solution calculation chemistry

Whatmass of magnesium reacts with 100 cm³ of 2.0 mol/dm³ hydrochloric acid?
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

No. of moles of HCl reacted = 2.0 ´ (100/1000) = 0.2 mol
No. of moles of Mg reacted = 0.2 ´ (1/2) = 0.1 mol
Mass of Mg reacted = 0.1 ´ 24.3 = 2.43g


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What volume of 0.10 mol/dm³ sulphuric acid reacts with 1 g of zinc powder?
Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)

The equation should be :
Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g)

No. of moles of Zn = 1/65.4 = 0.0153 mol
No. of moles of H2SO4 = 0.0153 mol
Volume of H2SO4 = 0.0153/0.10 = 0.153 dm³ = 153cm³

2011-09-30 12:42:04 補充：
Answer to the last question :

Mass of NaOH = 0.1 x (28.2/1000) x (250/25) x (23 + 16 + 1) = 1.128 g