How To Write Chemical Reactions - Chemistry Test

Explanation
In this chemical reaction, solid sodium (Na) reacts with a solution of magnesium fluoride (MgF2) to produce sodium fluoride solution (NaF) and solid magnesium (Mg). The reaction can be represented by the balanced chemical equation Na (s) + MgF2 (aq) ----> NaF (aq) + Mg (s).

Explanation
When magnesium metal is added to hydrochloric acid, a chemical reaction occurs. The magnesium atoms react with the hydrogen ions in the hydrochloric acid to form magnesium chloride, which is soluble in water, and hydrogen gas. This reaction is represented by the balanced chemical equation: Mg (s) + HCl (aq) → MgCl2 (aq) + H2 (g). In this reaction, the magnesium metal loses electrons and is oxidized, while the hydrogen ions gain electrons and are reduced. The formation of magnesium chloride and hydrogen gas is a result of the transfer of electrons between the magnesium and the hydrogen ions.

Explanation
Chlorine gas (Cl2) is added to a solution of potassium iodide (KI) to form potassium chloride (KCl) solution and iodine (I2) liquid. This reaction occurs because chlorine is more reactive than iodine and displaces it from the potassium iodide solution. The chlorine atoms combine with the potassium ions to form potassium chloride, while the iodine is released as a liquid.

Explanation
When sodium chloride crystals are heated, they undergo a chemical reaction and decompose into sodium powder and chlorine gas. This reaction can be represented by the equation NaCl (s) ---> Na (s) + Cl2 (g). The solid sodium chloride breaks down into solid sodium and gaseous chlorine molecules. This reaction occurs due to the high temperature, which provides the energy necessary to break the bonds between the sodium and chlorine atoms in the crystal lattice structure of sodium chloride.

Explanation
In this chemical equation, solid sodium (Na) is combined with gaseous oxygen (O2) to form an aqueous solution of sodium oxide (Na2O). The arrow represents the reaction, with the reactants on the left side and the product on the right side. This equation shows the balanced combination of sodium and oxygen atoms to form sodium oxide molecules in solution.

Explanation
When sodium crystals (Na) are combined with hydrochloric acid (HCl), a chemical reaction occurs. The sodium reacts with the hydrochloric acid to produce hydrogen gas (H2) and sodium chloride solution (NaCl). This reaction can be represented by the balanced chemical equation: Na (s) + HCl (aq) → H2(g) + NaCl(aq).

Explanation
In this reaction, solid potassium (K) reacts with gaseous chlorine (Cl2) to form an aqueous solution of potassium chloride (KCl). The arrow indicates the direction of the reaction, with the reactants on the left side and the product on the right side. The state symbols (s, g, aq) indicate the physical state of each substance: solid, gas, or aqueous solution.

Explanation
In this reaction, copper (II) oxide (CuO) in solution reacts with solid carbon (C) to produce copper metal (Cu) and carbon dioxide gas (CO2). This is a redox reaction where copper (II) oxide is reduced to copper metal, while carbon is oxidized to carbon dioxide. The balanced chemical equation represents the correct stoichiometry of the reaction, with one mole of CuO reacting with one mole of C to produce one mole of Cu and one mole of CO2.

Explanation
When calcium metal is combined with oxygen gas, a chemical reaction occurs and solid calcium oxide is formed. This reaction can be represented by the balanced chemical equation: Ca(s) + O2(g) ----> CaO(s). In this reaction, calcium atoms react with oxygen molecules to produce calcium oxide. The solid calcium oxide is formed as a result of the combination of calcium and oxygen atoms.