3.1.7 Water Flashcards
In a water molecule, there are 2…atoms and 1… atom
Hydrogen
Oxygen
In a water molecule, there are 2…atoms and 1… atom
Hydrogen
Oxygen
In a water molecule the hydrogen atoms have a slight …. charge
Positive
In a water molecule the oxygen atom has a slight … charge
Negative
In a water molecule the covalent bonds between the hydrogen and oxygen atoms are described as being p…
Polar
In a water molecule the….are polar
Covalent bonds between the oxygen and hydrogen atoms
In a water molecule the hydrogen atoms have a slight positive charge and the oxygen atom has a slight negative charge because…
An oxygen atom has 8 protons but a hydrogen atom only has 1 proton
So the shared electrons are slightly pulled towards the positive protons in the oxygen
The forces of attraction between different water molecules are called…
Hydrogen bonds
(As the slightly positively charged hydrogen atoms from one water molecule are attracted to the slightly negatively charged oxygen atom of another water molecule and vice versa)
Hydrogen bonds refer to…
The forces of attraction between different water molecules
True or false, individual hydrogen bonds (forces of attraction between different water molecules) are strong
False
Each hydrogen bond is weak but because there are so many of them overall they are strong
7 key properties of water
Cohesion
Solvent
Transparent
Metabolite
High specific heat capacity
High latent heat of vaporisation
Ice floats on top of water (as ice is less dense than water)
Cohesion is where water molecules stick together due to…
Hydrogen bonds
Cohesion is where water molecules….due to hydrogen bonds
Stick together
….is where water molecules stick together due to hydrogen bonds
Cohesion
The biological significance of cohesion as a property of water is that…
It supports continuous columns of water in the xylem
It provides surface tension to support small insects on the surface of the water
The biological significance of transparency as a property of water is that…
It allows light to penetrate through so aquatic plants can photosynthesise
The biological significance of ice floating on top of water (ice is less dense than water) as a property of water is that
Lakes freeze from the top down maintaining aquatic life beneath
The biological significance of high specific heat capacity as a property of water is that…
Water buffers changes in temperature making aquatic environments more hospitable
The biological significance of metabolite as a property of water is that…
Water plays a role in chemical reactions e.g hydrolysis reactions and condensation reactions
The biological significance of metabolite as a property of water is that…
Water plays a role in chemical reactions e.g hydrolysis reactions and condensation reactions
The biological significance of solvent as a property of water is that…
Metabolic reactions can occur
Substances can be transported
The biological significance of high latent heat of vaporisation as a property of water is that…
Water provides a cooling effect through evaporation e.g sweating
There are no bonds between water and…which leads to surface tension
Air
Surface tension supports…..that live on the surface of the water so supports life and provides a habitat
Small insects e.g pondskaters
Adhesion is where water molecules stick to other ..
Polar molecules
(Different types of polar molecules stick to each other)
In the xylem, water molecules stick to the xylem walls which is known as …
Adhesion
(As the water molecules are sticking to other polar molecules)
Adhesion vs cohesion
Cohesion is where water molecules stick to each other due to hydrogen bonds
Adhesion is where water molecules stick to other polar molecules (e.g water molecules sticking to the walls of the xylem)
Water is a solvent which means that …. and…substances can dissolve in it
Polar
Ionic
Ions can be dissolved in water in the… of cells in order to be transported
Cytoplasm
(As water is a solvent)
At the top of a miniscus …occurs as the water molecules stick to the walls
Adhesion
Oil doesn’t dissolve in water because….
It isn’t polar or ionic
(Only polar or ionic substances can dissolve in water)
A condensation reaction is a chemical reaction where…
A water molecule is released when chemical bonds are formed between molecules
In a condensation reaction is water released or needed
Released
In a hydrolysis reaction is water released or needed
Needed
A hydrolysis reaction is a chemical reaction where…
A water molecule is needed to break up a large molecule into smaller molecules
In a condensation reaction a water molecule is released when…
Chemical bonds are formed between molecules
In a hydrolysis reaction, a water molecule is needed to..
Break up a large molecule into smaller molecules
Hydrolysis and condensation reactions are both examples of water as a m…
Metabolite
Condensation vs hydrolysis reactions
Condensation= water molecule released (when bonds are FORMED between molecules)
Hydrolysis= water molecule needed (to BREAK up a large molecule into smaller molecules)
Ice is…dense than water
Less
(So ice floats on water)
Ice floats on water because it is… dense than water
Less
True or false, as water freezes it expands
True
As water freezes it expands because…
Water molecules are held further apart by hydrogen bonds
(So it becomes less dense)
The biological significance of ice floating on water as a property of water is that lakes freeze top down maintaining….
Aquatic life beneath
Ice floats on water so when the top part of the lake freezes it….the water beneath so that it remains unfrozen (which maintains the aquatic life beneath)
Insulates
………is the property of water where water evaporates from a liquid to a gas and the process requires lots of energy in order to break the hydrogen bonds between the water molecules (this process carries energy away from the organism very quickly to cool them down)
High latent heat of vaporisation
During sweating, energy (in the form of heat) is carried away from the organism very….
Quickly.
(This has a cooling effect)
Evaporation requires lots of energy because….
The hydrogen bonds between water molecules need to be broken
High… means that lots of energy is needed for liquid water to turn into a gas (this means that energy can be carried away from the organism very quickly which then acts as a cooling effect)
Latent heat of vaporisation
2 thermal properties of water
High latent heat of vaporisation
High specific heat capacity
Thermal property of water that involves a change of state
High latent heat of vaporisation (lots of energy needed to turn water from a liquid to a gas so energy is carried away from the organism very quickly which acts as a cooling effect)
Thermal property of water that refers to liquid water only and doesn’t involve a change of state
High specific heat capacity
Thermal property which means water is thermostable and a thermal buffer
High specific heat capacity
High specific heat capacity means that lots of energy is needed to…
Raise temperature of 1kg of water by 1 degree
Water is a thermal buffer (as a result of having a high specific heat capacity) which means that it resists changes to…
Temperature
Water is a thermal buffer (as a result of having a high specific heat capacity) which means that it resists changes to…
Temperature
High latent heat of vaporisation vs high specific heat capacity
High latent heat of vaporisation means lots of energy is needed to change state of water from liquid to gas- this means energy is carried away from the organism very quickly so the evaporation provides a cooling effect
High specific heat capacity means lots of energy is needed to raise temperature of 1kg of water by 1 degree so water acts as a thermal buffer (resists changes in temperature)- this makes aquatic environments more hospitable (better to live in)
The biological significance of…means that water provides a cooling effect through evaporation e.g sweating
High latent heat of vaporisation
The biological significance of…means that water buffers changes in temperature making an aquatic environment more hospitable
High specific heat capacity
Water molecules are described as being polar because…
There is an uneven distribution of charge (the oxygen atom is slightly negative and the hydrogen atoms are slightly positive)
(The covalent bonds within the water molecule are also described as being polar)
Water molecules are described as being…because there is an uneven distribution of charge (the hydrogen atoms have a slight positive charge and the oxygen atom has a slight negative charge)
Polar
