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Summary list for 2.2 Water
- Hydrogen bonds form between polar water molecules.
- This force give water special properties, e.g. cohesiveness, adhesiveness, thermal
and solvent properties. - Glucose, amino acids and salts are hydrophilic while cholesterol and fats are hydrophobic.
- Compare the thermal properties of water with those of methane and explain how this affects its use a as a coolant in sweat.
- Compare the solubility of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in water and link this to the way they are transported.
- Explain benefits of water properties to living organisms (Transparency and density not required).
- Evaluate how significant hydrogen bonding is in the properties of water
Mindmaps
These diagram summaries cover the main sections of topic 2.2 Water
Study them and draw your own list or concept map from memory.
Exam style question about hydrogen bonding
Understanding the way in which hydrogen bonding affects water molecules is an important skill from this topic.
Answer the question below on a piece of paper, then check your answer against the model answer below.
Outline the properties of water which result from hydrogen bonding between water molecules [4]
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Click the + icon to see a model answer.
This question expects students to be able to compare the properties of water with those of a similar sized molecule which has no hydrogen bonding. Essentially, hydrogen bonding changes all the properties because it increases the attraction between water molecules.
Water and methane are molecules with similar sizes, at least they are more similar to one another than either of these molecules is to Glucose.
Compare and contrast the properties of water and methane. [4]
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This is a self marking quiz containing questions covering the topic outlined above.
Try the questions to check your understanding.
START QUIZ!
The diagram below shows dotted lines between a group of water molecules.
What do these dotted lines represent?
Hydrogen bonds form between polar water molecules. Between the O and the H of an adjacent molecule.
Which properties of water molecules could be said to result from hydrogen bonding?
Hydrogen bonding gives water special properties, e.g. high cohesiveness, high adhesiveness, high specific heat capacity, and excellent solvent properties.
Transparency is a property of water, but it is not caused by hydrogen bonding.
Some medicines are designed to dissolve in a glass of water.
What is the term used to describe polar molecules which are easily soluble in water?
Glucose, amino acids and salts are hydrophilic while cholesterol and other fats are hydrophobic.
What is the difference between oxygen molecules (carried in red blood cells) and glucose molecules (carried in blood plasma) which can explain why they are transported in different ways in the blood?
Compare the high solubility of glucose, amino acids, and sodium chloride in water and link this to the way they are transported in blood. Oxygen is slightly soluble in water.
Compare the low solubility fats in water an link this to the fact they are not transported in blood very well.
Which property of water helps to keep lakes at relatively stable temperatures?
Explain benefits of water properties to living organisms (Transparency and density not required.)
Because water has a high specific heat capacity, it takes a lot of energy to make it change temperature, and this is what cools the skin in sweating.
The diagram below shows some molecules of water, methane and oxygen.
For what reason are the boiling points of methane and oxygen so much lower than the boiling point of water?
Hydrogen bonding is really important in the properties of water. By holding the water molecules together more strongly the hydrogen bonds cause water to have a higher m.p. and b.p than methane. C-H bonds in methane (CH4) are evenly arranged around the molecule so it is not polar so there is no hydrogen bonding in methane, and also in oxygen, the O-O bond is not polar.
Which of the following molecules are readily soluble in water?
Water has important solvent properties.
Polar molecules and ionic salts dissolve readily in water and this helps them to be transported in the blood.
Drag and drop activities
Test your ability to construct biological explanations using the drag and drop questions below.
Drag and drop learning engagements
Test your construction of biological knowledge using the drag and drop questions below.
Drag and drop the correct term into the gap to describe the importance of water properties to living systems.
raise carbohydrates Cohesion soil High sweat other heat capacity Solvent aquatic water stems hydrophilic
The polarity of the covalent bonds between the atoms in the water molecule causes hydrogen bonds between the molecules. These give the following properties which are vital to the functions of living organisms:
- , water molecules attract each other - allows an unbroken column to rise up the of tall trees.
- Adhesion, water molecules are attracted to charged molecules - retains water in .
- - dissolves molecules such as ions, proteins and in blood plasma.
- High , large quantity of heat needed to the temperature of water, stable environments.
- heat of vapourisation, large quantity of heat to evaporate - as a coolant.
Examiner hint - Use correct terminology. You need to know examples of how the properties of water are important to living systems.
energy solvent enzyme bilayers protective polar Amphoteric keratin Insoluble transported Lipids
The nature of the water molecule makes it a good for hydrophilic molecules. Water is the solvent in which most controlled reactions of the body occur and, in which, soluble substances are round the organism.
substances have important roles in storage and as structural components of cells and tissues. and starch are insoluble storage compounds, once formed inside a cell they cannot diffuse out of the cell. Insoluble proteins such as found in hair, horn and hooves have and locomotive functions.
phospholipids molecules assemble into forming the basis of the cell membrane.
Just for fun
Everyone needs a bit of fun while they revise. Try this Water wordshoot revision game. Can you reach the leader board?
How much of Water 2.2 have you understood?
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