Chemically reaction doubt ?

Question

The removal of H2S of LPG(natural gas) can be made through treatment with aqueous solution to 20% by mass of diethanolamine (DEA) reaction as below: (see the link)

http://img244.imageshack.us/img244/3600/imagem1jo2.png

Knowing that were used an excess of 100% of the base and a system without recycle, the mass of the solution of DEA, in Kg, put to react with 10 moles of H2S is:

Masses molars: in g / mole, H = 1, C = 12, N = 14, O = 16, S = 32

The answer is 10.5 (how come this answer)

Answer 1

DEA= 105 gm/mol

1 DEA + 1H2S --> 1 DEAH*HS

10 moles of H2S will react with 10 moles of DEA

10 moles of DEA= 10 mol * 105 gm/mol= 1050 gms DEA= 1.05 kgDEA

1.05 kg in a 20% solution

mass of solution= 1.05/.2= 5.25 moles DEA reacted

Have 100% excess, so total mass of DEA solution

= 5.25 x 2= 10.5 kg