I have an assignment due in later today, but I can't understand how to do Moles! I've done most of the questions apart from the last two and I'm starting to get into a panic!!

Lithium and water reaction:

100cm3 water
0.12 g lithium added together made 171cm3 of H2

I found 0.01425 moles of lithium and 0.007125 moles of H2.

using the equation:
2Li + 2 H2O = 2LiOH + H2

I found that 0.15 moles of HCL was used, and 0.12 moles of LiOH was used as it is a 1:1 ratio.

The problem I'm having is with this questions:

calculate the number of moles of LiOH present in 100cm3 of the soloution

anduse this result and original mass of the lithium (0.12g) to calculate the relative atomic mass of lithium.

If anyone can help, i'd much appreciate it! I'll be back later on to see if theres any replies...please, I'm desperate, its taken me weeks to do this and I really cant afford to fall at the last part!

Thank you so much if you can help!

Amolo ( aka a very desperate AS Chemistry pupil!)