Physical Changes In Liquids

When oxygen and hydrogen atoms are bonded together in water, the oxygen atom attracts the shared electrons more strongly than the hydrogen atoms. This creates an uneven distribution of charge, with the oxygen atom having a slightly negative charge and the hydrogen atoms having a slightly positive charge. Therefore, the correct answer is "positive charge." This charge distribution allows water molecules to form hydrogen bonds with each other, giving water its unique properties.

Water molecules are composed of two hydrogen atoms and one oxygen atom. The oxygen atom has a slightly negative charge, while the hydrogen atoms have a slightly positive charge. This creates a polarity in the water molecule, making it a polar molecule. The positive end of one water molecule (hydrogen) is attracted to the negative end of another water molecule (oxygen), and vice versa. This attraction between the opposite charges is called hydrogen bonding and is responsible for many of the unique properties of water, such as its high boiling point and surface tension.

One reason water and alcohol look differently on a surface is due to surface tension. Surface tension is the force that causes the molecules at the surface of a liquid to be pulled inward, creating a "skin" on the surface. Water has a higher surface tension compared to alcohol, which causes water to form droplets and beads on a surface, while alcohol spreads out more evenly. This difference in surface tension is why water and alcohol have different appearances on a surface.

Surface tension is a property of liquids, such as water, where the molecules at the surface are attracted to each other more strongly than to the molecules in the bulk of the liquid. This creates a "skin" or a cohesive force at the surface, which allows certain insects to walk on water and causes water droplets to form spherical shapes. The word "skin" accurately describes this cohesive force at the surface of the liquid.

Cellulose or wood is made of molecules held together by a covalent bond. Covalent bonds occur when atoms share electrons, resulting in a strong bond between the atoms. In the case of cellulose or wood, the molecules are made up of carbon, hydrogen, and oxygen atoms, which form covalent bonds to create a strong and stable structure. This type of bond allows cellulose or wood to have its characteristic strength and stability.

The way the liquids mix is based on the interaction between water molecules and the molecules that make up each liquid. This interaction determines how well the molecules of the liquids can mix with each other and with water. If the interaction is strong, the liquids will mix easily and form a homogeneous solution. If the interaction is weak, the liquids may not mix well and separate into layers.

When a liquid dissolves, its physical properties can change. This is because when a substance dissolves in a liquid, it becomes a homogeneous mixture, where the particles of the solute are evenly distributed throughout the solvent. This can result in changes in properties such as density, viscosity, boiling point, and conductivity. Therefore, it is possible for the physical properties of a liquid to change when it dissolves.

Water molecules on the surface are attracted downward because they have no water molecules above them. This is due to the cohesive forces between water molecules, which cause them to be more strongly attracted to each other than to the air molecules above. As a result, the surface molecules experience a net inward force, causing them to be pulled downward.

Wax paper is made by coating paper with a thin layer of wax, usually paraffin wax. The wax used in wax paper is composed of carbon atoms bonded to hydrogen atoms. This bonding between carbon and hydrogen atoms gives the wax its characteristic properties, such as being water-resistant and non-stick.

The question asks for three physical properties of liquids. Color, density, and surface tension are all physical properties that can be used to describe liquids. Color refers to the visual appearance of a liquid, density is the mass per unit volume of a liquid, and surface tension is the measure of how difficult it is to break or stretch the surface of a liquid. Chemical reactivity, on the other hand, is a chemical property and not a physical property.

The correct answer is mineral oil, vinegar, and alcohol because all three of these liquids are clear in appearance. Cola, on the other hand, is not a clear liquid as it has a dark color. Therefore, cola is not included in the list of clear liquids.

Both alcohol and water are known to be able to absorb into paper due to their molecular properties. Paper is a porous material, and both alcohol and water molecules are small enough to penetrate the tiny spaces within the paper fibers. This absorption can cause the paper to become damp or even disintegrate over time. Therefore, it is true that alcohol and water can absorb into paper.

Water and alcohol have different surface tension properties. Surface tension is the force that causes the molecules on the surface of a liquid to be pulled inward, creating a "skin" or "film" on the surface. In the case of water, its surface tension is stronger compared to alcohol. This means that water molecules are more strongly attracted to each other, causing them to form droplets on the wax paper instead of spreading out. On the other hand, alcohol has weaker surface tension, allowing it to be absorbed by the wax paper instead of forming droplets.

When a liquid is placed on a surface, its behavior can vary depending on the surface tension of the liquid and the surface energy of the material. In this case, water has a higher surface tension compared to alcohol, causing it to bead up on the plastic surface. On the other hand, alcohol has a lower surface tension, allowing it to spread out on the plastic surface. Therefore, the statement "On plastic, water beads up, alcohol spreads out" is true.

Mixing a substance with water is indeed one way to determine its identity. When a substance dissolves or mixes well with water, it suggests that the substance is likely a liquid or a soluble solid. This characteristic can be used to identify certain substances or confirm their properties. Therefore, the statement "One way to determine what a substance is, is to mix it with water and to see how it mixes" is true.

Both alcohol and water have oxygen atoms, and in both molecules, the oxygen atom carries a slight negative charge. This is because oxygen is more electronegative than hydrogen, causing the oxygen atom to pull the shared electrons towards itself, creating a partial negative charge. This similarity in the slight negative charge on the oxygen atom is what makes the statement "oxygen has a slight negative charge" the correct answer.