cassie bee
Jan 5
Explain how impurities are added to a pure substance lower its freezing point and increas its boiling point?
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Jan 5
Impurities are added to a pure substance to lower its freezing point and increase its boiling point through a process called colligative properties.
When impurities are added to a pure substance, they disrupt the regular arrangement of particles in the substance. This disruption makes it more difficult for the particles to come together and form a solid during freezing or escape from the liquid during boiling. As a result, the freezing point of the substance is lowered and the boiling point is increased.
The reason behind this phenomenon lies in the concept of vapor pressure and boiling point elevation. When a pure substance is heated, its particles gain energy and some of them escape from the liquid phase to the gas phase, creating vapor pressure. However, when impurities are present, they occupy space in the liquid and reduce the number of available sites for the particles to escape. This leads to a decrease in the vapor pressure, which in turn increases the boiling point of the substance.
Similarly, when a pure substance is cooled, its particles lose energy and start to arrange themselves in a regular pattern to form a solid. However, the presence of impurities disrupts this process by interfering with the formation of the solid lattice structure. As a result, the particles require more energy to overcome the impurities and form a solid, leading to a decrease in the freezing point of the substance.
Overall, the addition of impurities to a pure substance affects the intermolecular forces and the arrangement of particles, resulting in a lower freezing point and higher boiling point due to the disruption of the normal phase transitions.
When impurities are added to a pure substance, they disrupt the regular arrangement of particles in the substance. This disruption makes it more difficult for the particles to come together and form a solid during freezing or escape from the liquid during boiling. As a result, the freezing point of the substance is lowered and the boiling point is increased.
The reason behind this phenomenon lies in the concept of vapor pressure and boiling point elevation. When a pure substance is heated, its particles gain energy and some of them escape from the liquid phase to the gas phase, creating vapor pressure. However, when impurities are present, they occupy space in the liquid and reduce the number of available sites for the particles to escape. This leads to a decrease in the vapor pressure, which in turn increases the boiling point of the substance.
Similarly, when a pure substance is cooled, its particles lose energy and start to arrange themselves in a regular pattern to form a solid. However, the presence of impurities disrupts this process by interfering with the formation of the solid lattice structure. As a result, the particles require more energy to overcome the impurities and form a solid, leading to a decrease in the freezing point of the substance.
Overall, the addition of impurities to a pure substance affects the intermolecular forces and the arrangement of particles, resulting in a lower freezing point and higher boiling point due to the disruption of the normal phase transitions.
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