Topic 1 Environment PDF

Topic 1: Environment Q. Jorge Rubén Ochoa Sanfelice Matter and Environment  What’s an environment in nature? On planet earth, a better definition The environment most basic would be: the sum of physical, definition is just a certain area...

Topic 1: Environment Q. Jorge Rubén Ochoa Sanfelice Matter and Environment  What’s an environment in nature? On planet earth, a better definition The environment most basic would be: the sum of physical, definition is just a certain area chemical, biological, social, which contains certain economical and cultural components elements, usually alive. which are correlated and affect each other. Positive impacts from humans We all belong to an ecosystem! How complex is an ecosystem?  In any environment there are physical, chemical and biological factors Abiotic factors Physical factors Chemical factors Biological Factors Biotic Factors The environment most basic definition is just a certain area which contains certain elements, usually alive. Let’s identify some biotic and abiotic factors How much does a human really need? The consequences of our actions To understand why we affect the environment and why we need to understand the matter concept  But what is matter? The textbook definition of matter is anything that has mass and takes up space…  What is energy? The textbook definition of energy is the capacity of doing work… They are correlated, but… that’s the job of physics people Transformations: mass - mass Any transformation requires or releases energy, but the Like the chemical industry objective is to make new compounds, not the energy.  Here, the transformation’s Transformations: mass - energy objective is just the release of energy from mass to do a task. Transformations: energy – energy Already produced energy to another source The moment we started doing transformations… we changed the history of the world A simple diagram could be:  Next topic: States of matter! How particles are arranged, aggregated When things are way too energetical or too hot, there is no order and no aggregation states. As thing cool down, things tend to order. More energy Water is the only compound in nature that is present in these three states! Less energy  Solid state: when particles only vibrate but don’t move Solid state is characterized for having a definite volume and shape. This is causes by the strong cohesion forces between molecules, not allowing them to move freely but just to vibrate. In other words, they are fixed. Liquid state: particles can move, but they are together nevertheless Liquid state is characterized for having a definite volume but not a shape. There are cohesion forces that keep them together, yet they are not that strong to keep them fixed. In other words, particles feel each other and are kept together, et they move freely, adapting to any recipient. Gaseous state: particles are as free as a bird Gaseous state is characterized for not having a definite volume nor a shape. The cohesion forces are too weak too keep particles together, they just move freely. In other words, they will just spread and spread, and spread. Summary of the most common states But… what happens when we heat up things more and more? Plasma is also called ionized gas, in other words, a gas that got so hot that it lost their electrons. It occurs at high temperatures (500 or more for some substances) Plasma the most common state of matter because stars are the most abundant space body And… what happens when we freeze things to the limit? Bose-Einstein condensate! Bose-Einstein condensate was first a theory and then proven right experimentally. When particles start to freeze more and more, Near 0 K or -273.15 °C instead of having a single solid, they start to accumulate in super small , wave behaving crystals, quantum crystals/ice, due to the small temperatures.  Further characteristics of gases Because the cohesion forces Combustion engine uses this If you compress a between the molecules are so characteristic to move up and gas a lot it will low, gases don’t mind changing down the piston which can be eventually become their volume at a great extend. used to do any mechanical a liquid They can be expanded or work… like moving a car! (liquefaction), pretty compressed at ease. useful to carry large quantities of gases  Further characteristics of gases The molecules are so free, that the distance between them are really big. Thus, the density of gases are way lower than those from liquids or solids. A good example is CO2 ! 0.002 g/mL 1.562 g/mL That’s almost a thousand times denser, just between phases! Further characteristics of gases Gases diffuse spontaneously and mix with all the other gases in a recipient. They also produce a pressure on the surroundings or walls of the container. More Changes of state: going from one energy phase to another Less energy But, how is that process going on? Why does the temperature keep constant? To change a phase, first you need to beat the cohesion forces. While doing so, the temperature remains the same but not how much energy you provide! When we give in energy, it’s called an endothermic process, when we get energy it’s called exothermic  Endothermic A change from lower to bigger energy is called ENDOTHERMIC, we need energy More energy Less energy Exothermic A change from higher to lower energy is called EXOTHERMIC, we get energy And how do we call them? The temperature at which a phase change occurs is called (the phase change) point. Example: Condensation point Remember? Abiotic factors Physical factors Chemical factors  What’s a property? What the hell is this guy talking A quality or trait about?? that’s specific to In the case of an object or matter/substances individual , that means that a property is something that defines it or describes it in a certain way Why are they useful?  Properties can be general or specific General: you Specific: you can cannot use it to sue it to differentiate defferentiate Mass is a general property, Boiling point is a everything considered specific property. matter has it. You can’t tell Water boils at 100 °C this two apart just for the and oil at 300-350 °C mass!  Properties can depend on the quantity (extensive) or keep constant (intensive) Extensive Intensive properties: mass, properties: density, volume. color, smell Density or color are intensive Mass is an extensive properties, because doesn’t property because it matter if it’s a cup or a lake, depends on how much water will still be transparent sugar you have and have a density of 1g/mL  Because Properties can be classified as wither how biological process are in the substance is by itself (physical) or by essence how it can transform (chemical) chemical, biological/me Chemical property: a dical Physical property: a characteristic of properties are characteristic of the transformation like how easy considered object itself like mass, a substance oxidizes, reacts, chemical, like flexibility, color. combusts, etc. toxicity. Changes: they happen all the time! We cannot perceive all the changes going around, so we need always a starting and end point  In the natural world, we can define two types of changes: Physical and Chemical changes Physical change: when the study object changes yet its composition stays the same, the substance is kept the same from A to B. The ball’s materials are kept the Your ligaments bend so your knee Ice melts… but same, its position changed and has mobility, but thanks god it it is still water! that’s it. doesn’t change its composition… Physical changes are reversible by other physical changes Because physical changes do not alter the substance composition, I can reverse it by other physical process.  Chemical changes: When the substance changes (remember mass-mass transformation) Chemical change: when a substance changes of identity. If you burn wood, it’s not wood anymore, it’s water and CO2 Lead and Iodine atoms Iron reacts slowly but steadily Coal (C) and oxygen rearrange, and they become an with oxygen in the presence of combust to CO2 and H2O, insoluble salt, with a different water. It’s not Fe anymore, it’s it’s a chemical reaction composition and color. FeO or Fe2O3. Chemical changes can be reversible by other chemical changes… or irreversible ☹  How to identify a chemical change from a physical change? The chemical change transforms the PHYSICAL properties When I bend the steel it When iron corrodes, all its keeps it properties: It’s still physical properties change: it’s bright, malleable, now a brittle dust, not bright conducts heat and but opaque brown, it doesn’t electricity. conduct electricity anymore, its density changed.  What’s the difference of a chemical change and a chemical property? Chemical property is how the wood A chemical change describes COULD change. Its flammable in something that already is or was other words is: “It can undergo a transformed: The combustion chemical reaction with oxygen to describes the already CHANGED burn” wood to CO2 and Water  What’s the difference of a chemical change and a chemical property? Chemical property is how the Chemical change is how the smoke cigarette COULD affect your body. affected your lungs' cells. The Its cancerogenic in other words is: smoke changed chemically your “It can harmfully change the respiratory system, and not in a chemical composition of your cells good way. and eventually provoke cancer” Classification of matter: is it pure or a mixture?  The general classification of matter is based at the molecular level. If it has only one type of particles it is pure, if it has two or more it’s a mixture. Pure substances: Only one type of atom/molecule. Matter can be, in weird cases, is made of just one kind of particle (pure). If it’s just ONE kind of atom, is called an element. If the particle is made from two or more different atoms it’s a compound. More than two substances: Mixture Mixtures can have the particles arranged in an indistinguishable way. A perfect mixture called homogeneous. If the particles are not arranged in a perfect way, all to the point we can see them, they are called heterogeneous.  A homogeneous mixture has, AT A MOLECULAR LEVEL, the same distribution of molecules. That’s why they seem the same and, in the case of solutions, they are transparent. Suspension: a heterogeneous mixture that if enough time passes, the phases will separate. Colloid: a heterogeneous mixture with big particles, not even at a molecular level.  But be careful, it’s not all about the naked eye This is a heterogeneous mixture, The left-handed solution is because the gel balls are not in homogeneous and the right one the same phase as is not. Light passes without any water/perfectly mixed at a problem through homogeneous molecular level solutions and not when its heterogenous due to the big particles floating around Homogeneous vs Heterogeneous (liquids) Almost everything in nature is a mixture, even pure substances are alongside other impurities (like gold or argon in the air). How can we use them then? By separating them! Separating and treating materials is what has defined human history alongside language The first civilizations with metals where the first with weapons… Then… materials were used to transform our reality faster than we could imagine How did we got so good at making new stuff? Because we got to know the composition of our surroundings and how to separate it!  And what are those properties?? Well, you already know them! Physical and chemical properties! Physical property: a characteristic Chemical property: a of the object itself like mass, characteristic of flexibility, color. transformation like how easy a substance oxidizes, reacts, combusts, etc.  We are going to focus on separating mixtures, not compounds. This means, we will focus on physical properties that allow us to separate mixtures! Physical properties: ❖ Boiling Point ❖ Melting Point ❖ Density ❖ Particle Size ❖ Magnetic Properties ❖ Solubility Chemical change separation example, just for the fun of it  How to name a mixture? First, let’s see if it’s heterogenous or homogeneous. Then you state the phases of the solute(s) and then the phase of the solvent. Let’s imagine here the solvent is liquid and the star is a solid, and they produce a homogeneous solution. It’s then a solid-liquid homogeneous mixture. Solute, or the substance in Mixtures can have the particles lower quantity arranged in an indistinguishable in the mixture. Solvent, the substance in the way. A perfect mixture called There can be higher quantity in the homogeneous. If the particles several of mixture. Generally, there are not arranged in a perfect them. Like the can only be one. Like the way, all to the point we can see sugar in a water of the lemonade them, they are called lemonade heterogeneous.  Example using all of this new concepts: Evaporation technique! So the mixture to separate is a solid-liquid homogeneous mixture Homogeneous mixture: I can’t see the phases, they mixed Solvent: water perfectly at a molecular level Solute: Salt Phase: Solid Phase: liquid  Example using all of this new concepts: Evaporation technique! Salt boiling point: Water boiling 3000 °C point: 100 °C So the mixture to separate is a solid-liquid homogeneous mixture. But which physical property are we using when separating the water by boiling it form the salt? What about using evaporation to separate water from sand? Mixture  Let’s explore another technique: Liquid-Liquid Decantation So this decantation uses a difference of densities and solubilities as the physical property, it’s used for heterogeneous mixtures. In this case, a liquid-liquid heterogeneous mixture. It works by the simple use of gravity. Solvent? Let’s say 1 is a natural oil of some Phase? plants, and 2 is just water. Homogeneous or First: Which physical property heterogeneous? Solute? could allow us to separate it? Phase?  Let’s explore another technique: Solid-Liquid decantation This separation technique only works for particles bigger than 1000 Å (0.0001 mm), if not, they will never sink. (it doesn’t work for colloids) So this decantation uses a difference of densities and solubility as the physical property, it’s used for heterogeneous mixtures. In this case, a solid-liquid heterogeneous mixture. It works by the simple use of gravity. Solvent? Phase? Which physical property could Homogeneous or allow us to separate it? heterogeneous? Solute? Phase?  Magnetization Technique Scheme: sand from ferrite (iron dust) Magnetization uses a difference of magnetic properties as the physical property, it’s used for heterogeneous mixtures. It can bea solid-solid or solid-liquid heterogeneous mixture. It works by pulling the magnetic substance out of the mixture. Solvent? Phase? Which physical property could Homogeneous or allow us to separate it? heterogeneous? Solute? Phase?  Magnetic materials, why? Direction of the magnetic field Magnetic materials have their electrons much more aligned without any external help. Electrons are the ones that feel the magnetic field, so, a magnetic material will easily align to it and get attracted.  One of the most important separation techniques ever: Filtration Filtration uses the difference in particle size and solubility as the physical properties. It’s for solid-liquid heterogeneous mixtures. The main two types are gravity and vacuum filtration. Solvent? Phase? Which physical property could Homogeneous or allow us to separate it? heterogeneous? Solute? Phase? Filtration by gravity, the use of patience to filter a small solid out of a not very viscous liquid Gravity filtration is easy to set up, and requires as little as a funnel, a claw, the filter paper and two recipients. It can be really slow depending on how viscous the liquid is or if the solid is too big. Things are too slow or impossible? Just put a vacuum pump (Vacuum filtration) If things are running too slow, o you need really high quantities of water to be filtered, you can use a vacuum pump and a special funnel to help things out. The simplest of filtrations: Sieving technique Fast, and cheap.  Let’s explore sieving a little bit more Sieving uses a difference in particle size as the physical property It’s for solid–solid and solid-liquid heterogeneous mixtures. It uses sieves (dah) to separate substances by specific particle sizes. Solvent? Phase? Which physical property could Homogeneous or allow us to separate it? heterogeneous? Solute? Phase?  What happens when two liquids are soluble/miscible between them? Distillation! Solute: Methanol Solvent: water B.P.: 58 °C B.P. 100°C  Let’s explore a little bit more about distillation Simple distillation only works properly if the Distillation uses a difference in boiling points are at boiling point as the physical least 25 °C afar from property each other It’s for liquid -liquid homogeneous mixtures. The main two types are simple and fractioned distillation. Solvent? Phase? Which physical property could Homogeneous or allow us to separate it? heterogeneous? Solute? Phase?  What happens when boiling points are too similar? Fractional distillation Solute: Ethanol Solvent: water B.P.: 78 °C B.P. 100°C How good can fractional distillation get? As big as the column… Crystallization: the fancy evaporation technique for high purities When you slowly boil the solvent, eventually the solution will not stand having so much solute. If done properly, the solute will crystalize (agglomerate as orderly as possible) and you’ll get nice, pure crystals. Real life example! Evaporation vs Crystallization Evaporation is too aggressive, you evaporate all the solvent, leaving ALL the solids behind. You’ll have the salt… and ALL the other impurities that may have been dissolved. In crystallization, you slowly evaporate the solvent to ONLY get the solute in the bigger proportion/that’s less soluvle  Let’s explore crystallization Crystallization uses a difference in boiling point and solubility as the physical properties It’s for solid -liquid homogeneous mixtures. It slowly saturates the solution till the solute crystallizes. Solvent? Phase? Which physical property could Homogeneous or allow us to separate it? heterogeneous? Solute? Phase?