The three most common states of matter are solids, liquids, and gases. The addition of energy can affect the particle-level behavior of each state. And at certain temperatures, a sample of matter can transition from one state to another state.
States of Matter - Questions 10 Help
This help page addresses all questions in the third actiity titled Heating Curves. There are eight questions in this activity. Each question involves the analysis of a heating curve (temperature-time plot for the heating of a sample of matter). Here is one of the questions.
Version 1:
A substance is placed in a closed vessel. The substance is continuously heated and its temperature monitored, leading to the heating curvebelow. Five regions of the heating curve are labeled with a number.
During which numbered region of the graph is there ...
... only solid present?
... only liquid present?
... only gas present?
Solids, liquids, and gases are the three most common states of matter. A sample of matter typically exists in one of these three states. Yet heating, cooling, and/or changes in pressure can cause the sample to change from one state to another state. A heating curve is a graphical depiction of how a sample of matter changes over time as heat is added to it. The curve consists of a series of diagonal and horizontal sections as shown below.
Suppose that we start with a sample of material in a closed container at a temperature below its melting point. In other words, suppose we have a solid in a container that has a lid on it. And suppose we begin heating the material. The addition of energy (through heating) to the solid will increase the kinetic energy of its particles. But because solid state materials consist of particles that are in a locked position, the only response that the particles can have is to vibrate with a greater energy. And so the solid particles begin vibrating more and more vigorously while remaining in their fixed location within the ordered structure of the sample. This vibration continues with greater and greater intensity as the heating continues. The temperature of the sample increases since temperature is a measure of the amount of vibrational movement (in solids) of the particles. This describes the diagonal line labeled 1 on the above heating curve.
Once the temperature reaches the melting point, the addition of energy through heating has a different effect. At the melting point, the vibrations have become so intense that the particles begin to force their way out of the structured arrangement typical of the solid state. The added energy is used to cause the change from a solid to a liquid state. As more and more energy is added via heating, there is a co-existence between solid and liquid states as the added energy is simply used to cause the transition. This describes the horizontal line labeled 2 on the above heating curve.
Once melting has completed, the sample is then in the liquid state. Particles can vibrate like they did in the solid state, but mainly they can also move about the bulk of the sample by sliding past one another. There are still enough intermolecular forces to prevent them from filling the entire container; the liquid remains as a condensed state. As energy is continuously added to the sample, the kinetic energy of the particles increases. That is, the particles move faster and vibrate more vigorously. This greater movement is reflected by the increase in temperature of the sample as the liquid warms up towards its boiling point. This describes the diagonal line labeled 3 on the above heating curve.
Once the temperature reaches the boiling point, the addition of heat once more effects the sample in a different manner. At the boiling point, the particle speed becomes so fast that the particles can escape the intermolecular forces that hold them in the condensed liquid state and the sample begins to vaporize. It is during this time that the addition of energy through heating causes the sample to undergo a change of state. Both liquid and gas are present in the container as more and more of the liquid undergoes vaporization. This describes the horizontal line labeled 4 on the above heating curve.
Once the last drop of liquid has changed to gas, the sample fills the entire volume of the container. Continued heating causes particles to move faster and faster. This increased speed is reflected by an increase in temperature. This describes the diagonal line labeled 5 on the above heating curve.
Once the temperature reaches the melting point, the addition of energy through heating has a different effect. At the melting point, the vibrations have become so intense that the particles begin to force their way out of the structured arrangement typical of the solid state. The added energy is used to cause the change from a solid to a liquid state. As more and more energy is added via heating, there is a co-existence between solid and liquid states as the added energy is simply used to cause the transition. This describes the horizontal line labeled 2 on the above heating curve.
Once melting has completed, the sample is then in the liquid state. Particles can vibrate like they did in the solid state, but mainly they can also move about the bulk of the sample by sliding past one another. There are still enough intermolecular forces to prevent them from filling the entire container; the liquid remains as a condensed state. As energy is continuously added to the sample, the kinetic energy of the particles increases. That is, the particles move faster and vibrate more vigorously. This greater movement is reflected by the increase in temperature of the sample as the liquid warms up towards its boiling point. This describes the diagonal line labeled 3 on the above heating curve.
Once the temperature reaches the boiling point, the addition of heat once more effects the sample in a different manner. At the boiling point, the particle speed becomes so fast that the particles can escape the intermolecular forces that hold them in the condensed liquid state and the sample begins to vaporize. It is during this time that the addition of energy through heating causes the sample to undergo a change of state. Both liquid and gas are present in the container as more and more of the liquid undergoes vaporization. This describes the horizontal line labeled 4 on the above heating curve.
Once the last drop of liquid has changed to gas, the sample fills the entire volume of the container. Continued heating causes particles to move faster and faster. This increased speed is reflected by an increase in temperature. This describes the diagonal line labeled 5 on the above heating curve.