1 / 22

Water and Solutions 2.2

Water and Solutions 2.2. Water and Living Things. Water and Solutions 2.2. Water in Living Things All living things have a percentage of water in their makeup The human body contains about 72%, or two thirds, of it’s makeup in water. Water and Solutions 2.2. Water in Living Things

mohawk
Télécharger la présentation

Water and Solutions 2.2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Water and Solutions 2.2 Water and Living Things

  2. Water and Solutions 2.2 Water in Living Things • All living things have a percentage of water in their makeup • The human body contains about 72%, or two thirds, of it’s makeup in water.

  3. Water and Solutions 2.2 Water in Living Things • Cellsin the body are in large part made up of water. • Waterhelps move nutrients and other substances in and out of your cells.

  4. Storage of Energy • Water absorbs heat more slowly and retains this energy longer than many other substances. • Many organism release excess heat through water evaporation. • Humans cool themselves by sweating. • The water vapor lost through evaporation of sweat carries away heat from the body.

  5. Storage of Energy • In organisms, this ability to control temperature enables cells to maintain a constant internal temperature when the external temperatures are varying drastically. • This is called homeostasis and is how organisms help regulate their body temperature.

  6. Cohesion and Adhesion • The hydrogen bonds between water molecules cause the cohesion of liquid water. • Cohesion is an attraction between substances of the same kind.

  7. Cohesion and Adhesion • Because of cohesion, water and other liquids form thin films and drops. • Molecules at the surface of the water link together by hydrogen bonds like a crowd of people linked holding hands.

  8. Cohesion and Adhesion • This attraction between water molecules causes a condition know as surface tension • Surface tension prevents the surface of water from stretching or breaking easily.

  9. Cohesion and Adhesion • Water molecules are also attracted to many other “similarly polarized” substances. • Adhesion is an attraction between different substances.

  10. Cohesion and Adhesion • Adhesionpowers a process called capillary action in which water molecules move upward through the stem of a plant. • The attraction of water to the walls of the tube sucks the water up more strongly than gravity pulls it down.

  11. Cohesion and Adhesion • Water moves upward through a plant from roots to leaves through a combination of capillary action, cohesion and other factors. • Putting a paper towel into water is a good demonstration of capillary action as the paper towel draws the water up.

  12. Aqueous Solutions • Many substances dissolve in water. • For example, when you add salt to water, the resulting mixture is a saltwater solution. • A solution is a mixture in which one or more substances are evenly distributed in another substance. • When you drop food coloring into water and it changes the color, you have created a solution.

  13. Acids and Bases • While the bonds in water molecules are strong, at any time a certain amount of these bonds will break, forming a hydrogen ion (H+) and a hydroxide ion (OH-). Water molecule

  14. Acids and Bases • Hydrogen ions (H+) are ions with a positive charge and make water acidic. • We say that acidic water with a positive charge has a positive polarity. Water molecule

  15. Acids and Bases • Hydroxide ions (H-) are ions that have a negative charge and make water more base. • We say that water with a negative charge has a negative polarity. Water molecule

  16. Acids and Bases • As a result, pure water always has a low amount of hydrogen ions and hydroxide ions in equal numbers =

  17. Acids and Bases • Compounds that form hydrogen ions (H+) when dissolved in water are called acids. • When an acid is added to water, the concentration of hydrogen ions (H+)in the solution is increased above that of pure water. (greater than 7.0pH)

  18. Acids and Bases • In contrast, compounds that reduce the concentration of hydrogen ions in a solution are called bases. (OH-) • Many bases lower the concentration of hydrogen ions because hydroxide ions react with hydrogen ions to form water molecules.

  19. Acids and Bases • A pH scaleis based upon the concentration of hydrogen ions in a solution. • Pure water is balanced at a pH of 7.0 and is neutral pH.

  20. Acids and Bases • The more hydrogen ions (+), the more acidic the solution. • An acidic solution has a pH lower than 7.0 • Lemon juice or vinegar are both very acidic.

  21. Acids and Bases • The more hydroxide ions a solution has, the less acidic and more base the solution. • A base solution has a pH reading higher than 7.0 (neutral) and is considered more alkaline. • Lye is a compound that is very alkaline.

More Related