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GCSE: Patterns of Behaviour

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  1. Chemistry coursework. Rates of reaction

    PREDICTIONS From What You Already Know What Do You Think Will Happen? How Do You Think This Will Happen? I predict that as the concentration of the sodium thiosulpahte decreases, the rate of reaction of the experiment will decrease i.e. the concentration is directly proportional to the rate (conc ? rate). I predict this will happen because in concentrated sodium thiosulpahte there are more sodium particles. This means there is a greater chance of a sodium particle hitting an acid atom with a sufficient amount of energy to force a reaction. The greater the amount of successful collisions the faster the rate of reaction.

    • Word count: 1547
  2. Plan an experiment to investigate the effect of changing the concentration of sodium thiosulphate on the reaction between hydrochloric acid and sodium thiosulphate.

    As soon as enough sulphur was formed and the cross disappeared and I stopped the timer. I recorded the time and repeated this for each concentration of sodium thiosulphate. These results would have been rather inaccurate because the apparatus I used was crude. The measuring cylinders and "paper with cross" relied on my eyesight and judgement which are subjective and aren't perfect. The time recorded was also inaccurate because I couldn't have started the timer and stopped it at exactly the same point each time.

    • Word count: 1113
  3. chemistry rate of reaction

    Speed at which a chemical reaction proceeds. It is usually expressed in terms of the concentration of a reactant used, or product formed, in unit time. The rate of a reaction may be affected by the concentration of the reactants, the temperature of the reactants or the amount of light (photochemical reactions), and the presence of a catalyst. If the reaction is entirely in the gas state, the rate is affected by pressure, and, where one of the reactants is a solid, it is affected by the particle size.

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  4. Investigating a single factor that affects the rate of reaction between marble chips and hydrochloric acid.

    Succesful collisions are much more likely to happen when there are more particles present. The higher the number of particles present means the higher number of succesful collisons will occur. The higher the number of succesful collisions, the faster the rate of reaction, ie. The quicker time it takes for the reaction to take place. The word equation for this investiagtion (marble chips and hydrochloric acid) is: CaCO ? + 2HCl H2O + CO2 + CaCl Preliminary Investigation - Aim - To investigate which size of marble chips give the largest range of results, ie the best results, for the main investigation.

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  5. Chemistry - Rate of Reaction

    This is all because when a chemical reaction takes place chemical bonds are broken and new ones are formed. To break bonds energy must be supplied. In this case the energy is in a chemical form which is in the hydrochloric acid. But also in this experiment new bonds will be formed and when this happens energy is given off. In this experiment this energy is in the form of heat. This is why it is called an exothermic reaction. Chemical reactions only take place when the reacting particles collide with each other, and collide with enough energy to react.

    • Word count: 1522
  6. Halogenoalkanesshow how the rate of reaction of the halogenoalkanes changes in respect to the C-X bond, where the C is the carbon and the X is the halogen (C-Cl, C-Br, C-I).

    The rate of substitution depends on the halogen due to the strength of the C?X bond. There are 3 main types of nucleophilic reaction, one involves reacting them with an excess concentrated solution of ammonia in ethanol under pressure, this one shall not be used since it will constantly substitute the chemicals and the end result will be a huge range of amines. Another is with cyanide ions, which is not being used due to cyanide being extremely dangerous. Finally, the reaction can be done using hydrolysis with hydroxide ions which is our preferred method.

    • Word count: 1642
  7. Treatment of Results

    = 0.72 = 0.12 6 y = 3.612 = 0.602 6 The equation for the least squares regression is in the algebraic form: y = a + bx where a is the intercept of the line on the y-axis and b is the slope of the line. [1] [2] b = 0.2103 = 5.2184 0.0403 a = 0.602 - (5.2184 x 0.12) = -0.0242 Therefore the equation for the least squares regression line is: y = 5.2184x - 0.0242 Part 2 Interference Studies Concentration /mol.dm-3 Absorbance Acetylsalicylate 0.0261 0.154 Salicylamide 0.2204 1.081 Caffeine -0.0056 0.004 Acetaminophen -0.0058 0.002 The table above shows the results obtained for this part of the investigation.

    • Word count: 1074
  8. To investigate how concentration of acid affects the rate of a reaction. Hypothesis: I predict that as the concentration of the acid increases

    there is a lower chance the HCA and SCC particles will bump, therefore only a small amount of reactions will occur, given off a small amount of carbon dioxide. I think if the amount of HCA particles are increased the will be more chance of them colliding with the SSC, and by doing so cause will cause more reactions. I assume If I make the concentration twice as strong the reaction will be twice as fast this is because there is twice as many particles of HCA that could collide with the SCC.

    • Word count: 1314
  9. Halogenoalkanes

    What is a nucleophilic substitution reaction? The most common type of reaction found in halogenoalkanes is a substitution reaction. This substitution involves the halogens. They are replaced by a variety of other groups. The halogen leaves as a halide ion. For this to happen though it means that the replacing group must donate an electron pair. A chemical that has one or more lone pairs donates an electron pair and is known as a nucleophile. The electrons are donated to the slightly positive carbon atom. A new covalent bond is formed between the carbon and the nucleophile that replaced the halogen.

    • Word count: 1175
  10. Investigation to find out how the rate of reaction between Sodium Thiosulphate and hydrochloric acid that is affected by changing the concentration.

    This increases the probability of reactant particles colliding with each other. Diagram Method Firstly, we drew a black cross on a white piece of paper. Then, we put 10 cm� of hydrochloric acid in a conical flask, and then put the conical flask on the black cross on the paper. We then added 50 cm� of sodium thiosulphate to the hydrochloric acid, and at this time we do not need to add any water. Immediately, we started the stopwatch. We then waited for the black cross to be completely obscured by the mixture.

    • Word count: 1992
  11. Look at your new

    Small Surface area. It is hard for the particles to gain Energy because they are all bunched together and there is no room for the particles to gain energy, move and collide, this slows down the rate of reaction. Large Surface area It is a lot easier for the particles in this diagram to gain energy, move and cause more collisions because they are all spaced out (Large surface area). The particles will gain the activation energy needed to cause the product to be formed quicker, and so the rate of reaction will increase.

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  12. Investigation on the rate of Reaction of Sodium Thiosulphate and Hydrochloric Acid

    * The thickness and darkness of the cross - this had to stay the same because if the cross was changed to a thicker and darker cross alter in the experiment it would lead to an unfair test because the bigger and darker cross would be easier to see. * Depth of the liquid in the solution - to keep the depth the same I used the same volume of solution; the same size of the conical flask; and the same shape conical flask.

    • Word count: 1402
  13. Some fuels are mixed with oxidising agents to produce explosives. An explosive such as gunpowder is designed to carry their own oxygen supply taking gunpowder as the example the potassium nitrate in the gunpowder acts as an oxidiser

    The greater the tension contained in this bonds, the more powerful the detonation will be, once they are broken apart. Some explosive mixtures oxidise faster than other because more oxygen is available.{4,3} Describe how UK methods of manufacture of propanone have changed since the beginning of the First World War. During the First World War propanone was manufactured by the dry distillation of wood in a process that excluded air. This method was not effective and not enough propanone could be made.

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  14. Oxidation reactions can be used to cause explosions due to the fact that these reactions can produce large volumes of products from a relatively small volume of reactants. The products mainly consist of hot gasses

    The oxidiser contains the oxygen needed for the reaction, instead of taking oxygen from the air, which means the reaction would be slower; this means the reaction can take place within a fraction of a second. During the First World War British shells had to be rationed, this is because of a lack propanone used in making cordite, the main propellant in artillery shells. Before the war the British had to import propanone, as they had no means of producing their own.

    • Word count: 1252
  15. Investigate how varying the concentration of Sodium thiosulphate solution affects the rate of reaction with Hydrochloric Acid.

    A more concentrated substance has more molecules for a given volume than a more dilute substance. Because there are more molecules about, the frequency of successful collisions is greater, and the reactions happen faster. Prediction I predict that when I add more water to the sodium thiosulphate solution, the time it takes for the cross to disappear will lengthen. I predict this because, for particles to react they must collide with each other. If there is a higher concentration of sodium thiosulphate particles in a given volume there, is a higher chance of the particles colliding together and reacting.

    • Word count: 1262
  16. Investigate the affect of temperature of sodium thiosulfate and hydrochloric acid against rates of reaction.

    Therefore, from my results I can say that, the higher the temperature, the faster the collision rate. There was a systematic error on the 46�c and 49�c temperatures, as they are both the same. From my results, the 49�c temperature should have affected the rate of reaction quicker, because the temperature is higher. I also found an error when I did my 39�c test. The result is 5 seconds slower than the 38�c test. The result should have been 5 seconds quicker with the 39�c test.

    • Word count: 1122
  17. The object of this investigation is to determine the enthalpy change for the reaction CaCO3 (s) → CaO (s) + CO2 (g) by an indirect method based on Hess' Law. Hess's law states that the enthalpy change for any chemical reaction

    whole number as it is unrealistic to measure to a point of a ?C with this type of thermometer and the masses rounded up to 2 decimal places for greater accuracy. Calculations It's possible to use the formula E = mc ?T, where E = energy transferred, m = mass of HCl, c= specific heat capacity of HCl and ?T = temperature change. This formula can be used for calculating the energy transferred in the following reactions ? ?H1, CaCO3 (s)

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    A common misconception is that an increase in concentration increases the speed of the particles moving around in it or the amount of energy they have, this is not the case as the increase in concentration merely increases the surface area which facilitates the reaction; this can be further helped if the particles being used are of a small size. See diagram below which compares small particle size with the larger particle size. The hypothesis of this experiment is that an increase in the concentrations of Magnesium and Hydrochloric acid will increase the rate of reaction which is measured by the amount of hydrogen produced.

    • Word count: 1615
  19. When KMnO acts as an oxidizing agent when it comes in contact with 1 butanol, 2 butanol and t- butyl which of these agents will become primary, secondary or tertiary alcohol?

    Strong reagents will further oxidize the aldehyde into a carboxylic acid. Tertiary alcohols cannot be oxidized. The purpose of this lab was to determine the reaction of 1, 2 butanol and t- butyl when KMnO, and 2ml of acid was added to see which alcohol was primary, secondary or tertiary. Hypothesis: I believe that 1 butanol will be primary because when reacted with KMnO it will create a aldehyde and then a carboxylic acid, 2 butanol will be secondary because when reacted with KMnO it will create a ketone and then no reaction, and t- butyl will be tertiary because when reacted with KMnO it will create no reaction.

    • Word count: 1249
  20. The history of the periodic table

    Gallium is considered to be an unusual element because of its properties.

    • Word count: 1114
  21. The aim of this experiment is to investigate what affects the rate of reaction between Sodium Thiosu

    Preliminary Work I am going to obtain a number of preliminary results to find out which is the best concentration of Sodium Thiosulphate, Hydrochloric Acid and water. Preliminary Results ST (cm3) Water (cm3) HCl (cm3) Time Seconds (s) 50 0 10 28 40 10 10 45 30 20 10 62 20 30 10 100 10 40 10 239 I have decided to use a concentration of 30cm3 of Sodium Thiosulphate, 20cm3 of water and 10cm3 of Hydrochloric Acid. I have chosen to use this concentration because it enables me to obtain results from a reaction which takes about 60 - 90 seconds at room temperature which is just what I want.

    • Word count: 1579
  22. Explain, giving examples from the articles, what is meant by oxidation and show how oxidation reactions are used to cause explosions. Outline reasons why some explosive mixtures oxidise faster than others.

    The power of the explosion is made greater by confining the reaction inside a restricted space e.g. Cannon. Fuels used in fireworks; Potassium Chloride (KClO3) and rockets; Hydrogen Peroxide (H2O2) are mixed with oxidisers to produce explosions. Some explosive mixtures oxidise faster than others if the reacting element(s) gains more oxygen and has a greater oxidation state. * Give an account of the development of chemical compounds for use in explosives. Describe the advantages of each new chemical explosive over its predecessors, and describe how the explosives were adapted to make them safer and more effective.

    • Word count: 1455
  23. Investigating the rate of reaction between Sodium Thiosulphate and Hydrochloric Acid

    With this experiment, I must take into account that temperature has an affect on reaction times so tests must be carried out at roughly the same time of day. Range and Number of Results: I will carry out this investigation using five different volumes of Sodium Thiosulphate: 50cm�, 35cm�, 20cm�, 15cm� and 10cm�. This will enable me to obtain a wide range of results, achieve a better picture of the nature of the reaction I am investigating and make the graph more accurate.

    • Word count: 1285
  24. To Investigate how changing the concentration Affects the Rate of Reaction between Hydrochloric Acid and Magnesium

    Bonds are being shared which means that the covalent bonds have less ions to share. With a more concentrated acid, the number of acid particles is greater, so the number of collisions is greater and the rate of the reaction is higher, thus they will collide with each other more often. Changing the concentration of the acid does not change how quickly the particles are moving (i.e. it doesn't increase the amount of energy they have). There are two ways to measure the rate of a reaction: 1. Measure the rate that a reactant is used up, or 2.

    • Word count: 1848

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