GED Science Practice Test: Phase Changes in Matter
With an increase or decrease of energy in a system, a material in one state of matter can change to another state of matter. The following image shows the different phase changes. Going left to right, energy increases. Going right to left, energy decreases:
The different phase changes can be described as follows:
- Melting – The process by which a substance changes from its solid state to its liquid state.
- Freezing– The process by which a substance changes from its liquid state into its solid state.
- Evaporation – A process by which a substance changes from its liquid state to its gas state by random particle movement.
- Sublimation– The process by which a substance changes directly from its solid state to its gas state without becoming a liquid first.
- Boiling– A process by which a substance changes from its liquid state to its gas state.
- Condensation – The process by which a gas becomes a liquid.
- Deposition-The process by which a gas changes directly from its gaseous state to its solid state without becoming a liquid first.
The point at which a substance changes from one state to another is called a point, such as the melting point. The melting point of solid ice, for example is 32°F (or 0°C). The different points (melting point, boiling point, etc.) are also examples of intrinsic properties.
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Read the following passage and answer the question below:
Distillation is a method of separating mixtures based on differences in volatility of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction. Commercially, distillation has a number of applications. It is used to separate crude oil into more fractions for specific uses such as transport, power generation and heating. Water is distilled to remove impurities, such as salt from seawater. Air is distilled to separate its components—notably oxygen, nitrogen, and argon—for industrial use. Liquid chemicals for diverse uses are often distilled after synthesis to remove impurities and unreacted starting materials. Distillation of fermented solutions has been used since ancient times to produce distilled beverages with a higher alcohol content. The premises where distillation is carried out, especially distillation of alcohol, are known as a distillery. A still is the apparatus used for distillation.
As mentioned, distillation is used to produce beverages with a higher alcohol content. More specifically, this kind of distillation is called fractional distillation, becauses it separates water and alcohol based on their different boiling points. If alcohol has a boiling point of 78⁰C, and water has a boiling point of 100⁰C, which of the following events during distillation is most likely to contribute to higher alcohol content as a result of distillation?