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 materials, such as identifying a diamond's hardness or determining whether an object sinks or floats based on its density. Understanding these properties is essential for studying chemical compounds and their behaviors in various states of matter.

Physical Properties Concept

So now we're gonna take a look at the physical properties. Physical property itself 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 gonna 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. Now 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 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 on it. Here, we'd say that physical properties would be boiling point, but it wouldn't just stop at boiling point. We can also include here freezing point or melting point. Now boiling point we can abbreviate as bp, freezing point as fp, and melting point as mp. Finally, if we take a look at this last image, we have a diamond. So a diamond is known as one of the hardest natural materials in the universe. It's one of the hardest materials you can find in nature. So when we talk about a diamond, we're just talking about the hardness of an object. 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 let's 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 can be observed through the use of our senses. If we look at option a, it says potassium metal is extremely reactive when placed in water. We're talking about the reactivity of potassium within water. Reactivity is a chemical property. Next, rusting is a common issue with aluminum. We've discussed before 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 or 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. Therefore, 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. Remember, 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 and how are they different from chemical properties?

Physical properties are measurable characteristics of a substance that can be observed without changing its chemical structure. Examples include color, density, mass, volume, boiling point, freezing point, melting point, and hardness. These properties can be observed using our senses or measured with instruments. In contrast, chemical properties describe a substance's ability to undergo chemical changes, resulting in the formation of new substances. Examples of chemical properties include reactivity with acids, flammability, and oxidation states. The key difference is that physical properties can be observed without altering the substance's chemical identity, while chemical properties involve a change in the substance's chemical structure.

How does density determine whether an object sinks or floats in a liquid?

Density is defined as mass per unit volume and is a key physical property that determines whether an object will sink or float in a liquid. The density of an object is compared to the density of the liquid. If the object's density is greater than the liquid's density, the object will sink. Conversely, if the object's density is less than the liquid's density, the object will float. This principle is based on Archimedes' principle, which states that an object submerged in a fluid experiences a buoyant force equal to the weight of the fluid displaced by the object.

What is the significance of boiling point, freezing point, and melting point in identifying substances?

Boiling point (bp), freezing point (fp), and melting point (mp) are critical physical properties used to identify and characterize substances. The boiling point is the temperature at which a liquid turns into a gas, the freezing point is the temperature at which a liquid turns into a solid, and the melting point is the temperature at which a solid turns into a liquid. These points are unique for each substance and can be used to confirm the identity and purity of a material. For example, pure water has a boiling point of 100°C and a freezing point of 0°C at standard atmospheric pressure.

Why is hardness considered an important physical property?

Hardness is a measure of a material's resistance to deformation, scratching, or abrasion. It is an important physical property because it provides information about the durability and wear resistance of a material. For example, diamonds are known for their exceptional hardness, making them ideal for cutting tools and abrasives. Hardness is also used in material science and engineering to select appropriate materials for specific applications, ensuring that they can withstand mechanical stresses and maintain their structural integrity.

How can physical properties be used to differentiate between substances?

Physical properties such as color, density, mass, volume, boiling point, freezing point, melting point, and hardness can be used to differentiate between substances. By measuring and comparing these properties, scientists can identify and distinguish materials. For example, the density of gold is significantly higher than that of most other metals, allowing it to be easily identified. Similarly, the unique boiling and melting points of substances can help confirm their identity and purity. These properties provide a non-destructive means of analyzing and categorizing materials in various scientific and industrial applications.