Classification Of Matter 6

Iron is a chemical element, which means it cannot be broken down into simpler substances by ordinary chemical means. It is represented by the symbol Fe on the periodic table. Iron is a pure substance composed of only iron atoms, making it an element. It is known for its strength and is widely used in construction, manufacturing, and various other industries.

When vinegar (an acid) reacts with baking soda (a base), a chemical reaction occurs. This reaction produces carbon dioxide gas, which is a completely different substance than the vinegar and baking soda. Since the reactants are transformed into a new substance with different properties, this is considered a chemical change.

Gasoline burning in the presence of oxygen is a chemical change because it involves a chemical reaction. During combustion, the molecules of gasoline and oxygen rearrange their atoms to form new substances, such as carbon dioxide and water vapor. This process releases energy in the form of heat and light. Therefore, the change from gasoline to carbon dioxide and water vapor is a chemical reaction, indicating that it is a chemical change.

Gold is a chemical element with the symbol Au and atomic number 79. It is a dense, soft, malleable, and ductile metal that is known for its bright yellow color. As an element, gold cannot be broken down into simpler substances by chemical means. It exists as pure gold and is not combined with any other elements or compounds. Therefore, the correct answer is "element."

Mercury is an element because it is a pure substance that cannot be broken down into simpler substances by chemical means. It is represented by the symbol Hg on the periodic table and is a heavy, silvery metal that is liquid at room temperature. Mercury exists as individual atoms and does not combine with other elements to form compounds or mix with other substances to form mixtures.

The formation of a layer of oxide on the outside of the metal is a chemical change because it involves a chemical reaction between the iron and oxygen in the air. This reaction results in the formation of iron oxide, which is a different substance with different properties than the original iron. Therefore, the change is not just a rearrangement of particles, but a transformation of the iron into a new compound.

Nitrogen is an example of an element because it is a pure substance that cannot be broken down into simpler substances by chemical means. It consists of only one type of atom, nitrogen atoms, and is found on the periodic table as the element with the symbol N.

Carbon dioxide is a compound because it is made up of two different elements, carbon and oxygen, chemically bonded together. In a compound, the elements are combined in a fixed ratio and can only be separated through a chemical reaction. Carbon dioxide is formed when carbon atoms bond with oxygen atoms, creating a stable molecule with specific properties. Therefore, it fits the definition of a compound rather than an element or a mixture.

A vegetable soup is considered a heterogeneous mixture because it contains different components that are not uniformly distributed throughout the mixture. In vegetable soup, you can find various ingredients like vegetables, herbs, spices, and sometimes even meat or broth. These components can be easily distinguished and separated from each other, making the soup a heterogeneous mixture.

Burning wood involves a chemical reaction known as combustion, where the wood reacts with oxygen in the air to produce heat, light, and various gases like carbon dioxide and water vapor. This process results in a permanent change in the composition and properties of the wood, making it a chemical change. Physical changes, on the other hand, do not alter the chemical makeup of a substance. Magical change is not a scientifically recognized concept, hence it is not a valid option.

Coffee is considered a homogeneous mixture because it is composed of multiple substances that are uniformly distributed throughout. When coffee is brewed, the water, coffee grounds, and any added ingredients such as sugar or milk all mix together to form a consistent and uniform solution. This means that no matter where you sample from within the coffee, you will find the same composition and properties. Therefore, coffee can be classified as a homogeneous mixture.

A heterogeneous mixture is a combination of different substances that are visibly distinguishable. In the case of raisin oatmeal, it is made up of various components such as oats, raisins, and possibly other ingredients like sugar or cinnamon. These components can be seen and differentiated within the mixture, indicating that it is a heterogeneous mixture.

Calcium chloride is a compound because it is composed of two or more elements chemically bonded together. In this case, calcium and chlorine combine to form calcium chloride. Compounds have a fixed composition, properties different from their constituent elements, and can only be separated by chemical means.

Table salt, sodium chloride, is a compound. A compound is a substance that is made up of two or more different elements chemically combined in a fixed ratio. Sodium chloride is composed of sodium (Na) and chlorine (Cl) atoms that are bonded together in a specific ratio of one sodium atom to one chlorine atom. Therefore, it is considered a compound rather than an element or a mixture.

The boiling of water at 100 degrees Celsius is a physical change. This is because the change in state from liquid to gas does not alter the chemical composition of water. The molecules of water remain the same, only the arrangement and energy level of the molecules change. Therefore, it is considered a physical change rather than a chemical change.

When water is separated into hydrogen and oxygen by electrolysis, a chemical reaction occurs. Electrolysis involves passing an electric current through water, causing the water molecules to break down into their constituent elements, hydrogen and oxygen. This process involves the rearrangement of atoms and the formation of new substances, which is characteristic of a chemical change.

When sugar dissolves into water, it undergoes a physical change. This is because the sugar molecules are dispersed throughout the water, forming a homogeneous mixture. No new substances are formed, and the chemical composition of both sugar and water remains the same. The process of dissolving involves breaking the intermolecular forces between sugar molecules and allowing them to mix with the water molecules, resulting in a solution. Therefore, it is considered a physical change rather than a chemical change.

Tap water is considered a mixture because it contains various substances, such as minerals, gases, and impurities, dissolved or suspended in it. These components can vary in composition and concentration, making tap water a heterogeneous mixture. Additionally, tap water can also contain additives like chlorine for disinfection purposes, further supporting the idea that it is a mixture rather than a compound or an element.

Pure water is a compound. A compound is a substance made up of two or more different elements chemically combined in a fixed ratio. In the case of water, it is composed of two hydrogen atoms bonded to one oxygen atom, forming the chemical formula H2O. This chemical combination creates a new substance with different properties than its individual elements. Therefore, pure water is considered a compound rather than an element or a mixture.

The ocean is considered a heterogeneous mixture because it is composed of various substances that are not evenly distributed throughout. It contains a combination of different salts, minerals, gases, and organic matter, which can vary in concentration and composition depending on location and depth. This diversity in the ocean's composition makes it a heterogeneous mixture rather than a homogeneous one, where the components would be uniformly distributed.