Answer and Explanation:
For each reaction, it is useful to detail which are the <u>reactants (</u>left side of the equation<u>)</u> and which are the products (right side of the equation), to deduce the chemical formulas.
1. Solid lithium reacts with water to produce hydrogen gas and a solution of lithium hydroxide.
<u>Reactants</u>: lithium element in solid-state (Li(s)) and water (H₂O) in the liquid-state. <u>Products</u>: hydrogen gas which is a diatomic molecule (H₂) and lithium hydroxide, which is a base formed by lithium cation Li⁺ and OH⁻ anion (LiOH).
Li(s) + H₂O(l) → H₂(g) + LiOH(aq)
2. Solid sodium reacts with gaseous chlorine to produce sodium chloride.
<u>Reactants</u>: sodium metal in solid-state (Na(s)) and chlorine which is a diatomic gas (Cl₂). <u>Products</u>: sodium chloride, which is a salt formed by sodium and chloride together (NaCl).
Na(s) + Cl₂(g) → NaCl(s)
3. Solid calcium carbonate breaks down into carbon dioxide gas, oxygen gas, and solid calcium.
It is a decomposition reaction, so we have only one reactant: calcium carbonate, which is a salt composed of carbonate anion (CO₃⁻²) and calcium ion (Ca²⁺). <u>Products</u>: carbon dioxide (CO₂), oxygen gas which is diatomic (O₂), and solid calcium (Ca(s)).
CaCO₃(s) → CO₂(g) + O₂(g) + Ca(s)
4. Solid iron(II) sulfate and a solution of barium chloride react to form solid barium sulfate and a solution of iron (II) chloride.
<u>Reactants</u>: iron(II) sulfate which is an ionic compound formed by the sulfate ion (SO₄²⁻) and iron ion (with two positive charges: Fe²⁺), and barium chloride which is a salt of barium ion (Ba²⁺) and two chloride ions (Cl⁻). <u>Products</u>: the salts formed by ion exchange, barium sulfate (BaSO₄), and iron (II) chloride (FeCl₂).
FeSO₄(s) + BaCl₂(aq) → BaSO₄(s) + FeCl₂(aq)
5. Solutions of hydrochloric acid and sodium hydroxide react to produce liquid water with sodium chloride dissolved in it.
It is the classical neutralization reaction. <u>Reactants</u>: hydrochloric acid (HCl) and the strong base sodium hydroxide (NaOH). <u>Products</u>: water (H₂O) and the salt formed by the anion provided by the acid (Cl⁻) and the cation provided by the base (Na⁺): NaCl.
HCl(aq) + NaOH(aq) → H₂O(l) + NaCl(aq)