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What do you think are some useful characteristics of water? How do you think water helps the body function?. HOMEWORK. In 5 sentences, Explain why water is so important in biology. (Hint: explain using the properties of water). Chemistry of Water. A. Water’s Polarity.
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What do you think are some useful characteristics of water? How do you think water helps the body function?
HOMEWORK • In 5 sentences, Explain why water is so important in biology. (Hint: explain using the properties of water)
A. Water’sPolarity 1. Water molecules form by COVALENT BONDS between two hydrogen (H) atoms and one oxygen (O) atom.
a. Water molecules are POLAR - one side of the molecule is positively charged, while the other is negative.
b. Opposite charges are attracted to each other. - HYDROGEN BONDS form between H of one water molecule and O of another.
High Specific Heat • Water has a high specific heat because of Hydrogen bonds** • Specific Heat: How much heat energy it takes to raise the temperature by 1 degree.
B. PropertiesofWater 1. HYDROGEN BONDS allow water to have some unique properties. a. COHESION – water molecules HYDROGEN BOND to other water molecules.
- COHESION creates SURFACE TENSION, or solid-like behavior on the surface of water. Ex: Something light can “sit” on the surface of water.
b. ADHESION – water molecules hydrogen bond to molecules of other surfaces. Ex: Water drops remain in an “empty” water bottle.
CAPILLARY ACTION • The ability of a liquid to flow through narrow spaces without being affected by gravity or other natural forces. • Combination of adhesion and cohesion help this happen.
C. MixtureswithWater 1. MIXTURE - combination of two or more substances where each substance retains its individual properties.
a. HOMOGENEOUS MIXTURES are evenly distributed throughout. They are also known as SOLUTIONS.
-In a SOLUTION, the SOLVENTis the liquid into which something is dissolved. -The SOLUTEis what is being dissolved in the SOLVENT.
b. If something dissolves in water, it is SOLUBLE. -Only other POLAR substances dissolve in water.
3. Water is known as the “universal SOLVENT” because it will dissolve many SOLUTES. a. This is due to water’s POLARITY.
b. ACIDS - substances that release H+ when dissolved in water. -More H+ = more ACIDIC.
c. BASES - substances that release hydroxide ions (OH−) when dissolved in water. -More OH- = more BASIC.
4. Amount of H+ or OH- ions in a solution determines the strength of an ACID or BASE a. The amount of of H+ in a solution is called pH.
5. Metabolic processes require a neutral pH (6.5-7.5). a. BUFFERS - mixtures that balance the pH of an substance. -Ex: BUFFERS in our blood keep the pH at 7.4.