A1.1 Water SL - PDF

A1.1 WATER Learning goals I can name and explain the physical properties of water that makes it essencial for life. o Hydrogen bonds o Buoyancy, viscosity, thermal conductivity and specific heat capacity I can name and explain the chemical properties of water that makes it es...

A1.1 WATER Learning goals I can name and explain the physical properties of water that makes it essencial for life. o Hydrogen bonds o Buoyancy, viscosity, thermal conductivity and specific heat capacity I can name and explain the chemical properties of water that makes it essencial for life. o Cohesive, adhesive and solvent properties I can name the challenges and opportunities of water A1.1.1 Water as the medium for life Approximately 71% of our planet’s surface is water, with 97% found in oceans and only 3% as fresh Water has existed on Earth for 3.8 billion years The first cells originated in water (the molecular ingredients of life need a solvent – water – to react with each A1.1.2 Hydrogen bonds as a consequence of the polar covalent bonds within water molecules Covalent bond: a bond between atoms in which pairs of electrons are shared. Polar molecule: Hydrogen bond: because the oxygen a weak attractive atom has more intermolecular protons, it attracts force; the shared electrons a hydrogen atom in more thus creating an a unequal distribution molecule is of charge.. attracted to an electronegative DRAW ! Represent two or more water molecules and hydrogen bonds between them. Delta (δ) symbols indicate a small charge. Indicate the hydrogen bonds and the covalent bonds A1.1.3 Cohesion of water molecules due to hydrogen bonding and consequences for organisms demo Surface tension Cohesion is the force by which individual molecules of the same type attract and associate (stick together) Water molecules stick together because of hydrogen bonding  Another example of cohesion is then water is enable to be drawn up inside the xylem of a plant stem in a  A1.1.4 Adhesion of water to materials that are polar or charged and impacts for organisms Adhesion is the force by which individual molecules cling to surrounding materials and surfaces Materials and substances with an affinity for water are described as hydrophilic BioFlix : Water Transport in Plant s: Transpiration-Cohesion- Tension Mechanism (pear soncmg.com) !!!! Cohesion (‘co’ means ‘together’) is attraction between water Capillary action in plants exper iment with paper towel - Scien molecules, while ce experiments for kids - YouTu Explore … What happens when we mix water with: - Sugar - salt - oil A1.1.5 Solvent properties of water linked to its role as a medium for metabolism and for transport in plants and animals Water is a liquid at the temperatures and pressure that exist over much of the Earth’s surface. As a result, we have a liquid medium with distinctive thermal and solvent properties.  Water as a solvent… Water being a polar molecule is a powerful solvent for polar substances such as ionic substances like sodium chloride, NaCl due to dissociation of its ions (Na+ and Cl−). Polar organic molecules (for example, amino acids have a negatively charged carboxyl group, –COO−, and a positively charged amino group, –NH3+) and sugars dissolve in  Water as a solvent… Substances dissolved in water are called solute and water is the solvent A charged or polar substance that interacts with and dissolves in water is said to be hydrophilic: hydro means "water," and philic means "loving." In contrast, nonpolar molecules like oils and fats do not interact well with water. They separate from it rather than dissolve in it and are called hydrophobic: phobic means "fearing."  Water’s solvent properties allow it to be used as a medium for metabolism Most enzymes catalyse reactions in aqueous solution. Enzymes require a certain level of water in their structures to maintain enzyme shape and stability, enabling them to function effectively. Hydrophilic molecules such as dissolved salts, fatty acids, sugars, amino acids and Time to work… Go to OneNote Go to folder Exercises Work with exercises #3 to #11 (just highlight the correct alternative) If you have time, upload the drawing of your water molecules  A1.1.6 Physical properties of water and the consequences for animals in aquatic habitats The physical properties of water depend on the hydrogen bonding between water molecules and include buoyancy, viscosity, thermal conductivity and specific heat capacity.  Buoyancy and thermal conductivity Buoyancy: the ability of any fluid to provide a vertical upwards force on an object placed in or on it Thermal conductivity (k): the measure of how easily heat flows through a specific type of material  Viscosity and specific heat capacity https://images.app.goo.gl/V9HuQmHvs29SELpx8 Viscosity: a measure of a fluid’s resistance to flow. A thick fluid is more viscous than a thin fluid. Below the surface, water molecules slide past each other very easily. This property is described as low viscosity. Specific heat capacity: the amount of energy required to raise the temperature of 1kg of a substance by 1°C Water has the highest specific heat capacity of any liquid, which makes it good for temperature regulation (it takes a lot of energy to raise the temperature Contrast the physical properties of water with those of air The importance buoyancy, viscosity, thermal conductivity and specific heat capacity in relation to life can be illustrated by looking at two animals that live in Arctic waters as well as in the air or on land, such as the black-throated loon (Gavia arctica) and the ringed seal (Pusa hispida)  can swim large distances underwater BIRDS in general … hollow bones to decrease weight air trapped between feathers to provide insulation buoyancy needs to be overcome to catch underwater prey species Buoyancy Viscosity has solid bones to increase its when it flies, the feathers move weight and to compress air through the air easily and with from its lungs and feathers to minimum friction decrease buoyancy and enable need to produce resistance against successful diving the water to achieve movement. It Black-throated loon (Gavia arctica) has webbed feet that provide a large surface area to push against water have a great deal of need to produce resistance subcutaneous fat (blubber) against the water to achieve that acts as a buoyancy aid movement. Uses its flippers and provide thermal (modified arms) to propel itself Ringed seal (Pusa  Thermal conductivity Specific heat capacity Its feathers has air trapped which The specific heat capacity of air forms an effective insulating layer is lower than water, so air between its skin and the outside temperature tends to fluctuate air. Feathers also restrict more. Therefore, aquatic convection currents by trapping a environments have relatively Black-throated loon (Gavia arctica) thin layer of air that is not able to more stable temperatures than move easily, which also helps to terrestrial (land) environments maintain the body temperature of the bird The ice forms a platform on relies on thick blubber to which seals can live. Ringed insulate its body seals have claws to dig through Layers of ice also have ice to produce holes so that they insulating properties because can emerge from their aquatic ice’s thermal conductivity is habitat to breathe Ringed seal (Pusa low Time to work… Go to OneNote Go to folder Exercises Work with exercises #18 to #24 (short answers) If you are not finished, consider the rest homework Learning goals I can name and explain the physical properties of water that makes it essencial for life. o Hydrogen bonds o Buoyancy, viscosity, thermal conductivity and specific heat capacity I can name and explain the chemical properties of water that makes it essencial for life. o Cohesive, adhesive and solvent properties I can name the challenges and opportunities of water