Complete and balance the following: (a) \(\operatorname{As}(s)+\) excess \(\mathrm{O}_{2}(g) \longrightarrow\) (b) \(\mathrm{Bi}(s)+\operatorname{excess} \mathrm{F}_{2}(g) \longrightarrow\) (c) \(\mathrm{Ca}_{3} \mathrm{As}_{2}(s)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow\)

Oxidation reactions are a type of chemical reaction where a substance loses electrons. This process either involves the addition of oxygen or the removal of hydrogen from a compound. For instance, in the reaction between arsenic and oxygen forming arsenic oxide, arsenic loses electrons to oxygen, resulting in its oxidation.

• Oxidation involves an increase in the oxidation state of the substance.
• The substance gaining electrons undergoes reduction.

In the oxidation of arsenic, the oxygen acts as the oxidizing agent because it accepts the electrons released by arsenic. Contrastingly, in a reduction reaction, a substance gains electrons and decreases its oxidation state. Understanding oxidation is crucial in balancing chemical equations like the ones provided in the exercise.

Stoichiometry is the area of chemistry that involves calculating the quantities of reactants and products in chemical reactions. It is based on the principle of the conservation of mass, meaning that the total mass of reactants in a chemical reaction equals the total mass of the products. When balancing chemical equations, such as the reactions in the exercise, stoichiometry helps ensure that the number of atoms for each element is equal on both sides of the equation.

• It helps predict the amounts of substances consumed and produced.
• Coefficients are used to balance the equations.

For example, in the equation for bismuth and fluorine, to balance it using stoichiometry, you adjust the coefficients of the reactants and products to ensure that there are equal numbers of each type of atom on both sides of the reaction.

Chemical reactions occur when substances interact to form new substances with different properties. They are often categorized by the type of reactants and products involved, and the type of change that occurs. The three reactions given in the exercise exemplify different kinds of chemical reactions: the formation of oxides and fluorides, and the reaction of a compound with water to produce hydroxides and gases.

• A chemical equation represents a chemical reaction.
• Reactants are the starting substances, and products are the substances formed.

For instance, in the calcium arsenide and water reaction, the reactants (calcium arsenide and water) react to form the products (calcium hydroxide and arsine gas), showcasing how chemical reactions lead to the formation of new compounds from the original substances.