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International Baccalaureate: Chemistry

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  • Peer Reviewed essays 1
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  1. Molar Heat combustion chemistry - investigate the effect of molar mass on the molar heat of combustion of adjacent members of a homologous alcohol series.

    Measure 100g of water into an aluminium can and clamp it in position above the spirit burner. 3. Insert the thermometer and cotton wool plug into opening of the can (ensure that the thermometer does not touch the bottom of the can). 4. Record the initial temperature of the water. 5. Select an alcohol burner and ensure that there is at least 20 cm3 of the alcohol in the burner. 6. Weigh the burner and its contents. 7. Place the burner under the centre of the flask (shield from drafts)

    • Word count: 2721
  2. Aim: Using an iodine clock reaction to find the order of hydrogen peroxide and Ethanoic acid present in that experiment.

    and in another 5 experiments, the Ethanoic Acid was changed and the H2O2 was held constant among others. Time Dependent The time of the reaction is being measured. The clock was started when the two solutions came into contact and was stopped after the solution had finished changing colour. Temperature Controlled The experiments were all carried out at room temperature, in this case 20�C. Volume of Starch Solution Controlled The same volume of starch solution was added in each experiment, keeping the variable controlled.

    • Word count: 2085
  3. Indicator Lab Report - investigating acid-base reactions

    32.0 1.84 34.0 1.95 36.0 2.08 38.0 2.25 40.0 2.51 pH Change with Volume: Titrating HCl with NH3 Volume of Base �0.05cm3 pH �0.005 0.0 2.67 2.0 3.15 4.0 3.46 6.0 3.66 8.0 3.82 10.0 3.95 12.0 4.06 14.0 4.15 16.0 4.25 18.0 4.33 20.0 4.41 22.0 4.48 24.0 4.57 26.0 4.65 28.0 4.73 30.0 4.82 As the tables on the previous page show, there was no obvious equivalence point for the latter two reactions. This will be explored in the data processing section. Indicator Justification Phenolphthalein and methyl orange are the two indicators that were used during this investigation.

    • Word count: 2588
  4. A Comparison of Strong and Weak Acids and Bases

    Table 1.4: The order in which the speed of reaction occurs between the acids and the CaCO3(aq). Speed of Reaction Name of respective acid Concentration of the acid / mol dm-3 1 HNO3(aq) 1.00 2 HCl(aq) 1.00 3 CH3COOH(aq) 1.00 4 H2SO4(aq) 1.00 5 HCl(aq) 0.10 6 HCl(aq) 0.01 * Approximately 2.0cm3 of each was used. Table 1.5: The observations upon reacting different solutions and concentrations of acid with the magnesium ribbon, Mg(s). Before magnesium ribbon is placed in acid solutions. During the reaction between magnesium ribbon and acid solutions After reaction has stopped All solutions were colourless Odourless gas was produced.

    • Word count: 2752
  5. Atomic Structure Notes

    The nuclei of radioisotopes breaks down spontaneously emitting radiation - either ???? or ?. Their uses include nuclear power generation, sterilisation of medical equipment, finding cracks and stresses in metal, and the preservation of food. Some radioisotopes of certain elements are particularly useful. Isotope Use 14C Carbon dating 60Co Radiotherapy - treatment of cancer patients 131I and 125I Tracers in medicine for diagnosing and treating illnesses Mass spectrometry A mass spectrometer is a machine that can: * measure the relative masses of different isotopes * measure the relative abundances of the different isotopes in a sample of an element.

    • Word count: 2403
  6. Free essay

    Energy content Cal/g

    12. Immediately place the burning food sample under the can of water. 13. Determine the temperature change of the water 14. Repeat the procedure as many times as necessary to obtain appropriate data for analysis. 15. Determine the energy content in the food in Cal/g. 16. Using the nutrition information on the back of the package , determine the percent error. Calculations notes: *In order to calculate Theoretical energy content 1 oz was considered to be approximately 28.35g * Note it is assumed that the mass of the water inside the calorimeter did not change throughout the course of the reaction Raw Data Table Trial Initial Mass of food (+/- .005g)

    • Word count: 2006
  7. Strong and Weak Acids And Bases

    Sodium Hydroxide 11.0 Green 11.83 Table 2 - Percent Errors and Percent Uncertainties with ph Paper Substance Percent Error | Theoretical - experimental | x 100 = percent error Theoretical Percent Uncertainty 0.1 M hydrochloric acid | 1.0 - 1.0 | x 100 = 0.0 % error 1 0.5 x 100 = 50.0 % uncertainty 1 0.01 M hydrochloric acid | 2.0 - 2.0 | x 100 = 0.0 % error 2 0.5 x 100 = 25.0 % uncertainty 2 0.1 M ethanoic acid | 2.9 - 3.0 | x 100 = 3.4 % error 2.9 0.5 x 100 =

    • Word count: 2998
  8. The Enthalpy of Neutralization

    -12.5 � 1.0 -13 � 1.0 Experiment 4.1 - The reaction between sulfuric acid and 2.00mol�dm-3 sodium hydroxide. Table 4.1: Temperature of H2SO4 and NaOH, separately and after mixing Reagent Temperature (�C) for Trial 1 Temperature (�C) for Trial 2 25cm3 of 2.00mol�dm-3 H2SO4 21 � 0.5 21 � 0.5 25cm3 of 2.00mol�dm-3NaOH 21 � 0.5 21 � 0.5 Mixture of H2SO4 and NaOH 33 � 0.5 33.5 � 0.5 Change in temperature (?T) -12 � 1.0 -12.5 � 1.0 Experiment 4.2 - The reaction between sulfuric acid and 4.00mol�dm-3 sodium hydroxide. Table 4.2: Temperature of H2SO4 and NaOH, separately and after mixing Reagent Temperature (�C)

    • Word count: 2740
  9. THE CATALYTIC DECOMPOSITION OF HYDROGEN PEROXIDE

    This is because catalysts help to overcome activation energy and the more catalyst used, the more activation energy will be overcome and thus the reaction will be faster. However, I also expected that eventually there would be a point where adding any more Manganese (V) Oxide would not increase the speed of reaction any further. This would be because there would be too little hydrogen peroxide to react with the catalyst, the catalyst also only helps to overcome activation energy and does not in fact increase the speed of reaction once the reaction has started.

    • Word count: 2137
  10. Determination of potassium hydrogen carbonate into potassium carbonate

    KHCO3 The temperatures of each trial at � 0.10K Trials Initial � 0.5% After � 0.7% Change is ( + ) � 1.2% 1 21.700 14.300 7.4 2 22.000 14.200 7.8 The average can be calculated for the temperature by using the same equation as shown above. Therefore: Average of the temperature change of KHCO3 = (7.4 + 7.8)/2 = 7.6 0K � 1.2% When using a thermometer that measures � 0.1 K the uncertainty shown in the table of trial 1 for example, K2CO3 measures 21.7000K will equal to (0.1/21.600) X 100 = � 0.5% for trial 2: (0.1/14.300)

    • Word count: 2168
  11. Aim. To find the identity of X(OH)2 (a group II metal hydroxide) by determining its solubility from a titration with 0.05 mol dm-3 HCL

    i.e (the beginning of the graph). At the equivalence point moles of acid equal mole of base, and the solution contains only water and salt from the cation of the base and the anion of the acid. i.e. the vertical part of the curve in the graph. At that point, a tiny amount of alkali casuses a sudden, big change in pH. i.e. neutralised. Also shown in the graph are methyl orange and phenolpthalein. These two are both indicators that are often used for acid-base titrations.

    • Word count: 2220
  12. Rates of Reaction Lab

    As the reactants get used up, their concentration decreases. This explain why the rate get slower until stops to a constant value as the reaction proceeds. Variables Independent Variable: Concentration of hydrochloric acid (HCl) Dependent Variable: Volume of hydrogen (H2) gas produced/collected Controlled Variable: Temperature, mass of zinc used, temperature of the hydrochloric acid, volume of the hydrochloric acid How it will be controlled Room Temperature Keeping the air conditioning at the same temperature throughout the entire experiment by measuring it with a thermometer.

    • Word count: 2387
  13. How duration affects the rate of electrolysis in a Voltaic Cell

    Variables:- Variable Type of variable How it will be controlled Time (s) Independent (The one you change) Values from 5 to 35 minutes will be used Mass of anode & cathode (g) Dependent (The one you measure) Electrodes will be measured after each time interval Current (A) Controlled Measure the current with the help on an ammeter Initial mass of cathode and anode (g) Controlled Weigh out the electrodes using top pan balance from the beginning of the experiment Charge on ion Controlled Use the same solution for all the trials. The charge on the copper ion should be 2+ since the copper 2+ is being converted to copper metal.

    • Word count: 2787
  14. DCP+CE Analysis of a Hydrogen Peroxide Solution

    Raw Data - 1st Titration on NaC2O4+H2SO4 with KMnO4 Trials Mass of the NaC2O4 (g�0.020g) Initial Reading of Burette (ml�0.075ml) Final Reading of Burette (ml�0.075ml) 1 0.300 0.00 23.000 2 0.310 0.00 24.200 3 0.310 0.00 26.500 4 0.300 0.00 22.550 5 0.340 0.00 26.500 6 0.350 0.00 25.600 Table 3. Raw Data - 2nd Titration on H2O2 + H2SO4 with KMnO4 Trials Initial Reading of Burette (ml�0.075ml) Final Reading of Burette (ml�0.075ml) 1 23.000 44.500 2 0.000 20.600 3 22.000 42.800 4 0.000 20.600 Table 4.

    • Word count: 2060
  15. pKa. When constant successive portions of Sodium Hydroxide are added to Acetic Acid; how do the changing amounts of Sodium hydroxide mixed with Acetic Acid in the conical flask affect the pKa of Acetic Acid?

    In a titration, base is gradually added until the acid reaches an endpoint or equivalence point. When the equivalence point is reached, the pH of the solution will change rapidly, because all the acid has reacted with the added base. A pH meter can be used to determine the pH of the acid throughout the titration, and can be used to determine the equivalence point. When carefully measured volumes of strong base are added to a solution of weak acid and the pH is noted, a graph can be drawn with pH on the y axis and the volume on the x axis.

    • Word count: 2396
  16. Finding the Equilibrium Constant for the Ester Formation of Ethyl ethanoate

    Below is a table with these values: Solution Average amount of NaOH (cm3) Random Error (�cm3) Reading Error (�cm3) Absolute Error (�cm3) 1 43.6 0.7 0.05 0.7 2 44.9 0.4 0.05 0.4 3 31.9 0.6 0.05 0.7 4 51.9 1.0 0.05 1.1 5 22.9 0.1 0.05 0.2 6 37.0 0.6 0.05 0.6 By taking an average there will be an inherent random error. This random error is equal to the (max titer - min titer)/2. Along with the random error is a reading error.

    • Word count: 2105
  17. In our research project, we will try to compare the qualitative contents of some energy drinks. These drinks will vary from international drinks to simple local energy drinks. To differentiate energy drinks form other drinks, such drinks can be compared t

    Taurine might be a "mild inhibitory neurotransmitter", some studies show it helps with excitable brain states, suggesting its addition to most energy drinks. Ginseng, an adaptogenic herb, is known to increase energy, relieve stress and increase memory. However, it does contain some anti-fatigue components. Right now it's suspected that ginseng helps stimulate the hypothalamic and pituitary glands, which then secrete something called adrenal corticotropic hormone. Ginseng is nothing that's naturally created in the body, so having it in drinks certainly won't hurt.

    • Word count: 2943
  18. The rate of reaction between sodium thiosulfate and hydrochloric acid

    * In the reaction between sodium thiosulfate solution and dilute hydrochloric acid, yellow sulfur (S(s)) is formed in the flask: 2HCl (aq) + Na2S2O3 (aq) --> 2NaCl (aq) + SO2 (g) + S (s) + H2O (l) [2] * In this experiment, I decide to alter the concentration of sodium thiosulfate by constantly increasing the concentration of sodium thiosulfate, the concentration of hydrochloric acid however is remained the same. My prediction is, the higher the concentration of sodium thiosulfate is, and the less time taken for the cross to stop being seen is. This should be because higher concentration of sodium thiosulfate will result the yellow sulfur precipitate to be formed more quickly.

    • Word count: 2480
  19. Effect of concentration on Nacl solution

    Ionic compounds1 form crystals in which anions and cations are held together with force of attraction. Ionic compounds are also known as salts mostly. They are usually hard and brittle. They are solid at room temperature and they have high melting and boiling points. They conduct electricity in solution because they dissociate into ions when dissolved in water, which are free to move. These ions carry the electrical charge from the anode to the cathode. Properties of salt solutions, which influence their electric conductance:2 The temperature of the solution. The magnitude of the charge on the ions.

    • Word count: 2280
  20. Chemistry extended essay - investigate the effect of 2-bromo-2-methyl propane concentration and temperature of the system on the rate of reaction of solvolysis of 2-bromo-2-methyl propane in 90% ethyl alcohol

    "Note2: the factor which determines the mechanisms employed is typically the nature of the substrate it self and not the particular nucleophile" "Note3: if the sum of the energy of the product is lower than the energy of the reactant the reaction is exothermic, and if the product have higher energy than the reactant the reaction is endothermic." 2- Elimination E1 (elimination unimolecular) And because t-butyl chloride acts as a Lewis acid (an electrophile) and combines with a nucleophile to give a substitution product, so the major product of the solvolysis of t-butyl chloride in water-acetone solvent is t-butyl alcohol.

    • Word count: 2855
  21. Enthalpy of Combustion of Alcohols Lab

    Enthalpies of formation are usually obtained directly from combustion experiments. ?Hc is measured in calories. ?H = mC?T IN THIS EXPERIMENT: We will burn measured masses of a series of alcohols, and calculate the amount of each alcohol burned. Assume that the energy produced is transferred to a measured volume of water, the temperature change of which is calculated. The enthalpy change involved in the combustion of one mole of each alcohol can then be calculated and compared. SAFETY DATA Butan-1-ol FLAMMABLE, Keep away from flames. HARMFUL Wash spillages away with water Ethanol HIGHLY FLAMMABLE, Keep away from flames.

    • Word count: 2377
  22. Factors Affecting Rate of Reaction

    The stopwatch recorded the time it took for the Alka-Seltzer tablet to react from the time the lead was put on, to when it came off 8. Appropriate observations were made from the reaction that followed 9. Repeated steps 1-8, using whole Alka-Seltzer tablets instead of powder 10. Calculated the data into rates of reaction using the formula g/s OBSERVATIONS AND CALCULATIONS Change in the Rate of Reaction: Surface Area SUBSTANCE MASS (grams) TEMPERATURE (�C) TIME (seconds) RATE OF REACTION (g/s)

    • Word count: 2089
  23. Lab Experiment : The change in mass when magnesium burns. (Finding the empirical formula of an oxide of magnesium)

    Smoke and white bumps on the metal. 7. Smoke. 8. Little smoke. 9. No smoke(white fluid material and residue on lid). 10. No further reaction. Raw Data: Initial mass of crucible with lid ( in grams) + 0.0001= 27.2160g Mass of magnesium inside crucible with the lid ( in grams) + 0.0001 =27.6096g Final mass of (MgO) inside crucible with lid in grams + 0.0001=27.82346g Mass of MgO inside crucible with lid in grams after �heating to constant mass`=27.8256g Processed Data: Percentage uncertainty= 0.04% 1.Mass of magnesium (in grams)

    • Word count: 2529
  24. Research Question Find the rate expression for a reaction between propanone and iodine

    � CH3COH2I(aq) + HI(aq) (Dilute sulfuric acid is used as a catalyst as the reaction is quite slow) Hypothesis The greater the concentration of the reactant the greater the rate of reaction. By increasing the concentration of the catalyst, rate of reaction should also increase due to the resulting lower activation energy. Procedure Materials * 1M solution of Propanone * 1M solution of H2SO4 * 0.0038M solution of Iodine * 0.0076M solution of Iodine * 0.0114M solution of Iodine * Distilled water Apparatus * Conical flask * 3 measuring cylinders (50ml, 25ml and 10ml) * White tile * Stopwatch Safety Precautions * Wear safety goggles to protect eyes, as the highly flammable propanone can cause irritation * Make sure the laboratory is ventilated to avoid inhalation of toxic gases i.e.

    • Word count: 2040
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Whilst Chemistry is a universal science, studying it at IB is quite different from other courses. The most distinctive difference is that it has considerably more breadth in the coverage of topics. The 11 topic core include: Quantitative Chemistry, Atomic Structure, Periodicity, Bonding, Energetics, Kinetics and Organic Chemistry.

The seven optional topics include modern analytical chemistry, human biochemistry, medicines and drugs, food chemistry, chemistry in industry and society, further organic chemistry and environmental chemistry. You'll be expected to become adept at practical laboratory work, data collection and manipulation, and build a strong scientific awareness. External assessment consists of three written papers, which you may find easier to face having accessed the Marked by Teachers collection of IB Chemistry essays. Internal assessment, which makes up 24% of the marks, consists of an interdisciplinary project, a variety of short and long-term practical investigations and some subject-specific projects.

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