Matter is described as anything that occupies space and has mass. The universe is composed of matter. Solids, liquids, and gases are three states of matter naturally found on earth.
Classes of Matter
Figure 1: The organization of matter
Depending on its composition, matter can be classified into several categories, as shown in figure 1, either as a mixture or pure substance.
Keep reading to know why this topic can be challenging for teachers and their students, five tactics to improve the situation, and learn the benefits of a virtual lab.
Let's discuss three reasons why matter and phase changes can prove to be tough, even for an academically sound student.
Since matter and phase changes occur at the molecular level, you can’t see or feel them. Not being able to see the processes and having few relevances to the real world can make studying it unappealing and make it hard for students to stay motivated.
Three states of matter exist on earth: solid, liquid, and gas. Water molecules move differently depending on their physical state. In the gaseous form, they move freely, in the liquid form, they have a more limited range of motion, and in the solid form, they do not change position but vibrate within a place.
Figure 2: Three states of a water molecule.
Solids have a definite shape and volume. The liquid takes the shape of its container; has a certain volume but does not have a certain shape. Gases, also known as vapors, take on the volume and shape of their container; it does not have a definite shape and volume. The arrangement of the molecules in a matter determines the different properties of solids, liquids, and gases.
Phase change: The state of matter depends on the intermolecular forces (IMF) and kinetic energy (KE) of the particles - be they molecules, ions, or atoms. The chemical identity of the particles in a liquid determines the nature and strength of the intermolecular attractions. To move from one state of matter to another, we need to add enough energy to overcome the intermolecular forces holding the particles together. The phase change from solid to gas is called sublimation, and from gas to solid deposition. A change from solid to liquid is known as melting, and from liquid to solid is known as freezing. From liquid to gas, this is called evaporation, and from gas to liquid condensation. The change from solid to liquid, solid to gas, and liquid to gas is an endothermic process, meaning energy must be added. The reversal process is an endothermic process, which means that energy is released from the substance
Figure 3: Phase change.
Melting: The energy required to break intermolecular forces and increase particle motion during a solid-liquid transition is called the heat of fusion or enthalpy of fusion (ΔHfus) while in evaporation, the speed of particle movement continues to increase with increasing temperature. The shift from liquid to gas is named evaporation. The energy involved in this phase change is called the heat of vaporization or enthalpy of vaporization (ΔHvap).
Sublimation: The energy required for sublimation is called the sublimation heat or the sublimation enthalpy (ΔHSub). In general, the heat of sublimation is much greater than the heat of vaporization, with the heat of fusion being the smallest. This is because all intermolecular forces are broken in the gaseous state, while in liquids, they are intact, and in solids, they are mostly intact. More energy is required to break all intermolecular forces between particles.
With those points in mind, here are five things you can incorporate into matter and phase change classes to make them more engaging, accessible, and fun for you and your students.
The Greek atomists were the first to think about the basic structure of matter. They thought, in astonishing insight, that if you could cut matter into smaller and smaller pieces, you would get its tiniest particles, which they called atoms. The word itself means that which cannot be cut. Furthermore, they regard atoms as eternal and indestructible, thus forming the essence of existence. However, when they are combined in various ways, they form everything we see in the world, from rocks to water droplets to frogs and humans. In this way, becoming captures the essence of nature, of existing things and changing things. They went further and, in an attempt to create a unified theory of nature, suggested that thoughts and feelings are also made of atoms. A unified theory is as old as philosophy.
Although the modern concept of the atom is very different from the pre-Socratic Greek concept, the idea that matter is made up of tiny indivisible particles remains alive and well and forms the basis of particle physics, the branch of physics that seeks to discover the basic components of matter.
The heat curve is a temperature graph versus the amount of heat input. The heating curve shows the change in temperature that occurs as a substance absorbs an increasing amount of heat. We can also observe that the temperature remains constant as long as a change in state occurs. The temperature is flat because all the heat energy is used to break the intermolecular forces.
Figure 4: The heating curve of water at a constant pressure of 1 atm. 1: Ice is heating towards the melting point; 2: The ice is melting. H2O(s) --> H2O(l); 5: The steam is heating to a certain temperature.
Latent heat of fusion The latent heat of fusion, or enthalpy of fusion (Δ_H_fus), is the amount of heat required to change 1 mole of a substance from solid to liquid. Latent heat of vaporization The latent heat of vaporization, or enthalpy of vaporization (Δ_H_vap), is the amount of heat required to convert one mole of a substance from a liquid state to a gaseous state. The enthalpy of sublimation can be calculated as the sum of the enthalpies of melting and evaporation.
Distillation is a powerful method for separating substances from homogeneous mixtures. Distillation technology uses the difference in boiling points. The reaction mixture is heated to the boiling point of the most volatile liquid. First, the most volatile substances evaporate in a stationary boiler, forming vapors. The vapor is then condensed back into a liquid after passing through the condenser and collected in the receiving flask at the end. This arrangement is called simple distillation. This works well for separating mixtures containing volatile components.
Figure 5: Distillation instrument 1. thermometer; 2. Distillation flask; 3. Heating mantle; 4. condenser; 5. Cooling water out; 6. cooling water in; 7. Collecting flasks.
The condenser, distillation flask, and thermometer are connected via an adapter (3-way adapter or Y arm). A mercury bulb thermometer is inserted into the hole leading to the condenser in this adapter, allowing the bulb to be surrounded by hot steam, which is essential for reliable temperature readings. It is possible to connect the vacuum source to the distillation apparatus to achieve vacuum distillation. Simple distillation cannot produce a pure substance if the mixture contains several volatile components. More complex distillation is required to obtain a pure substance from a mixture of different volatile components.
Figure 6: Overview of the Ethanol Distillation Process
The condenser is a part of the distillation apparatus. The upper part is connected to the distillation flask and thermometer via an adapter, the lower part is connected to the collection plate. Cold water continues to flow in the outer chamber, which cools the glass condenser. Water enters the condenser at the bottom and exits at the top. When the hot steam enters the interior of the condenser, it is cooled by the cold surface, condenses, and flows into the condenser into the collection flask. This setting prevents the hottest steam from touching the coldest water, avoiding heat shock to glassware.
Visualizing a topic as complex and abstract as matter and phase change makes all the difference. Physical and chemical changes that take place daily around us become obvious. A chemical change is when matter changes from one form to another. Some examples of chemical changes:
Rust Formation: Rust is a combination of iron, oxygen, and water that existed before rust was formed.
Nitroglycerin explosion: The gas produced is a completely different kind of substance from the original substance.
All kinds of combustion
Food is cooked or rotted.
A physical change is a change in the state of a substance but not in its composition. It occurs when matter transitions between solid, liquid, or gaseous states. You can see the physical changes when you freeze or boil water. Water changes state but still consists of water molecules. With a chemical or physical change, the total amount of matter does not change much. The phenomenon of change is called the law of conservation of matter.
Visualization can be very helpful in understanding this topic. There are few options other than memorization. The three states of matter can be remembered as SinGLe, where the lowercase letters are excluded, as shown:
S - Solid,
G - Gas and
L - Liquid.
A unique way to teach matter and phase change is through virtual laboratory simulations. At Labster, we are dedicated to providing fully interactive state-of-the-art lab simulations that use gamified elements such as storytelling and scoring systems in an immersive, 3D world.
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