A: Two ends of the molecule have opposite charges.
Q: What is Cohesion?
A: Hydrogen bonding keeps water molecules close to each other, and this cohesion helps pull water upward in the microscopic water-conducting cells of plants.
Q: What is the different between Acids and Bases?
A: An acid is a substance that increases the hydrogen ion concentration of a solution; a substance that reduces the hydrogen ion concentration of a solution is called a base.
1. Most cells are surrounded by water, and cells themselves are about 70-95% water.
2. Water molecules stay close to each other as a result of hydrogen bonding.
3. Water has a high specific heat.
4. Ice floats because it has less dense than liquid water
5. The high specific heat of water relative to other materials, water will change its temperature less when it absorbs or loses a given amount of heat.
Figure 3.9
the pH scale and
pH values of some aqueous solutions.
When the pH scale is 7 it means Neutral H+ = OH-;When H+ > OH- it means Acidic and when H+ <>
Water molecule is the most common in living cells as most cells are 70-95% water. Water sticks to water because the polarity of water results in hydrgen bonding and water also sticks to other molecules because of the same reason. Therefore, it also has a high surface tension. Water expands when it freezes because the distance between water molecules increases from the liquid to the solid form.
Key terms
Cohesion: they hydrogen bonds hold the substance together, a phenomenon called cohesion.
Adhesion: the clinging of one substance to another called adhesion. Surface tension: it is related to cohesion, a measure of how difficult it is to stretch or break the surface of a liquid.
Specific heat: the specific heat is defined as the amount of heat that must be absorbed or lost for 1g of that substance to change its temperature by 1C.
Hydrophobic: having an aversion to water; tending to coalesce and form droplets in water.
Hydrophilic: having an affinity for water. S
olution: a liquid that is a homogeneous mixture of two or more substances.
Solute: a substance that is dissolved in a solution.
Aqueous solution: a solution in which water is the solvent.
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