Purity and Formation

• What should you be able to describe by the end of this video?

  Using melting and boiling point data
• What is a pure substance in chemistry?

  A substance not mixed with others
• Give an example of a pure element.

  Pure silicon
• Give an example of a pure compound.

  Pure sodium chloride
• What happens to the melting and boiling points of pure substances?

  They have specific fixed temperatures
• How do impure substances behave when heated?

  They melt and boil over a range of temperatures
• What does a fixed melting point indicate about a substance?

  It indicates the substance is pure
• How can you determine if water is pure using temperature measurements?

  By measuring its melting and boiling points
• What is a formulation in chemistry?

  A complex mixture designed as a useful product
• Why are the quantities of components in a formulation carefully measured?

  To ensure the product has desired properties
• What can you find plenty of questions about in the revision workbook?

  Pure and impure substances, formulations
• What does a graph of a pure substance's melting and boiling points look like?

  It shows fixed temperatures for melting and boiling
• What does a graph of an impure substance's melting and boiling points look like?

  It shows a range of temperatures for melting and boiling
• How does the melting point of a mixture differ from that of a pure substance?

  A mixture melts over a range of temperatures
• What is the melting point of pure water?

  0 degrees Celsius
• What is the boiling point of pure water?

  100 degrees Celsius
• What happens to the temperature of pure water when it melts?

  The temperature stops rising at 0 degrees Celsius
• What happens to the temperature of pure water when it boils?

  The temperature stops rising at 100 degrees Celsius
• How do scientists produce mixtures?

  By carefully measuring components in formulations
• What is the significance of the melting and boiling points in determining purity?

  They indicate whether a substance is pure
• What is the relationship between formulations and useful products?

  Formulations are designed to create useful products
• How does the presence of impurities affect the melting and boiling points of a substance?

  It causes them to vary instead of being fixed
• What are the two types of pure substances mentioned?

  Single elements and single compounds
• What is an example of a formulation?

  Examples were shown but not specified