Question

change in amount H2 mol

Answer 1

Do you mean the change in the amount (moles) of H2 during a chemical reaction? If so, here are the simple rules and examples — tell me the reaction and any initial amounts or the extent of reaction and I’ll compute it for you.

1) General formula using reaction extent (ξ)
- For a reaction written with stoichiometric coefficients (νi), the change in moles of species i is
Δn_i = ν_i · ξ
- ν_i is positive for products, negative for reactants.
- ξ (extent) is in moles.
- Final moles: n_i,final = n_i,initial + Δn_i.

2) Example 1 — N2 + 3 H2 → 2 NH3
- For H2, ν_H2 = −3 so Δn_H2 = −3 ξ.
- If ξ = 1.00 mol, Δn_H2 = −3.00 mol (H2 consumed). If initial H2 = 5.00 mol, final = 5.00 − 3.00 = 2.00 mol.

3) Example 2 — H2 produced (e.g., Zn + 2 HCl → ZnCl2 + H2)
- ν_H2 = +1 so Δn_H2 = +1 · ξ.
- If ξ = 0.50 mol, Δn_H2 = +0.50 mol.

If you give the balanced equation and either the extent ξ or the initial/final amounts (or percent conversion), I’ll do the specific calculation.