## Chemistry: The Molecular Science (5th Edition)

$CaF_2(s) + H_2SO_4(aq) -- \gt 2HF(g) + CaSO_4(s)$ $CaF_2$: Calcium fluoride; $H_2SO_4$: Dihydrogen sulfate or Sulfuric acid; $HF$: Hydrogen fluoride or Hydrofluoric acid; $CaSO_4$: Calcium sulfate.
1. Balance the reaction: - This is a double displacement reaction. - Analyzing the initial number of each ion in each side: $CaF_2(s) + H_2SO_4(aq) -- \gt HF(g) + CaSO_4(s)$ $Ca^{2+}$ : 1 and 1 - Balanced. $F^-$ : 2 and 1 - Not balanced. $H^+$: 2 and 1 - Not balanced. $SO_4^{2-}$: 1 and 1 - Balanced. Therefore, we just need to add a hydrogen and a fluoride to the products side, and we can do that by adding one more $HF$: $CaF_2(s) + H_2SO_4(aq) -- \gt 2HF(g) + CaSO_4(s)$ Since that did not effect anything else, the reaction is balanced. 2. Name the compounds: Since all the compounds are ionic: - Identify the cation; its name will be the first name of the compound. - Identify the anion; its name will be the second name of the compound. For $H_2SO_4$, the hydrogen will receive a "di", because this compound has 2 $H^+$.