Question

what is the balanced chemical reaction occurring when zinc metal is added to hydrofluoric acid? partial activity series k ca mg al zn fe ni pb h cu ag f₂ cl₂ br₂ i₂ zn + hf → znh + f no reaction occurs. zn + hf → znf + h zn + 2hf → znf₂ + h₂

Explanation:

1. First, check the activity series: Zn is above H, so Zn can displace H from an acid (hydrofluoric acid, HF).
2. The reaction is a single - displacement reaction. Zinc (Zn) reacts with hydrofluoric acid (HF). The products should be zinc fluoride ($\ce{ZnF2}$) and hydrogen gas ($\ce{H2}$).
3. Now, balance the equation:

• On the left side, we have 1 Zn, 1 H, and 1 F from HF. But to balance F, we need 2 HF (since $\ce{ZnF2}$ has 2 F atoms).
• So the reaction is $\ce{Zn + 2HF -> ZnF2 + H2}$.
• Let's check the other options:
• $\ce{Zn + HF -> ZnH + F}$: Incorrect products (ZnH and F are not the correct products of Zn - HF reaction).
• "No reaction occurs": Incorrect because Zn is more reactive than H (from activity series), so reaction should occur.
• $\ce{Zn + HF -> ZnF + H}$: Incorrect products (ZnF is not the correct zinc fluoride formula, and H should be $\ce{H2}$ gas, also the formula is unbalanced).

Answer:

$\ce{Zn + 2HF -> ZnF2 + H2}$ (the option: $\boldsymbol{\ce{Zn + 2HF -> ZnF2 + H2}}$)