Biochemistry Flashcards
Describe the structure of water and how it influences polarity
The water molecule is shaped LIKE a V , like a distorted tetrahedral geometry. oxygen is more electrongegaitive than hydrogen, therefore pulls the electron density towards itself.
This unequal sharing makes it a polar molecule.
Describe the role of hydrogen bonding in water in respect with cohesion
at any given moment many of the molecules are linked by multiple hydrogen bonds. These linkages make water more structured than most other liquids. Collectively the hydrogen bonding hold the molecules together, called cohesion.
How does water strong cohesion play a role in the environment (tress, insects)
A result of cohesion is high surface tension, a measure of how difficult is it to break the surface of a liquid. The high surface tension of water, allows insects, spiders to walk on the surface.
Cohesion also contributes to the transport of water and dissolved nutrients against gravity in plants.
Describe the role of hydrogen bonding in water in respect with High heat capacity. What is high heat capacity?
High heat capacity is the specific heat of a substance that amount of heat is needed to be absorbed or lost for 1g of that substance to change its temperature by 1 degree
Describe the role of hydrogen bonding in water in respect with high heat capacity
The specific heat of water is 4.18 joules per gram. Water has a high heat capacity compared with other substances. Water’s high specific heat is attributable to hydrogen bonding. Heat must be absorbed in order to break hydrogen bonds and heat is released when hydrogen bonds form.
How does water high heat capacity impact the environment?
The high specific heat of water tends to stabilise ocean temperatures, creating a favourable environment for marine life. Additionally, organisms are primarily made of water, they are able to resist changes in their own temperature.
Describe the role of hydrogen bonding to boiling point
Water has a high heat of vaporisation relative to other liquids. To evaporate 1g of water at 25°C, about 580 cal of heat is needed- double the amount needed to vaporise a gram of alcohol or ammonia.
Describe the relative density of water and ice
Water is one of the few substances that are less dense as a solid than as a liquid. As a result, ice floats on liquid water, while other materials contract and become denser when they solidify water expands. Water reaches its greatest density at 4°C, many of the molecules are connected by hydrogen bonds only transiently. The hydrogen bonds are constantly breaking and re-forming.
Why is ice being less dense than water crucial for life
The ability of of ice to float due to its lower density is an important factor is the suitability of the environment for life. If ice sank, the ocean would freeze, making life impossible.
Draw NACL dissolving in water
Na attracted to oxygen, Cl attrcted to hydrogen
What is the ionisation of water
2H20 = H30+ = OH-
eqaul 10-7
What is an acid and a base
An acid increases the hydrogen ion, by losing protons
Base decreases hydrogen ion, by accepting hydrogen ions (protons) or forming hydroxide ion
What is a buffer
Buffer is a substance that minimises change in concentration of hydronium ions and hydroxide ions in a solution. Buffers contain weak acid and its conjugate base. Buffers allow biological fluids to maintain a constant pH
Describe which buffer maintains blood pH of 7.35-7.45
CO2+H20=H2CO3=HCO3- +h = CO32- + H
