+H2, what mass of Na is required to yield 22.4 L of H2 at STP? (The atomic mass of Na is 22.99 u.)
1.00 g
2.00 g
23.0 g
46.0 g

Answer 1

2Na+2H2O-->2NaOH+H2
at STP The standard temperature is 273 K (0° Celsius) and the standard pressure is 1 atm pressure. At STP, one mole of gas occupies 22.4 L of volume (molar volume).
so number of moles of H2 is 1
look at the mole ratio of sodium to hydrogen its 2:1

Answer 2

2:1
x:1
x=1*2/1=2 moles of sodium
Number of moles=Mass(g)/Molar Mass(g/mol)