Chemical Reactions Quiz

A chemical reaction where two or more reactants combine to form a single product. It can be represented by the general formula A + B → AB, where A and B are reactants and AB is the product. Examples include the formation of water from hydrogen and oxygen, or the synthesis of sodium chloride from sodium and chlorine.

A chemical reaction where a single reactant breaks down into two or more products. It can be represented by the general formula AB → A + B, where AB is the reactant and A and B are the products. Examples include the decomposition of hydrogen peroxide into water and oxygen, or the breakdown of calcium carbonate into calcium oxide and carbon dioxide.

A chemical reaction where a substance reacts with oxygen, producing heat and light. It involves the rapid oxidation of a fuel, usually a hydrocarbon, in the presence of oxygen. Examples include the burning of wood, natural gas, or gasoline.

A reaction where a more reactive element displaces a less reactive element from a compound. It can be represented by the general formula A + BC → AC + B, where A is the more reactive element and B is the less reactive element. An example is the reaction of zinc with copper sulfate, where zinc displaces copper from the sulfate.

A chemical reaction where the positive and negative ions of two reactants switch places to form two new products. It can be represented by the general formula AB + CD → AD + CB, where AB and CD are the reactants and AD and CB are the products. An example is the reaction of silver nitrate with sodium chloride, where silver and sodium ions switch places to form silver chloride and sodium nitrate.

Indicators are substances that change color in the presence of an acid or a base. They are used to determine the pH of a solution.

Acids are substances that release hydrogen ions (H+) when dissolved in water. Acids have a pH of 0-6.9.

Bases are substances that release hydroxide ions (OH-) when dissolved in water. Bases have a pH of 7.1-14.

Neutralization is a chemical reaction between an acid and a base. The products are salt and water.

The pH scale measures the acidity or alkalinity of a solution. A lower pH indicates a stronger acid, while a higher pH indicates a stronger base. A pH of 7 is neutral.

A change in a substance where a new substance is formed. For example; burning wood, rusting metal or making a cake.

A change in a substance where the chemical composition remains the same. For example; melting ice, boiling water, dissolving sugar in water.

A property of a substance that can be observed without changing the composition of the substance. For example: color, density, melting point, boiling point, odor, hardness, and state.

A property of a substance that describes how it reacts or changes when it interacts with other substances. For example: flammability, reactivity, ability to rust, ability to burn, oxidation, and corrosion.

A test used to identify a substance by its unique reaction with a reagent. For example; a glowing match test for oxygen, cobalt chloride paper for water vapor.

Elements in Group IA of the periodic table, such as lithium (Li), sodium (Na), and potassium (K), are known as alkali metals. They are highly reactive metals with one valence electron, making them eager to lose it and form a +1 cation.

Elements in Group IIA of the periodic table, such as beryllium (Be), magnesium (Mg), and calcium (Ca), are classified as alkaline earth metals. They are moderately reactive metals with two valence electrons, and tend to lose them to form +2 cations.

Elements in Group VIIA of the periodic table, such as fluorine (F), chlorine (Cl), and bromine (Br), are collectively called halogens. They are highly reactive nonmetals with seven valence electrons and a strong tendency to gain one electron to form -1 anions.

These elements are found in Group VIIIA of the periodic table and include Helium (He), Neon (Ne), Argon (Ar) and others. These gases are very unreactive because of the presence of a full outer shell of electrons, making them stable and less likely to form bonds.

When two or more atoms, ions, or molecules have the same number of electrons, they are called isoelectronic species. For example, the arsenic ion ($As^{3-}$) has the same number of electrons as the noble gas krypton (Kr).

When a metal and a nonmetal react, they form an ionic compound. The metal atom loses electrons to become a positively charged ion (cation), while the nonmetal atom gains electrons to become a negatively charged ion (anion). The oppositely charged ions attract and form a compound. For example, beryllium (Be) is a metal, and fluorine (F) is a nonmetal, and they react to form the ionic compound beryllium fluoride (BeF₂).

A covalent compound is formed when two or more nonmetal atoms share electrons to achieve stability. For example, carbon dioxide (CO₂) is a covalent compound where carbon shares electrons with two oxygen atoms. The chemical formula for a covalent compound represents the number of each atom in the molecule, using prefixes like 'di' for two, 'tri' for three, etc.

Elements that exist naturally as diatomic molecules, meaning two atoms are bonded together. These include hydrogen (H₂), nitrogen (N₂), oxygen (O₂), fluorine (F₂), chlorine (Cl₂), bromine (Br₂), and iodine (I₂).