Chapter3
Questions
1) How did water go up to leaves in the tree?
Water from the roots reaches the leaves through a network of water-conducting cells. As water evaporates from a leaf, hydrogen bonds cause water molecules leaving the veins to tug on molecules farther down, and the upward pull is transmitted through the water-conducting cells all the way to the roots. The hydrogen bonds hold the substance together, a phenomenon called Cohesion.
2) The difference between hydrophilic and hydrophobic substances
The simple way to tell hydrophilic and hydrophobic is to see if the substance will dissolve in the water or not. Hydrophilic substance dissolves in the water, and hydrophobic substance doesn’t. However, there’re some substance can be hydrophilic without dissolving in water, such as colloid. Colloid molecule is too big to dissolve, so it will just remain suspended in the aqueous liquid of the cell.
3) What are the bonds of water molecules?
They are covalent bonds and hydrogen bonds. Inside the water molecule, they use covalent bonds to connect oxygen and hydrogen, but between water molecules, they use hydrogen bonds to link to each other.
Factors
1) Water molecules are shaped something like a wide V, with its two hydrogen atoms joined to the oxygen atom by single covalent bonds.
2) The hydrogen bonds hold the substance together, a phenomenon called Cohesion. The clinging of one substance to another is called Adhesion.
3) 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.
4) A liquid that is a completely homogeneous mixture of two or more substances is called a solution, the dissolving agent of a solution is the solvent, and the substance that is dissolved is the solute.
5) Heat is a form of energy
Summary:
They polarity of water molecules results in hydrogen bonding. The unequal distribution of electrons makes water a polar molecule, meaning that the two ends of the molecule have opposite charges. Four emergent properties of water contribute to earth’s fitness for life. They are cohesion and adhesion, high specific heat of water, solvent of life and fluidity. Acidic and basic conditions affect living organisms.
Questions
1) How did water go up to leaves in the tree?
Water from the roots reaches the leaves through a network of water-conducting cells. As water evaporates from a leaf, hydrogen bonds cause water molecules leaving the veins to tug on molecules farther down, and the upward pull is transmitted through the water-conducting cells all the way to the roots. The hydrogen bonds hold the substance together, a phenomenon called Cohesion.
2) The difference between hydrophilic and hydrophobic substances
The simple way to tell hydrophilic and hydrophobic is to see if the substance will dissolve in the water or not. Hydrophilic substance dissolves in the water, and hydrophobic substance doesn’t. However, there’re some substance can be hydrophilic without dissolving in water, such as colloid. Colloid molecule is too big to dissolve, so it will just remain suspended in the aqueous liquid of the cell.
3) What are the bonds of water molecules?
They are covalent bonds and hydrogen bonds. Inside the water molecule, they use covalent bonds to connect oxygen and hydrogen, but between water molecules, they use hydrogen bonds to link to each other.
Factors
1) Water molecules are shaped something like a wide V, with its two hydrogen atoms joined to the oxygen atom by single covalent bonds.
2) The hydrogen bonds hold the substance together, a phenomenon called Cohesion. The clinging of one substance to another is called Adhesion.
3) 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.
4) A liquid that is a completely homogeneous mixture of two or more substances is called a solution, the dissolving agent of a solution is the solvent, and the substance that is dissolved is the solute.
5) Heat is a form of energy
Summary:
They polarity of water molecules results in hydrogen bonding. The unequal distribution of electrons makes water a polar molecule, meaning that the two ends of the molecule have opposite charges. Four emergent properties of water contribute to earth’s fitness for life. They are cohesion and adhesion, high specific heat of water, solvent of life and fluidity. Acidic and basic conditions affect living organisms.
Diagram
From the diagram, we can see the water molecules are boned together by hydrogen bond and inside of the water molecules, the hydrogen atom bonded with oxygen atom by covalent bond. The charged regions of a polar water molecule are attracted to oppositely charged parts of neighboring molecules.
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.
Solution: 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.
video:http://www.youtube.com/watch?v=CT4pURpXkbY
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