Lithium metal decomposes in water and releases hydrogen gas. if 275 ml of hydrogen gas is produced at stp. what is the mass of lithium that reacted ? Li(s)+H2O(l)=LiOH(aq)+H2(g)

Answer 1

Convert 275 mL H2 gas at STP to mols.
275/22,400 = ??
Use the coefficients to convert mols H2 to mols Li.
Then g Li = mols Li x atomic mass Li.

Answer 2

0.171 g Li