Les réactions suivantes, qui ont toutes lieu en milieu...

Les réactions suivantes, qui ont toutes lieu en milieu aqueux, sont-elles des réactions acidobasiques, au sens de Brönsted? Si oui, écrivez les équations stœchiométriques des deux demi-réactions dont elles résultent. a) $2 \mathrm{HCl}+\mathrm{Zn}(\mathrm{s})=\mathrm{ZnCl}_2+\mathrm{H}_2(\mathrm{~g})$ b) $\mathrm{FeCl}_2+2 \mathrm{NaOH}=\mathrm{Fe}(\mathrm{OH})_2(\mathrm{~s})+2 \mathrm{NaCl}$ c) $\mathrm{NH}_4 \mathrm{Cl}+\mathrm{NaOH}=\mathrm{NH}_3+\mathrm{H}_2 \mathrm{O}+\mathrm{NaCl}$ d) $\mathrm{H}_2 \mathrm{~S}+\mathrm{Na}_2 \mathrm{CO}_3=\mathrm{NaHS}+\mathrm{NaHCO}_3$ e) $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{Na}+\mathrm{H}_2 \mathrm{O}=\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}+\mathrm{NaOH}$ f) $\mathrm{AgNO}_3+\mathrm{HCl}=\mathrm{AgCl}$ (s) $+\mathrm{HNO}_3$ g) $\mathrm{CaC}_2(\mathrm{~s})+2 \mathrm{H}_2 \mathrm{O}=\mathrm{C}_2 \mathrm{H}_2+\mathrm{Ca}(\mathrm{OH})_2$ h) $\mathrm{NaH}(\mathrm{s})+\mathrm{H}_2 \mathrm{O}=\mathrm{NaOH}+\mathrm{H}_2$

Les réactions suivantes, qui ont toutes lieu en milieu aqueux, sont-elles des réactions acidobasiques, au sens de Brönsted? Si oui, écrivez les équations stœchiométriques des deux demi-réactions dont elles résultent.
a) $2 \mathrm{HCl}+\mathrm{Zn}(\mathrm{s})=\mathrm{ZnCl}_2+\mathrm{H}_2(\mathrm{~g})$
b) $\mathrm{FeCl}_2+2 \mathrm{NaOH}=\mathrm{Fe}(\mathrm{OH})_2(\mathrm{~s})+2 \mathrm{NaCl}$
c) $\mathrm{NH}_4 \mathrm{Cl}+\mathrm{NaOH}=\mathrm{NH}_3+\mathrm{H}_2 \mathrm{O}+\mathrm{NaCl}$
d) $\mathrm{H}_2 \mathrm{~S}+\mathrm{Na}_2 \mathrm{CO}_3=\mathrm{NaHS}+\mathrm{NaHCO}_3$
e) $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{Na}+\mathrm{H}_2 \mathrm{O}=\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}+\mathrm{NaOH}$
f) $\mathrm{AgNO}_3+\mathrm{HCl}=\mathrm{AgCl}$ (s) $+\mathrm{HNO}_3$
g) $\mathrm{CaC}_2(\mathrm{~s})+2 \mathrm{H}_2 \mathrm{O}=\mathrm{C}_2 \mathrm{H}_2+\mathrm{Ca}(\mathrm{OH})_2$
h) $\mathrm{NaH}(\mathrm{s})+\mathrm{H}_2 \mathrm{O}=\mathrm{NaOH}+\mathrm{H}_2$

Key Concepts

Stoichiometric Balancing

This concept involves ensuring that both the atoms and the charge are balanced in chemical equations. It is crucial when writing half-reactions to accurately reflect the conservation of mass and charge, as well as the correct mole ratios in acid-base processes.

Role of the Solvent (Water)

Water, being amphoteric, can act as either a proton donor or acceptor, which makes it a common medium for acid-base reactions. Its unique properties facilitate the proton transfer process and influence the behavior of the reactants in aqueous systems.

Half-Reaction Equations

In the context of identifying acid-base reactions, the overall reaction can often be split into two half-reactions that separately represent the loss of a proton from the acid and the gain of a proton by the base. These half-reactions are key tools in studying the underlying proton exchange dynamics.

Proton Transfer Mechanism

Central to acid-base reactions is the movement of protons from the acid to the base. Understanding which species donate or accept protons allows one to break down the overall reaction into two half?reactions, corresponding to the donation and acceptance of protons.

Brönsted-Lowry Acid-Base Theory

This concept defines acids as proton donors and bases as proton acceptors. It focuses on the transfer of protons (H? ions) rather than the redistribution of electrons, which is the foundation for identifying whether a reaction qualifies as acidobasic under Brönsted’s interpretation.

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