Water Flashcards

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1
Q

What is the structure of a water molecule?

A
  • Water is a (di)- polar molecule.
  • Has unevenly distributed charge (due to oxygen atoms being slightly negative and hydrogen atoms being slightly positive.
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2
Q

Where are hydrogen bonds formed in water molecules?

A
  • Hydrogen bonds are formed between the slight negative oxygen atom (on one water molecule) and the slightly positive hydrogen atom (on another water molecule.)
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3
Q

What is meant by di- polar molecule?

A
  • Di- polar molecule has two different regions that are charged.
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4
Q

What is meant when we say water is a “metabolite?” Examples of reactions water is involved in?

A
  • This means that water is involved in chemical reactions (remember metabolism = sum of chemical reactions. )
  • Examples: photosynthesis, hydrolysis, condensation reactions.

() - extra info for clarification

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5
Q

Why is 90% of the plasma in the blood water and why is the cytoplasm mainly composed of water?

A
  • Because water is a metabolite (involved in chemical reactions. ) A good supply of water is necessary to be present in the body for the chemical reactions that occur in body (ie. hydrolysis/ condensation.)
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6
Q

What are the 5 key properties of water?

A

1.) It is a metabolite in many metabolic reactions.
2.) It is an important solvent in which metabolic reactions occur (metabolic reactions occur quicker in solution.)
3.) Has a high heat capacity, buffering changes in temp.
4.) Has a large latent heat of vapourisation - providing a cooling effect.
5.) Has strong cohesion between water molecules.

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7
Q

What do we mean when we say water is a good solvent? Why is water a good solvent (think in terms of its structure?)

A
  • Many polar (ie. charged) molecules dissolve easily in water due to fact it is dipolar.
  • Slight positive hydrogen will attract any negative ions in solutes.
  • Slight negative oxygen will attract any positive ions in solutes.
  • This will separate the solute/ dissociate the ions in the compound - and the solute will be dissolved.
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8
Q

What are polar molecules that can be dissolved in water often referred to as being?

A
  • Hydrophillic (attracted to water.)
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9
Q

What are non-polar molecules (that can’t dissolve in water) often referred to as?

A
  • Hydrophobic (repelled by water.)
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10
Q

Why is it useful in humans and plants for water to be a good solvent?

A
  • Means that essential polar molecules can be transported around the body easily in plasma/ blood (in humans.) to cells needed.
  • Plants –> sugars can dissolve in water in phloem/ mineral ions can dissolve in water in xylem - transporting polar molecules to required cells.
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11
Q

Why is it useful that water has a high specific heat capacity?

A
  • This means the temperature of water remains relatively stable, even if surrounding temp changes.
  • Internal temp of plants/ animals remain relatively constant despite outside temp (large amount of water in organisms.)
  • It also provides a stable temperature for aquatic organisms.
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12
Q

What do we mean when we say water has a high specific heat capacity? Why does water have a high SHC?

A
  • This means a lot of energy is required to raise the temperature of water.
  • This is because some of the heat energy is used to break the hydrogen bonds between water molecules (rather than increasing the temperature.)
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13
Q

Why is it important that the temperature of animals/ plants remains relatively constant?

A
  • Important so enzymes don’t denature (high temp) or reduce in activity (low temp) with temperature fluctuations.
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14
Q

What is meant when we say water has a large latent heat of vapourisation? Why does water have a large latent heat of vapourisation?

A
  • This means a lot of energy is required to convert water from a liquid state to a gaseo- Due to hydrogen bonds between molecules, a lot of energy is required to break the hydrogen bonds between water molecules/ convert the water into a gas.us state.
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15
Q

Why is it useful for humans that water has a large latent heat of vapourisation? Explain the example of sweating….

A
  • Provides a cooling effect.
  • Ie. humans sweat/ release water onto skin. Large amounts of heat energy can be transferred from the skin to the water (before the water evaporates.)
  • So, large amounts of heat energy are transferred to environment when the water evaporates but this occurred with little loss of water.
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16
Q

Why is it useful for plants to have a large latent heat of vapourisation?

A
  • A LARGE AMOUNT OF heat energy transferred to water in plant (before causing the water to evaporate.)
  • Through transpiration, the water evaporates , providing a cooling effect.
17
Q

What does it mean when we say water has “strong cohesion?”

A
  • This means that water molecules can stick together by hydrogen bonds.
18
Q

Why is water having strong cohesion useful for transport of water in the xylem?

A
  • The water molecules stick together.
  • Water moves up xylem (in transpiration stream) as a continous column of water (rather than individual water molecules as all the molecules are stuck together.)

() - extra info for clarification.

19
Q

What does water having strong cohesion produce where water meets air? What does this allow for?

A
  • Produces surface tension.
  • This allows invertebrates to live on surface of water (providing them a habitat away from any predators in the water itself.)