Mass Spectrometer.

Mass Spectrometer Used to determine * the relative isotopic masses and abundance of isotopes * the relative molecular mass (Mr) and abundance of the organic compound Principles of the mass spectrometer * Apparatus enclosed in total vacuum, so that there are no colisions between the sample being investigated and the atmospheric air or the residue from previous samples. * Vacuum pump is to reduce pressure so less thermal energy is needed to vaporise the sample. The pump is to remove any traces of the previous sample traces of the air. * Sample under analysis must be vaparised i.e. converted to gaseous state. This is achieved by heating it in the furnace. * Sample then enters the ionisation chamber; here the sample is bombarded by a beam of high energy electrons. A beam of these high energy electrons bombard the atoms causing them to loose an electron. A removal of an electron from the atom is known as ionisation. This results in the formation of positively charged ions (cations), mainly single charged ions. If the sample is simple the molecules are ionised by being bomdarded by high energy electrons, causing bonds to vibrate and weaken, some bonds between molecules to produce small pieces of the original molecule known as smaller fragments and/or free radicals. Smaller pieces of the original lecule are known as moecular

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  • Level: GCSE
  • Subject: Science
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The Periodic Table

The Periodic Table was developed in stages; the first person that attempted to classify elements in relation to their atomic mass was Johann Döbereiner. Döbereiner noticed similar properties between known elements. Theses similarities occurred in groups of threes and were known as 'triads'. The atomic weight of the middle element in each triad is approximately an average of the others. In 1863 John Newlands put the known elements in order of atomic weight and noticed that every eighth element had similar properties, he called this the Law of Octaves. After about 20 elements the table became ragged and some elements had identical places whilst others were incorrect because of inaccurate weights. Furthermore Newlands left no gaps for any unknown elements. Dimitri Mendeleev amended some atomic weight values and left gaps for any undiscovered elements. Mendeleev predicted properties of five elements that should be discovered, within 15 years of his predictions three of these elements had been discovered. One of the unknown elements was called Eka-aluminium today known as Gallium. Below a table compares the predictions made by Mendeleev about gallium with what is now known. Table 1 Comparing Mendeleev's predictions with the properties of element 31, gallium eka-aluminium (Ea) gallium (Ga) atomic weight About 68 69.72 density of solid 6.0g cm-3 5.904g cm-3

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  • Level: GCSE
  • Subject: Science
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Investigatin the Rate of Reaction

Investigating the Rate of Reaction Aim To investigate the effect of concentration on the rate of reaction between sodium thiosulphate and hydrochloric acid. Prediction I predict that as the concentration of the sodium thiosulphate is increased, the rate of reaction will increase. This is because there are more particles, therefore more chances of collisions. The graph that is going to be drawn in my analysis will have a positive correlation. Also it might be curved as the increase in rate of reaction which will not be exactly the same as the concentration of the sodium thiosulphate. This probably will be because there are more chances of collisions. So when the concentration will increase then the particles would have more energy and therefore it will move faster. This is the reason why they will collide more often. Equipment Substances that we're going to use Pipette Hydrochloric acid Stopwatch Sodium thiosulphate Spotting tile Water Conical flask Funnel Burette Method . Set up apparatus as shown in the diagram. 2. Measure 25cm3 of hydrochloric acid and pour into conical flask. 3. Add 25cm3 of 0.2 mol dm-3 of Na2S2O3 to hydrochloric acid and immediately start stopwatch. 4. When the cross disappears stop the stopwatch. 5. Record the results. 6. Repeat steps 1-5 three more times. 7. Repeat step 1-6 for 0.4, 0.6, 0.8, 1.0 mol dm -3 Na2S2O3.

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  • Level: GCSE
  • Subject: Science
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Physics : To find the center of mass of various shapes.

PHYSICS LAB CENTER OF MASS Aim: To find the center of mass of various shapes. Shapes: Center of Mass: Towards the middle, a little eastwards. Where all edges are furthest possible. Center of Gravity: In the middle of the width of the shape, since it's symmetrical. Towards the lower part of it vertically. Center of Mass: Totally symmetrical shape, therefore center of mass is exactly in the center. Center of Mass: Furthest possible away from each edge, towards the middle of the shape. Conclusion: All the shapes have the center of mass towards the middle. They all have the center of mass the furthest from each edge as possible. The shapes that are symmetrical have the center of mass in the middle, whereas the square shape has it exactly in its center, since its symmetrical anyway you look at it. The triangle, vertically symmetrical, also has a center of mass in its middle horizontally, although not vertically. Vertically its center of mass is nearer to the bottom, probably making the surface area before and after the center of mass equal. Since on top its thinner but longer and at the bottom its wider but lower. The fact that the center of mass of the object is towards the middle tells us that the pull of gravity is focused in the middle of the object. Since the gravity is focused on the center of mass, this means that all of the forces acting upon the body cancel out.

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  • Level: GCSE
  • Subject: Science
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Iron Oxalate Lab

Marina Horta Iron Oxalate Lab 10/22/09 Abstract; The purpose of this lab was to synthesize, isolate, and determine Fe content of a complex; and calculate the formula of the Potassium Oxalate Iron(III) Complex using chemical analyses. This lab used filtration, titration, acid base reactions, redox , synthesis, dilutions , beers law and red tide computer system to establish that the final formula for the complex was K3[Fe(C2O4)3] •2 H2O. Introduction; Part 1; The purpose of part 1 to synthesize, purify and, mass crystals of potassium oxalate ferrate (III) complex. Potassium oxalate ferrate (III) is a complex, an ion consisting of a ligand and a metal covalently bonded together. A ligand is an ion with the tendency to bond with metals because it typically donates electron pairs. This relationship between metals and ligands is only one of the key components for the synthesis of the crystals. For the precipitation of the complex ion alcohol was used to reduce solubility, Part: 2 Part two determines the percent oxalate in the complex produced in the previous lab. Using volumetric analysis a method (similar to gravimetric analyses) in which the volume of a known

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  • Level: GCSE
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Thermal Decomposition of copper carbonate

Thermal Decomposition of copper carbonate Aim: Copper has two oxides, Cu2O, and CuO. Copper carbonate, CuCO3 decomposes on heating to form one of these oxides and an equation can be written for each possible reaction Equation 1: 2CuCO3 (s) ? Cu2O (s) + 2CO2 (g) + 1/2 O2 (g) Equation 2: CuCO3 (s) ? CuO (s) + CO2 (g) The aim of this experiment is to prove which equation is correct. This can be done by volumetric analysis i.e. calculating the volume of gas produced. This is then compared to the calculated volume of gas produced in each equation and the equation with the nearest volume of gas is correct. This is a thermal decomposition reaction and when an element like copper can form two oxides, which one forms is based on the stability of the compound formed. The more stable the compound, the more likely it is to form. The stability of a compound with respect to its elements can be predicted by the ?Hf (molar heat of formation). This is the energy change when 1 mole of a compound is formed from its elements. If it is exothermic (negative), then the compound is stable with respect to its elements. If it is endothermic (positive), then the compound is unstable with respect to its elements. In general, the lower the value of ?Hf, the greater the energetic stability of the compound with respect to its elements. The molar heat of formation of CuO is -155.2, and the molar

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  • Level: GCSE
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A discussion of Atoms.

Atoms There are 112 elements although elements 110-112 are as yet unnamed. These 112 elements are organized in the periodic table: The modern chemical symbols were introduced by Berzelius. Rows of elements are called "periods" and columns of elements are called "groups" (1A, 2A 3B etc.). There are three general classes of elements distinguished by their physical properties: the metals (generally shiny and conduct electricity), the non metals (not shiny, sometimes gasses at STP and poor conductors of electricity) and the metalloids (properties in between those of metals and non metals.). Some groups have special names: Group 1A: Alkali metals Group 2A: Alkali earth metals Groups 3B-2B: Transition metals Group 7A: Halogens Group 8A: Noble gases Many of the heavier elements are unstable - which means that the atoms of those elements break apart very quickly. Elements within a group share similar chemical properties. Other chemical and physical properties of the elements can be deduced from their position in the periodic table. The structure of the periodic table and thus their chemical and physical properties is directly related to their atomic structure. Atomic Weights Most elements can be found on earth (with the exception of those elements that too unstable and thus must be synthesized in the laboratory). Since all elements have isotopes then we must consider how

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  • Level: GCSE
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Osmosis in potatoes and how various concentrations of salt solution in which potato chips are placed, affect osmosis in the cells.

Biology Coursework: osmosis in potatoes and how various concentrations of salt solution in which potato chips are placed, affect osmosis in the cells. Aim: The aim of this investigation is to see how changing the concentration of salt in a solution will affect osmosis in potatoes. Variables: * The temperature will affect osmosis in cells because the potatoes might cook only a bit and this should cause the tiny paws in the potato to close. * The amount of salt in the concentration will affect the experiment because the greater the amount on the other side, the faster the water moves from ones side to the other. * The surface area of the potato chips is another variable. A larger surface area will be able to absorb more water and there will be more of a permeable surface for the water to move through. * The volume of water is also important. A weaker concentration of salt will affect the rate of reaction because osmosis is the passage of water from a region of high water concentration through a semi permeable membrane to a region of low water concentration. I am going to investigate the concentration of salt. I think that this is the easiest for me to do and I also think that I can get a good set of results from it. My predication: Osmosis is the passage of water from a region of high water concentration through a semi permeable membrane to a region of low water

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  • Level: GCSE
  • Subject: Science
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Does god exist: my opinion?

Does god exist: my opinion? After studying God's existence and the reasons why people think that god does or doesn't exist I have come to the conclusion that I am unsure about his existence. I feel there are some reasons that justify god's existence and other things that don't. I therefore class myself as an agnostic. There are several reasons why I believe that God exists. One idea I have is that because there is so much in the world that is bad I believe there must be something to balance this that is completely good. I believe that God is this. I also think that is each and very person is unique then everyone's life must have a meaning or a purpose and it is God who had given us this. There are many things in life that no matter how hard we try we can not explain. If God exists he provides an answer and explanation to all of these mysteries. This also links in with the idea that life is so complex and diverse many people including myself find it hard to get our heads around the fact the world and everything in is the result of an accident or freak of nature. The fact that the Big Bang just occurred and everything formed is quite a difficult idea to comprehend. Some theories that I feel back up my ideas are Thomas Aquinas' cosmological argument. He states that something can not come from nothing. His argument also says that every effect must have a cause. This makes sense

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  • Level: GCSE
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Periodicity three :Trend in the physical properties of the alkaline earth metals.

Group II - The Alkaline Earth Metals. (Variation in Physical Properties) Beryllium (Be) (Atomic number = 4) s2 2s2 Magnesium (Mg) (Atomic number =12) s2 2s2 2p6 3s2 Calcium (Ca) (atomic number = 20) s2 2s2 2p6 3s2 3p6 4s2 Strontium (Sr) (Atomic number = 38) s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2 Barium (Ba) (Atomic number = 56) 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s2 Notice that each alkaline earth metal has two electrons in its outermost shell and that these electrons occupy s orbitals. ) Trends in the physical properties of the alkaline earth metals. a) The trend in atomic radius The graph below shows the trend in atomic radius for the alkaline earth metals. Notice that as the atomic number increases the size of the atoms also increase. In other words as group two is descended, atomic radius increases Why is this? Look closely at the electronic structures of each element provided for you at the start of this section. You should see that as you go down the group the number of electron shells increases by one each time (for example the outer shell for beryllium is the second shell and for magnesium it is the third etc) This means that progressively the outer electrons are further from the nucleus and so since atomic radius is the distance from the centre of the atom to the perimeter of the outermost electron shell, the atoms become

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  • Level: GCSE
  • Subject: Science
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