Water Flashcards

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1
Q

Describe the structure of a water molecule

A

An oxygen atom covalently bonded to two hydrogen atoms, with a non linear shape.

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2
Q

What is the bond that links two water molecules together

A

A hydrogen bond

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3
Q

What is a hydrogen bond

A

A hydrogen bond is a weak interaction between the slightly negative oxygen of one water molecule and the slightly positive hydrogen of another.

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4
Q

Define the term polar

A

Opposite slight charges on two sides of a molecule, one slightly positive and one slightly negative

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5
Q

Explain why a water molecule is polar

A

Water is a polar molecule as the oxygen is more electronegative so attracts the shared pair of electrons more strongly than the hydrogen making the oxygen slightly negative and the hydrogen slightly positive

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6
Q

Define electronegativity and dipole

A
electronegativity = tendency for an atom to attract a bonding pair of electrons 
dipole = a molecule in which the concentration of positive charge is separated from a concentration of negative charge
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7
Q

list 5 roles water plays in life

A
transport medium 
solvent 
coolant 
reactant 
habitat
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8
Q

Explain how the polar nature of water allows it to be a transport medium, solvent, coolant, reactant and habitat

A

TRANSPORT MEDIUM - liquid over large range of temps, can dissolve many materials.
SOLVENT- dissolves polar and charged molecules as polar water molecule cluster around them, keeping them apart
COOLANT - high specific heat capacity - H bonds require a lot of energy to overcome
HABITAT - maintains constant temp as H bonds require a lot of energy to overcome

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9
Q

define hydrophilic and hydrophobic

A

hydrophilic - physical property of a molecule that is attracted to water
hydrophobic - physical property of a molecule that is repelled by water

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10
Q

define cohesion and adhesion

A

cohesion - water molecules attracted to other water molecules
adhesion - water molecules attracted to other substances

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11
Q

describe any other properties of water that makes it useful for life

A

transparent to light so plants under water can get light for photosynthesis and aquatic animals can see

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12
Q

examples of how water is used across the whole diversity of life

A

support - hydrostatic skeleton of earthworms and turgidity in plants
lubrication - synovial joints such as elbow have a sac of synovial fluid which stops bones rubbing against each other
buoyancy - wales couldn’t be as big
swimming - when something pushes against water there is an equal repelling force pulling forward
reactions - photosynthesis, hydrolysis reactions
high surface tension - organisms can suspend themselves on the surface - pond skaters
ice floats - so floats so organisms underneath can live
regulating reaction and conditions - sweating and high specific heat capacity

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13
Q

using the polar nature of water explain how it can dome above the level of the glass container, make the shape of a meniscus and capillary action

A

dome - cohesion between water molecules causes surface tension due to H bonds
meniscus - adhesion to sides of container draws water molecules up
capillary action - cohesion to water and adhesion to other molecules explains how water moves up narrow spaces - important in xylem

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