how many ml of H are produced by the reaction of 0.75g of sodium metal with H2O?

Question

can any one help me with this

Answer 1

2 Na + 2 H2O --> 2 NaOH + H2

1) convert Na to moles
0.75 g x (1 mole Na / 23.0 g Na) = 0.033 mole Na

2) use the equation to convert mole Na to mole H2
0.033 mole Na x (1 mole H2 / 2 mole Na) = 0.017 mole H2

3) convert mole H2 to volume
0.017 mole H2 x (22.4 L H2 / 1 mole H2) = 0.38 L = 380 mL

note: this is the volume at STP (standard temperature and pressure)

Answer 2

You'd have to say at what temperature and pressure in order to solve the problem, and even then people here won't do your homework for you. EDIT: I take it back. Chem Geek will do your homework for you, apparently.

However, if you divide the mass of Na by its molecular weight, you'll have the number of moles of Na that react. Since the reaction is Na + H2O -> NaOH + 1/2(H2), each mole of Na that reacts gives half a mole of H2. Then you'd need a coversion from moles of H2 to volume of H2, which depends on temperature and pressure. At zero degrees and normal atmospheric pressure that's 22.4 L/mol. 1L=1000mL, and you should be able to solve the rest yourself. Chemists still use this to figure out if a reaction is complete. If you were doing a reaction where a gas is produced, you can trap the gas in a graduated cylinder inverted in a beaker full of water (with a tube leading the gas from the reaction flask to the inverted graduated cylinder). Once the expected volume of water has been displaced by the gas, your reaction is done.