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Midterm EngSci, SEE P7, SEE P1, SEE P2, Pivot, SEE P4, SEE P5, SEE P6,…

- - - - Distance magnifier: bigger movement (to load) from a smaller movement (to effort)
      - Force magnifier: helps overcome large force (load) using a small force (effort)
    - - Definition: A turning effect between the bar and the pivot in a lever
      - EQUILIBRIUM
        
        principle of moment: anti-clockwise moments=clockwise moments
        
        which means balancing
      - 3 factors of moment
        
        1️⃣Distance (the length of the object to the pivot, in cm or m)
        
        2️⃣force created by the amount of mass (in N)
        
        Moment (Unit usually Ncm | Nm)
        
        Moment(Nm)=Force(N) x Distance(m)
    - - Pivot / Fulcrum (Where the bar rotates about)
      - Effort (a force you applied to the bar)
      - Load (weight of an object you lift)
    - - because...
  - - - Describing that "there is proportionality between the load applied to an object and the extended length of the object"
    - - In a nutshell: The load applied to the spring is proportional to the extension length of the spring.
  - - - Pressure itself (Unit presented in N/cm2 | N/m2)
      - force (in N)
      - Area (of the exerting object)
      - Pressure (N/m^2) = force (N) / Area (m^2)
    - - What affects gas pressure?
        
        adding more gas: increases the pressure, because more particles hit the balloon inside
        
        decreasing volume: increases pressure because more collision in smaller space
        
        increasing temperature: increases the pressure because particles move faster
      - Atmospheric pressure: air around us exerts gas pressure to our body all the time
        
        atmosphere pressure near earth's surface is bigger, because the air particles are pulled by gravity towards the earth. If the particles are together, the pressure is bigger
      - (Explained using a balloon) the collision of air particles (moving fast) with walls of the container
    - - liquid pressure at the bottom is the highest because of increasing weight of water
  - - - BALANCE is an important term
      - First law of motion: unless an external force is applied, stationary objects will remain stationary, and moving object will continue to move in a straight line at a steady speed
      - inertia(惯性）- object resist changes to their motion
    - - 比萨斜塔实验
      - thought experiment->you do not need a force to keep something moving!
    - - "When a force is removed, the object will stop."
      - incorrect. He didn't understand friction
      - object move only when they're pushed
  - - - Temperament
        
        increase heat = increase particle movements = diffuse quicker and more evenly
      - Air Convection(气流）
        
        distributes the particles more quickly = quicker diffusion
- - - - control the "gate" for the speed of letting the solution out from the decanting flask/seperating funnel
      - Solutions with high density: go to the bottom (vice versa)
      - In reality it can be done by simply pouring / skimming (吃火锅撇油沫)
      - Works for solutions made up of 2 or more liquids that have different densities and cannot react
    - - separate a solvent from a dissolved solid
      - How? When a solution is heated, the solvent evaporates and crystals of the solute are left behind.
    - - separate insoluble solids from liquids and gases using gravity and the filter medium which allows fluid to pass
    - - Uses a magnet to separate magnetic substances from non-magnetic substance
    - - Why pencil line? Pencil cannot be dissolved, while ink can
      - Can be used to identify different dyes/inks, because every ink's composition is unique, just like finger prints
      - In a nutshell: 拿个专用纸，铅笔画一条，马克笔点几点，放酒精里，正好到铅笔的刻度，然后静待花开～(上面是Kenny写的，详细过程看P5~)
      - Def: technique for separating the components, or solutes, of a mixture
      - (感兴趣的推荐看）
        Why separated? alcohol dissolves the mixture in a fluid solvent called the mobile phase, which carries it through a system on which a material called the stationary phase is fixed, and the constituents travel at different apparent velocities in the mobile fluid, causing them to separate based on the differential partitioning between the mobile and the stationary phases
    - - A use for distillation: filtrating unclean substances in seawater （但是效果不咋地）
      - Simple Distillation
        
        Also used for separating solutions with different boiling points, provided that boiling points differences is greater than 100C
        
        Use it for obtaining a pure solution, or obtaining solvent out of mixture
        
        平民窟办法：Conical flask + Delivery tube (一根玻璃管）+ Test tube + a beaker with full of ice (升降台看情况)
        
        Pig Condenser that costs hundreds of pounds with a delivery arm and a round-bottom flask
      - Fractional Distillation
        
        in petroleum refineries, crude oil is separated into different fractions based on their boiling points, such as gasoline, diesel fuel, kerosene, and jet fuel (industrial use)
        
        SEE P3
        
        efficient method for separating solution with different, similar boiling points
  - - - The boiling point and the melting point is the marker to identify pure substances
      - e.g. Experiment: Heating and cooling curve of stearic acid (liquid salol)
      - the boiling point and melting point of pure substance is always constant
        (representation in graph: steadily remain in a certain temperature in a certain amount of time)
      - Def: substance that is added to a sample to help identify or track it. Markers can be used to detect the presence of a particular chemical or to monitor the progress of a reaction.
    - - It can be an element or a compound
      - Element: pure substance made up of only 1 atom or molecule of an element
      - Pure substance: single kind of matter that has a fixed or constant structure and cannot be broken down or transformed into other kinds of matter
      - Compound: pure substance when two or more elements are combined chemically in a fixed ratio
  - - - Method 1: metal compound + acid -> metal salt + water
        
        Metal Salts depend on metal components and type of acid
      - EG. Lead Oxide + Hydrochloric Acid -> Lead Chloride + Water (PbO + 2HCl -> PbCl2 + H2O)
      - Method 2: metal carbonate+acid -> metal salt + water + carbon dioxide
      - EG. Lead Carbonate + Sulphuric Acid -> Lead Sulphate + Water + Carbon Dioxide (PbCO3 + H2SO4 -> PbSO4 + H2O + CO2)
      - Steps: saturated solution->filter solution (residue, filter paper, funnel, conical flask, filtrate)->evaporate (evaporating dish)
    - - Def: Metal and Oxygen reacts
      - metal+oxygen->metal oxide
      - eg. 2Mg + O2 = 2(MgO)
      - eg. 4Na+O2->2(Na2O)
      - *uses equation balancing
    - - 1- irreversible
      - 2-new substance created
      - 3-Rearrangement of Structure
      - How to identify if a chemical reaction has taken place: temperature, smell, color, gas/heat given out, pH changes, fizzling (or not), change of property etc.
    - - Def: soluble substance + soluble substance reaching together to produce an insoluble substance(which is the ppt) and a soluble substance
        
        soluble+soluble->insoluble+soluble
      - You can observe the ppt in these three ways:
        
        1-ring at the top of solution
        
        2-at the bottom
        
        3-sporadic particles in the middle
      - eg. Sodium Hydroxide + Magnesium Nitrate = Magnesium Hydroxide(insoluble)+ Sodium Nitrate
      - eg. Potassium Iodide + Lead Nitrate -> Lead Iodide (insoluble) + Potassium Nitrate
    - - Def: the metal higher in the reactivity series displaces (push away from compound) the metal in the metal compound that is lower
        
        metal (lower) compound + metal (higher)-> metal (higher) compound + metal (lower)
      - eg. Iron Sulphate + Zinc = Zinc Sulphate + Iron
      - The higher the higher element is (in the reactivity series), the bigger the reaction
      - Common elements in the reactivity series (list of metals arranged in order of their reactivity from highest to lowest)
        
        (most reactive) Potassium
        
        Sodium
        
        Calcium
        
        Magnesium
        
        Zinc
        
        Iron
        
        Tin
        
        Copper
        
        (least reactive) Gold
        
        Silver
        
        Aluminum
        
        Carbon
      - If the metal in the compound is higher in reacting series then the other metal, no displacement happens
    - - Method: metal + acid -> metal salt + hydrogen
      - common acids ->metal salt
        
        Hydrochloric (HCl) -> Chloride
        
        Sulphuric (H2SO4) -> Sulphate
        
        Nitric (HNO3) -> Nitrate
      - The lower the pH of Hydrogen, the higher the concentration, which means bigger reaction, vice versa
      - eg. Zinc + Hydrochloric Acid -> Zinc Chloride + Hydrogen (Zn + 2HCl -> ZnCl2 + H2)
      - eg. Magnesium + Nitric Acid -> Magnesium Nitrate + Hydrogen (2Mg + 2HNO3 -> 2MgNO3 + H2)
      - "a lit spill will combust with hydrogen with a squeaky pop" (a lit spill is a test for the presence of hydrogen; When brought to a flame, a hydrogen will produce a squeaky pop.
  - - - Mg - Atomic Mass: 24
        
        it's based on the sum of protons and neutrons
      - Mg- Atomic Number: 12
        
        equals the number of electrons
        
        distribution pattern: 1st layer maximum 2; 2nd layer maximum 8; 3rd layer maximum 8. When the electron exceeds the maximum amount, it's in the next layer
    - - process of ensuring that the number of atoms of each element is the same on both sides of the equation (The atom is acquired by multiplying the coefficient and the subscript) Penvose: What you start with what you must end with
    - - transition(al) elements
        
        79-Gold Au
        
        47-Silver Ag
        
        30-Zinc Zn
        
        29-Copper Cu
        
        28-Nickel Ni
        
        27-Cobalt Co
        
        26-Iron Fe
        
        80-Mercury Hg
        
        25- Manganese Mn
      - 7th Group
        
        17-Chlorine Cl
      - 6th Group
        
        16-Sulfur S
        
        8-Oxygen O
      - 5th Group
        
        15-Phosphorus P
        
        7-Nitrogen N
      - 4th Group
        
        50-Tin Sn
        
        6-Carbon C
        
        14-Silicon Si
      - 3rd Group
        
        13- Aluminum Al
      - 2nd Group
        
        20-Calcium Ca
        
        12-Magnesium Mg
      - 1st Group
        
        19-Potassium K
        
        11-Sodium Na
        
        3-Lithium Li
        
        1-Hydrogen H
    - - Iron-green
      - Copper-blue
      - Gold-gold
      - Cobalt-red