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International Baccalaureate: Chemistry

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  1. Enthalpy of Combustion Lab Report

    4. Then the spirit lamp is lit and is placed on top of the beaker below the retort stand in order to maintain a steady position of the lamp underneath the calorimeter containing the distilled water. 5. The spirit lamp is allowed to burn for a fixed time period of one and a half minutes while the water in the calorimeter is continuously stirred using the stirring rod; after which the final temperature of the water in the calorimeter is measured with the help of the digital thermometer and is recorded as T2 (?0.1).

    • Word count: 2033
  2. Dissolved Oxygen in water

    is pumped into the water in order to increase its dissolved oxygen content. However, the bacteria that are added at the same time may be using some of that oxygen and thus will decrease the dissolved oxygen a little. In the chlorination tank, I believe that the dissolved oxygen content will be a little more than the air and bacteria tank because the chlorine will kill any microorganisms that are using the oxygen and hence the dissolved oxygen content will increase as it diffuses from the surrounding air.

    • Word count: 2804
  3. alkali titration

    1 * When two drops of phenolphthalein was added to the sodium hydroxide solution, the solution turned pink. * After adding about 20dm3 of oxalic acid solution, while swirling the conical flask gently, each drop of oxalic acid solution began to turn the pink solution slightly clear. * After about 20.6dm3 oxalic acid solution was added, the pink solution turned completely clear. 2 * Two drops of phenolphthalein was added to sodium hydroxide solution, producing a pink coloured solution. * After about 20dm3 of oxalic acid solution was added, each drop began turning the pink solution slightly clear.

    • Word count: 2392
  4. Calcium Carbonate and Hydrochloric Acid

    With increasing surface area, more surface area is available for the collisions to occur on. So when the surface area increases more collisions happen and therefore the reaction rate increases1. Materials > Hydrochloric acid HCl(l), > Calcium carbonate (marble chips) CaCO3(g) > Calcium carbonate (powder) CaCO3(g) > 250 ml3 flask > 50 ml3 measuring cylinder > Electronic scale > Stop clock > Cotton Variables Reaction time is the dependent variable, as it depends on the surface area of the marble chips. The surface area of calcium carbonate is the independent variable, as it does not depend in anything.

    • Word count: 2072
  5. hess's law

    - ??HfO (Reactants) The standard enthalpy of formation is equivalent to the sum of many separate processes included in the Born-Haber cycle of synthesis reactions. Germain Henri Hess (1802 - 1850) is important primarily for his thermochemical studies. Hess' Law states that the heat evolved or absorbed in a chemical process is the same whether the process takes place in one or in several steps. This is also known as the law of constant heat summation. Hypothesis: The reaction being investigated is summarized in the chemical equation below: CuSO4(s)

    • Word count: 2695
  6. Enthalpy Change of a Displacement Reaction

    The mass of cold water. m(water)=?(water)�V(water) =1g/mL�50mL =50g Absolute uncertainty=�1mL (Assume that the absolute uncertainty of ?(water) is negligible) % uncertainty=1/50 � 100%=2% b) The change of the temperature ?T is the temperature change after the warm water was added into the cold water. ?T=38.2?-20.2? =18? Absolute uncertainty= �0.5? + �0.5?=�1? % uncertainty=1?/18? � 100%=6% c) The heat absorbed by the cold water Q(cold water)=m�s�?T =50g�4.18J/g?�18? =3.8�103J =3.8kJ % uncertainty=2% + 6%=8% (Assume that the absolute uncertainty of the specific heat of water is negligible)

    • Word count: 2177
  7. Free essay

    Vitamin C in Fruit Juices

    EQUIPMENT & MATERIALS * * Safety goggles/Lab coat * Four Fruit juices (100 mL) * Vitamin C standard solution (1.0 g/mL) * Starch solution (1%) * Iodine solution * Hydrochloric acid (HCl) 1M * Distilled water * 50-mL burette * Burette * Retort Stand and Burette Clamp * 10ml Graduated pipette and pumpette * 25-mL Graduated cylinder * Two 125-mL conical flasks * Two 100-mL beaker PROCEDURE 1. A 10-mL graduated pipette was used to obtain 10.0 mL of the vitamin C standard solution, and placed in a flask.

    • Word count: 2006
  8. The chemistry of Alcohols

    + 2Na(s)--> CH3CH2O-Na+(s) +H2(g) Nuclear substitution reactions break the polar C-OH bond of ethanol. The Polar O-H bond is broken when an Ethanol is reduced by sodium. Hydrogen gas is slowly released, forming a solution of the product alkoxide ion RO- in ethanol. This forms the solid sodium ethoxide when evaporated. The general equation between an alcohol and sodium, forming an alkoxide and hydrogen gas is as follows: 2ROH(l) +2Na(s)-->2Na+RO-(s) + H2(g) 2)To 1 cm3 of ethanol in a clean dry test tube, add half a small spatula of PCl5(s).

    • Word count: 2338
  9. Analysis of the Nitrogen Content of Lawn Fertiliser

    Materials: * * 100 cm3 of 0.1 mol dm-3 NaOH * 100 cm3 of 0.1 mol dm-3 HCl * 1.5 grams of fertiliser * 250 cm3 volumetric flask * 3 � 250 cm3 conical flasks * 20 cm3 pipette * Burette and retort stand * 50 cm3 measuring cylinder * Bunsen burner, tripod, gauze mat * Mortar and pestle * Electronic balance * White tile, bench mat * Funnel * Spatula * Red Litmus paper * Methyl red indicator * Safety Measures: * Safety goggles must be worn at all times.

    • Word count: 2267
  10. Should we be recycling more alluminium in the future?

    It shows that the total usage increases more and more as the years go by, showing a straight trend. The amount of how much aluminium being made is normal; it is increasing rapidly, but not too fast. However, the amount of aluminium recycled is increasing extremely slowly. This could be because since it takes quite a lot of times for people to begin to recycle and how year after year people are getting more and more educated about it. Because aluminium is very resistant and soft, most vehicles such as cars, boats, trains, planes, and spacecrafts are made of aluminium.

    • Word count: 2599
  11. Determining and comparing the heats of combustions of alcohols

    Therefore, it has more bonds. So more energy will be given out when these bonds are broken since there are more bonds to break. We must also remember that the Oxygen atom in Alcohols is present with a single bond to the Carbon atom. This means Alcohols are already "partially oxidized" and some heat energy is absorbed in breaking Oxygen bonds during Alcohol combustion. However, the Heats of Formation for all the CO2 and H2O produced are much greater in magnitude than the absorbed energy related to Oxygen bonds, resulting in a net release of heat energy.

    • Word count: 2137
  12. IB Chemistry Lab Design - compare the effect of temperature on the concentrations of Vitamin C and Vitamin A in solution

    This investigation will compare the effects of high temperature on Vitamin A and Vitamin C solutions. http://chemmovies.unl.edu/chemistry/smallscale/SSGifs/SS054Ascorbic.gif The ascorbic acid enzyme gets denatured at high temperatures because the tertiary structure of the protein, which the enzyme is made up of, unravels, causing the active site of the enzyme to change in shape. This leads to the substrate being unable to fit into the active site, and we say that the enzyme is denatured. This denaturing can take place at extremes of pH too.The Vitamin A (retinol) gets oxidised because, at high temperatures, it reacts with oxygen in the air to form a carboxylic acid (retinoic acid).

    • Word count: 2082
  13. The purpose of this experiment is to determine the concentration of a solution of sodium hydroxide by titration against a standard solution of potassium hydrogen phthalate.

    0.09955M ± 0.00008M Burette solution (±0.1ml) 0.1M Phenolphthalein indicator 2 drops Calculation Table below shows the number of trials taken from the NaOH solution from the burette and the intial and final values of the solution titrated along with the volumes titrated No of Titration Trials (burette) Initial reading (±0.02ml) Final reading (±0.02ml) Volume (±0.02ml) 1 0.09 ml 25.70 ml 25.61 ml 2 0.1 ml 25.50 ml 25.40 ml 3 0.09 ml 25.70 ml 25.61 ml Volume of burette solution used for titration = Final reading – Initial Reading Mean volume of solution = Sum of the values of the volume/number of observations = 25.61+25.61+25.4/3 =25.54 ml (±0.02ml)

    • Word count: 2550
  14. PURPOSE To determine the amount of water of crystallization in one mole of a hydrated salt and its formula

    + 5H2O BACKGROUND The amount of water present in the hydrate is determined by heating the hydrated salt in a crucible and thereby measuring the difference between the mass of the salt before and after heating. APPARATUS 1 Ceramic crucible 1 Bunsen burner 1 Ring stand 1 Pipe -clay triangle 1 Tongs 1 Electronic balance (+ 0.01g) REAGENTS Hydrated copper sulphate SAFETY 1. Hot items look the same as cool items. Be sure to wait until glassware is cool before transferring it from place to place 2.

    • Word count: 2143
  15. AIM: To verify that mass-mass relationships hold by measuring the amount of NaCl produced.

    M HCl solution PROCEDURE: 1. I measured the mass of a clean dry 250 cm3 empty beaker to the nearest 0.01 gram. 2. I transferred the Na2CO3 to the beaker using a spatula weighed out 3 grams of it. I measured the mass of the beaker and Na2CO3 to the nearest 0.01 gram and recorded it. 3. I calculated the moles of HCl required to consume the Na2CO3 . 4. I added the acid to my beaker slowly, observing any chemical and physical changes that occur.

    • Word count: 2378
  16. The purpose of this lab was to calculate the heat of formation for magnesium oxide (MgO).

    When the magnesium oxide powder was added to the hydrochloric acid, there was no immediate reaction 2. When stirring with the temperature probe, the magnesium oxide slowly started to dissolve heating up as it went along 3. In the end, there were still some clumps in the solution but it had reached maximum temperature Calculations: Trial 1 Calculations for the heat of formation for Mg(S) +2HCl (aq) →MgCl2 (aq) +H2 (g) Table 3: Uncertainty Calculations Uncertainty Calculations Absolute Uncertainty Percent Uncertainty Initial temperature Final temperature 22.1°C ±0.2°C 27.4°C ±0.2°C âT = 5.3°C ± 0.4°C âT = = 7.54% Mass of HCl heated 100.00g ± 0.01g ±0.01g ±1.00% Total uncertainty of Q 7.54% + 1.00% = 8.54% Moles of magnesium(Mg)

    • Word count: 2206
  17. Organic lab. Comparison of alkanes and alkenes

    Therefore, combustion occurred, since the water vapour means that H2O and CO2 are produced as bi products. The combustion almost complete, but not quite, since the black smoke suggests that a small amout of noxious CO and carbon were also produced. When the lighted splint is applied to the basin full of hexane, the whole surface of the alcohol catches fire (combusts) and a big flame forms, which lasts circa 5 minutes. As the fire blazes, some black smoke rises from it, and the walls of the evaporing basin become first light brown, and then progessively a darker shade of brown.

    • Word count: 2623
  18. Determination of the % by volume of ethanoic acid in 100cm^3 of water

    of acid,Na=mass of the acid/molar mass of the acid mass of the acid,Ma=molar mass of the acid number of moles of the acid molar mass of the acid: Mr(C6H5COOKCOOH)=6(12.01)+5(1.01)+12.01+2(16.00)+39.10+12.01+2(16.00) +1.01 =205.24 Hence,the mass of the acid,Ma=0.0250 205.24 =5.131g to 3 decimal places Results Table: RESULTS mass/g uncertainty/g` mass of weighing bottle and acid 39.01 +/-0.01 mass of weighing bottle 33.88 +/-0.01 mass of acid 5.13 +/-0.02 Concentration of the acid,Ca=number of moles of the acid/volume of the acid =0.0250 1000/250.00 =0.100 Error propagation sources of error % error calculation mass of the acid =0.02/5.13 =0.4 volume of solution made in

    • Word count: 2311
  19. Aim: To estimate volumetrically the amount of Calcium carbonate present in the eggshell

    We took 10ml of HCl in the conical flask and added 2-drops of phenolphthalein indicator and then we titrated it by taking standardized solution of NaOH in the burette. The end point of the titration was again the same the colour change from colourless to (pink), we recorded the volume of NaOH consumed and then did the calculation to figure out the exact molarity of the HCl. Part C: (Amount of Calcium Carbonate present in the Egg-Shell) The experiment was done in three steps:- By removing the egg shell from the boiled egg, we collected the shell in a watch

    • Word count: 2176
  20. Chemistry lab reort-molar volume of hydrogen

    As time elapsed, the stream has diminished. The only mistake was that a small piece of magnesium was dropped into the beaker containing water. A stream of small bubbles was emitted from the piece of magnesium sunk to the bottom. No bubbles flew out of the burette and no obvious mistakes were made. Calculation The number of moles of hydrogen gas produced is calculated through the reaction that it undergoes: The molar volume of hydrogen gas at STP is calculated using the combined gas law: According to the combined gas law: The molar volume of hydrogen gas at STP is Theoretical value: Molar volume of hydrogen gas Percentage error 100% 4.02% Trial 2 Raw Data Table Mass of magnesium ()

    • Word count: 2259
  21. Investigating Factors that Affect the Rate of Reaction of the Decomposition of Hydrogen Peroxide (Only method and tables no calculations0

    Dependent Variable- The rate of reaction of the decomposition of hydrogen peroxide ? rate of reaction = . Research Question- it is needed to calculate the rate of reaction (kPa sec-1) of the decomposition of H2O2 to understand how different factors such as the change in concentration and the change in temperature of H2O2 affect the rate of reaction. Materials and Method- Materials: 0.5 M Yeast solution (the catalyst) - 15 mL 45 mL of 3 % H2O2 solution A thermometer A computer with LoggerPro Program. A Vernier computer interface A Vernier Gas Pressure Sensor A 1 liter beaker A match to light up the bunsen burner A tripod Two 10 mL test tubes Two 10 mL pipette

    • Word count: 2040
  22. Analysis of the Standard Enthalpy of Combustion for Alcohols

    The larger the alcohol molecule, the more bonds will be broken and formed, and therefore more heat will be produced. Using experiments, the standard enthalpy of combustion of an alcohol can be found, buy first finding the heat released during the reaction using the equation Heat=mass of water ×specific heat capacity of water ×rise in temperature of water Note: The specific heat capacity of water is 4.18 Jg-1°C-1. and then finding the number of moles of alcohol burnt, and dividing the heat by this number.

    • Word count: 2893

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