Question

change in amount NH3 mol

Answer 1

Do you mean the change in the number of moles of NH3 in a chemical reaction? If so, use the extent of reaction (ξ) and the stoichiometric coefficient.

General formula:
- For a reaction written in standard form, n_i = n_i,0 + ν_i·ξ
- n_i = final moles of species i
- n_i,0 = initial moles of species i
- ν_i = stoichiometric coefficient of i (positive for products, negative for reactants)
- ξ = extent of reaction (moles of reaction progress)

So for NH3:
- Δn(NH3) = n_NH3 − n_NH3,0 = ν_NH3 · ξ

Example (Haber process): N2 + 3 H2 ⇌ 2 NH3
- ν_NH3 = +2, so Δn(NH3) = 2·ξ
- If ξ = 0.5 mol (reaction proceeds 0.5 mol), Δn(NH3) = 1.0 mol (1.0 mol NH3 formed).

Notes:
- If you want concentration change, divide Δn by volume V: Δ[NH3] = Δn(NH3)/V.
- If you have initial amounts and want ξ, determine the limiting reagent or solve stoichiometric balance.

If you give the reaction and initial moles (or ξ), I can compute the numeric change for you.