Chapter 2.4

Question 1

Water is the most abundant liquid on Earth. It has unusual properties due to? its dipolar nature and the subsequent hydrogen bonding that this allows.

Answer 1

its dipolar nature and the hydrogen bonding that this allows.

Question 2

Is water a covalent substance and why?

Answer 2

Water is a covalent substance as the hydrogen and oxygen share electrons in the outer energy level.

Question 3

Why is water polar?

Answer 3

Due to a disproportional distributing of the electron cloud density in the molecule, the oxygen is highly electronegative in comparison to the hydrogen. This makes the oxygen become slightly negative and the two hydrogen atoms become slightly positive so the molecule is polar.

Question 4

What causes hydroges bonding?

Answer 4

Due to the delta positive hydrogen and delta negative oxygen in a water molecule due to a disproportional distributing of the electron cloud density in the molecule, the oxygen is highly electronegative in comparison to the hydrogen. This makes the oxygen become slightly negative and the two hydrogen atoms become slightly positive this will cause water molecules to be attracted to each other, which is known as cohesion. As the delta positive hydrogen in one water molecule is attracted to the delta negative oxygen in another water molecule they will start to become attracted to each other this attraction between delta positive hydrogen and delta negative oxygen forms a bond between the delta positive h and delta negative oxygen this bond is called a hydrogen bond.

Question 5

1. Is a hydrogen bond weaker than a covalent bond?
2. What is a hydrogen bond?
3. How is water molecules connected together in a liquid?

Answer 5

1. The hydrogen bond is weaker than a covalent bond that links the oxygen and hydrogen inside the molecule but the hydrogen bond is stronger than most intermolecular forces, that connects molecule together. The hydrogen bond, is one of the strongest of the intermolecular forces, but compared to a covalent bond its weak.
   2.A hydrogen bond is a weak interaction that occurs between a slightly negative charged atom and a slightly s slightly positive charged atom.
   Each of the individual hydrogen bonds is quite weak but water forms lots if these hydrogen bonds worth lots of its neighbouring water molecule meaning so overall it forms a nice strong connection and this is how water connects together as a liquid, collectively, hydrogen
   3.Hydrogen bonds connects water molecules together in a liquid.

Question 6

Are hydrogen bonds collectively weak or strong?

Answer 6

Collectively, hydrogen bonds are strong, but are weak on their own.

Question 7

1. Water molecules had a specific heat capacity due to?

2. Why does water molecules have such a high boiling point?

Answer 7

1.The water molecules sticking together cohesion,due to hydorgen bonding. Therefore due to the cohesion due to the hydogen bonding it takes more heat energy to separate these molecules than if they did not bond to one another, because these forces of attraction(hydrogen bonding have to be overcome. 2.Due to the delta positive hydgen and delta negative oxygen this forms a hydrogen bond between the two water molecules. This hydrogen bond causes the water molecules to want t stick together which is know as cohesion. Therefore it takes more heat energy t sperate the two water molecules. The this is why water has a higher boiling point (100 degrees Celsius) compared to ethanol hi (70 degrees Celsius), for example.

Question 8

What property gives water the ability to be a buffer in living organisms

Answer 8

Due to water having a high heat capacity (this means it takes a lot of energy in the form of heat to separate water molecules from each other, due to hydrogen bonding) this means it can act as a buffer, this means it doesn’t change temperature quickly so can hold its temperature quite well. So therefore it doesn’t change state easily and get warmed up easily due to the water molecules wanting to stick together cohesion due to the hydrogenforen bonds between the water molecules.

Question 9

Why is it good that water acts as a buffer in our body?

Answer 9

To make sure our body temperature will not quickly rise and keep it at our body temperature 37 degrees Celsius. This doesn’t happen as water molecules act as a buffer inside our body so it takes a lots of energy to heat a given mass of water, so helps to keep the body temperature-stable at 37 degrees Celsius.

Question 10

Why is it vital that the body keeps its temperature at 37 degrees Celsius?

Answer 10

It is vital the body keeps at this temperature for enzyme-controlled chemical reactions. If the body temperature gets too high the active sites will denature and the reactants will not be able to turn into products. However, if the body temperature gets too low, the rate of enzyme and reactant collisions will drop, reducing the rate of reaction.

Question 11

What is latent heat of vaporisation?

Answer 11

Latent heat of evapouraisation is the amount of energy needed to heat one gram of water. Due to hydrogen bonds this give water a high latent heat of vaporisation. So lots of energy is required to evaporate 1 gram of water, due to the hydrogen bonding. Evaporation of water such as sweating in mammals is therefore a very effective means of cooling because body heat is used to evaporate the water, which This negative feedback efficiently decreases body temperature.

Question 12

How does sweat cool mammals down?

Answer 12

Evaporation of water such as sweating in mammals is therefore a very effective means of cooling because body heat is used to evaporate the water, which This negative feedback efficiently decreases body temperature.CHECK

Question 13

1. What is cohesion? water molecules have a tendency of sticking together. This is known as cohesion. When molecules meet air, for example at the top of a pond, due to intermolecular forces, they are resistant to leave the mass of water. A single water molecule may be pulled downwards and either side by 3 other water molecules, but nothing is pulling up out of the water mass (it is more strongly attracted to the water mass than it is to the air). This causes the molecules to be more closely packed at the surface of the water than in the water body and creates water tension which is strong enough to support small organisms such as pond skaters which are denser than the water itself.

Answer 13

1.Water molecules have a tendency of sticking together due to hydrogen bonding.

Question 14

What is surface tension?

Answer 14

Due to the cohesion between water molecules due to the hydrogen bonding whater molecules are attracted to each other. Therefore when water molecules meet the air, for example at the top of a pond, due to intermolecular forces, hyforgen bondsthey are pulled back into the bpdy of the water and thereofre ae restanct to lave until heat energy makes the bond break then water molecule will be ble to lave th body of the water, eveaporation. A single water molecule may be pulled downwards and either side by 3 other water molecules. This tension of being pullled back

Question 15

What causes surface tension? T

Answer 15

Due to hydrogen bonding water molecules have a tendency of sticking together. This is known as cohesion. When molecules meet air, for example at the top of a pond, due to intermolecular forces, they are resistant to leave the mass of water. A single water molecule may be pulled downwards and either side by 3 other water molecules, but nothing is pulling up out of the water mass (it is more strongly attracted to the water mass than it is to the air). This causes the molecules to be more closely packed at the surface of the water than in the water body and creates water tension which is strong enough to support small organisms such as pond skaters which are denser than the water itself.

Question 16

What is adhesion?

Answer 16

Adhesion is water molecules sticking to other molecules. It causes capillary action which is defined as the spontaneous flow of a liquid into a narrow tube or porous material. This movement does not require the force of gravity to occur. Adhesion can cause capillary action because it sticks the side of teh conatiners. In fact, it often acts in opposition to gravity, for example, when water climbs up the sides of a test tube to create a meniscus.

Question 17

How does water travel up the xylem?

Answer 17

Capillary action is how water travels up the xylem in the stem of plants and is dispersed to the leaves. Furthermore, it has enables once small plants to evolve into very tall plants because water is able to reach good heights (there is also other mechanisms for making the water rise up the plant).

Question 18

How does capillary action allow trees to evolve to grow very tall?.

Answer 18

Furthermore, it has enables once small plants to evolve into very tall plants because water is able to reach good heights (there is also other mechanisms for making the water rise up the plant), due to adhesion which is due hydrogen bonding which enables capillary action.

Question 19

1. Is water required in metabolism?
2. How is water used in metabolism?
3. Where in digestion are condensation reactions used? 4.Where is water used in there obviously more?
4. Where do most of the reactions take place in the cell?

Answer 19

1. Yes Water is also required in metabolism (metabolism is all the chemical reactions of life).
2. Water is used metabolism to break down many complex molecules by hydrolysis, for example, in the digestive system many polymers (such as starch) and dimmers (such as maltose) need to be broken down into smaller molecules. This allows the body to get all the nutrients it needs to be healthy.
3. The opposite to hydrolysis is a condensation reaction. This is where a molecule of water is produced as a biproduct of a reaction, from joining molecules together, for example, when amino acids join together to make proteins. This is needed in the body for growth and making enzymes.
4. The water is used in a hydrolysis reaction and for photosynthesis (if the organism is a plant).
5. Most chemical reactions take place in the cytoplasm of the cell, the cytoplasm is an aqueous medium which is 70-90% water. The fluid mosaic plasma membrane using the properties of water (being polar) to form a phospholipid bilayer, with a hydrophobic and hydrophilic end of the phospholipids in the membrane. Either side of the cell membrane, water is present, which is why a bilayer is formed.

Question 20

What is the difference between adhesion and cohesion?

Answer 20

Cohesion is when water molecules stick to other water molecules and adhesion is when water molecules stick to other thing

Question 21

1. Does water act as a solvent?

2. How does water acting as a solvent help the cells?

Answer 21

1.Yes another key function of water is to act as a solvent where other polar molecules such as salts, sugars and amino acids readily dissolved into it due to its dipolar qualities.
2.Water acting as a solvent allows water to be used for the transportation of such substances (notably in the bloodstream of animals and the xylem and phloem vessels found in plants). Water can be used in this way to transport many other substances: nutrients, urea, ammonia and hormones.
It also allows ATP (a source of immediate energy) and enzymes to diffuse to where they are needed in the cytoplasm of the cell.
Also, inorganic ions and small hydrophilic molecules such as amino acids, monosaccharides and ATP dissolve in water.

Question 22

1. Water is also transparent how does this help aquatic plants?
2. How does the water evaporating off our skin help organism?
3. As water is not easily compressed how does it help animals and plants?

Answer 22

1. Water is transparent which allows so aquatic plants to photosynthesise as light rays can penetrate the clear water.
   - It’s transparency also allows light to penetrate the jelly-like fluid in the eyeball allowing light to reach the retina and form an image.
2. Its evaporation cools organism and allows them to control their temperature
3. It is not easily compressed and therefore provides supports, for example the hydrostatic skeleton of animals such as the earthworm and turgor pressure in herbaceous plants.

Question 23

1.Where are inorganic ions found in organisms? Inorganic ions are found in organisms where they occur in solution in the cytoplasm of the cell and in body fluids and as well as part of larger molecules.
2. Are inorganic ions in very high concentrations or low concetarions in organisms?
They may be in concentrations that range from very high to very low.
3.What is ions job in the cell?
4. What is phosphates job in the cell?
5.What is hydrogen ions role
6.What is one of sodium ions job in the cell?
7.What are some of the tests for pure water?

Answer 23

1. Inorganic ions are found in organisms where they occur in solution in the cytoplasm of the cell and in body fluids and as well as part of larger molecules.
2. They may be in concentrations that range from very high to very low.
3. Inorganic ions perform a range of functions. the specific function a particular ion performs is related to its properties. For example, irons ions are found in haemoglobin where they play a role in the transport of oxygen.
4. phosphate ion that form a structural role in DNA molecules and a role in storing energy in ATP molecules.
5. Hydrogen ions are important in determining the Ph of solutions and therefore the functioning of enzymes. 6.In 5.In chapter 4.5 it talks about sodium ions being important in the transport of glucose and amino acids across plasma membrane
6. If it boils at 100 degrees and if it freezes at 0degrees, if there are any other particles in the water it do that