Water A1 Flashcards
(19 cards)
List the 5 key properties of water.
- It is a metabolite (e.g. in condensation and hydrolysis reactions). 2. An important solvent in reactions. 3. Has a high heat capacity, which buffers temperature. 4. Has a large latent heat of vaporisation, providing a cooling effect with loss of water through evaporation. 5. Has strong cohesion between water molecules; this supports water columns and provides surface tension.
What is the term given to describe the uneven distribution of electrical charges in water?
The term given to describe the uneven distribution of electrical charges in water is ‘dipolar’.
What structural feature of water makes it a good solvent?
The dipolar nature of water makes it a good solvent.
How do hydrogen bonds form in water molecules?
Hydrogen bonds form between different water molecules between the oxygen of one molecule and a hydrogen atom of another.
Describe the role of water as a metabolite.
Water is involved in many reactions, such as photosynthesis, hydrolysis, and condensation reactions. This is why it is essential that approximately 90% of the plasma in blood is water and the cytoplasm in cells is largely composed of water.
How does cohesion contribute to the movement of water in plants?
Due to water molecules sticking together, when water moves up the xylem in plants due to transpiration, it is as a continuous column of water. This is advantageous as it is easier to draw up a column rather than individual molecules.
Define hydrophilic molecules and give an example.
Hydrophilic are polar molecules that are attracted to water. An example of a hydrophilic substance is water itself.
What holds oxygen and hydrogen together within a water molecule?
Oxygen and hydrogen within a water molecule are held together by covalent bonds.
Describe the large latent heat of vaporisation in the context of water.
Large latent heat of vaporisation means that a lot of energy is required to convert water from its liquid state to a gaseous state. This is due to the hydrogen bonds between water molecules. This property provides a significant cooling effect for organisms, such as humans when they sweat.
Define a dipolar molecule.
A dipolar molecule is one that has an unevenly distributed charge. In the case of water, the oxygen atom is slightly negative, and the hydrogen atoms are slightly positive.
How does water’s large latent heat of vaporisation benefit organisms?
Water’s large latent heat of vaporisation provides a significant cooling effect for organisms. For example, when humans sweat, they release water onto their skin. The energy required to convert this water to a gaseous state cools the body.
Why is water considered a good solvent?
Water is a good solvent because many substances dissolve in it. Polar or charged molecules dissolve readily in water due to the fact that water is dipolar. The slight positive charge on hydrogen atoms will attract any negative solutes, and the slight negative charge on the oxygen atoms of water will attract any positive ions in solutes.
Describe the process by which heat energy is transferred from the skin to water during evaporation.
Large amounts of heat energy from the skin are transferred to the water to evaporate it, thereby removing a lot of heat and cooling the organism.
Which structural feature of water provides strong cohesion, a high latent heat of vaporisation, and a high specific heat capacity?
Hydrogen bonds between water molecules provide strong cohesion, a high latent heat of vaporisation, and a high specific heat capacity.
What is the effect of water’s large latent heat of vaporisation?
Water’s large latent heat of vaporisation provides a cooling effect with loss of water through evaporation. This is important for temperature regulation in living organisms.
How does cohesion provide surface tension to water and what is its significance?
Cohesion provides surface tension to water, enabling small invertebrates to move and live on the surface, providing them a habitat away from predators within water.
Explain the significance of water’s high heat capacity.
Water’s high heat capacity allows it to buffer temperature. This means it can absorb or release a large amount of heat without significantly changing its own temperature.
Explain the concept of high specific heat capacity in relation to water.
High specific heat capacity means that 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. This property helps organisms maintain a relatively stable internal temperature.
What does it mean for a molecule to be hydrophobic and provide an example.
Hydrophobic molecules are non-polar molecules that are repelled by water. An example of a hydrophobic substance is lipids.
