Physical Properties - Online Tutor, Practice Problems & Exam Prep

Physical properties are measurable characteristics of a substance that can be observed without altering its chemical structure. Key examples include color, density, mass, volume, boiling point (bp), freezing point (fp), melting point (mp), and hardness. These properties allow us to describe and differentiate substances using our senses. Understanding these properties is essential for identifying materials and predicting their behavior in various chemical reactions.

Physical Properties Concept

So now we're going to take a look at the physical properties. We're going to say a physical property is a measurable property that describes the state of a chemical compound. Here, it can be observed through your senses without changing the chemical structure of a substance, so it's something that we can observe by either seeing it, touching it, smelling it, using our own faculties. Now, some of the most common types of physical properties, if we take a look at these images, in the first one we have a color palette. So for my fellow artists, we're going to say that color is a physical property, an object appears red, an object appears yellow. These colors that are shown to us represent physical properties. In the next image, we have a beaker filled with a liquid, which we can assume is water. One object sinks to the bottom of it while another one floats on top of it. Now, what determines if an object is heavy enough to sink into the liquid or light enough to float on top is its density. So, density is a physical property. Next, we have here an image of an anvil, which is related to the idea of mass. So, mass is a physical property. Next, we have a cube. The space inside the cube represents its volume. Next here, we have a pot which seems to be boiling or bubbling because the temperature has been raised. We'd say that physical properties here would be boiling points, but it wouldn't just stop at boiling point. We can also include freezing points and melting points. Now boiling points we can abbreviate as bp, freezing points as fp, and melting points as mp. Finally, if we take a look at this last image, we have a diamond. A diamond is known as one of the hardest natural materials in the universe. So, we're talking about a diamond being a representation of hardness. And also, besides hardness, we can talk about the opposite, the softness of a material. How easy is it for me to break that material versus how difficult it is? So, we're talking about a scale of hardness to softness when we talk about a material. These here represent the most common types of physical properties you'll come across. And just remember, if you can observe an object with your senses, then that can represent a physical property. Now that we've gone over the basic idea of it, let's move on to the next video and tackle some questions where we have to either identify what is or isn't a physical property.

Physical Properties Example

So if we take a look here at this example question, it says, which of the following represents a physical property? Now remember, a physical property is something we can observe through the use of our senses. Now, if we look at option A, it says potassium metal is extremely reactive when placed in water. We are talking about the reactivity of potassium within water. Reactivity is a chemical property. Next, rusting is a common issue with aluminum. We've talked about rusting before, we say that rusting is how the surface of a metal interacts with oxygen in the air. It undergoes a chemical reaction, and since we're talking about rusting as a type of chemical reaction, this could represent a chemical property. Neon has an unreactive nature; whether something is reactive, non-reactive, or unreactive, we're talking about its reactivity, so that is a chemical property. The butane in the lighter is highly flammable. Flammability is an example of a chemical property. The answer here has to be option E. Here it says mercury is a silvery liquid at 25 degrees Celsius. We're talking about its appearance, its color. Color is one of the first physical properties we discussed, so E would have to be my answer. A chemical property has more to do with an object and how it undergoes a chemical reaction.

Which of the following is not a physical property?

• A. The brittleness of solid sulfur.
• B. The density of iron is 7.87 g/cm³
• C. A platinum wire glows red when heated.
• D. smium is a silver-colored metal.
• E. An iron bar rusts.

Here’s what students ask on this topic:

What are physical properties in chemistry?

Physical properties in chemistry are measurable characteristics of a substance that can be observed without changing its chemical structure. These properties can be detected using our senses, such as sight, touch, and smell. Common examples include color, density, mass, volume, boiling point (bp), freezing point (fp), melting point (mp), and hardness. Understanding these properties helps in identifying materials and predicting their behavior in various chemical reactions.

How is density a physical property?

Density is a physical property because it describes the mass of a substance per unit volume without altering its chemical structure. It can be observed and measured directly. For example, if an object sinks in water, it has a higher density than water; if it floats, it has a lower density. The formula for density is:

$\rho =\frac{m}{V}$

where ρ is density, m is mass, and V is volume.

What is the difference between boiling point and melting point?

Boiling point (bp) and melting point (mp) are both physical properties, but they describe different phase changes. The boiling point is the temperature at which a substance changes from a liquid to a gas. The melting point is the temperature at which a substance changes from a solid to a liquid. Both properties are specific to each substance and can be used to identify and characterize materials.

Why is color considered a physical property?

Color is considered a physical property because it can be observed without changing the chemical structure of a substance. It is a characteristic that can be detected using our sense of sight. For example, the color of a substance can help identify it, such as the red color of iron oxide (rust) or the yellow color of sulfur.

How does hardness relate to physical properties?

Hardness is a physical property that measures a material's resistance to deformation, scratching, or abrasion. It can be observed and measured without altering the chemical structure of the substance. For example, diamonds are known for their high hardness, making them resistant to scratching. Hardness is often measured using the Mohs scale, which ranks materials based on their ability to scratch one another.