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International Baccalaureate: Chemistry

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  1. Investigate one factor affecting the rate of enzymatic decomposition of hydrogen peroxide by catalase.

    Take the time when potato is placed inside hydrogen peroxide. Stop the stopwatch when the babbles are came off up to the top of test tube. Controlled Variable - Controlled Variable How it is controlled Why must they controlled Volume of hydrogen peroxide 5ml of hydrogen peroxide will be used for potato Hydrogen peroxide should decompose into water and oxygen due to catalase. It is important to replenish it. Size of the test tube Will use identical test tubes The volume of oxygen measure is constant in order.

    • Word count: 711
  2. Aim: to determine the concentration of sodium hydroxide by titration potassium hydrogen phthalate

    = 0.00988 moles Conversion of amount of NaOH(ml to dm-3) Trial Amount of NaOH in dm-3 1 0.0246 2 0.0252 3 0.0250 Concentration of NaOH Trial Concentration of NaOH (mol dm-3)

    • Word count: 358
  3. Using Solubility Rules to Indentify Unknown Solutions

    The molar mass of a compound is the total mass of all of the elements in that compound. The mass of the elements can be found on the Periodic table as atomic mass. Eg molar mass for NaCl = 23 + 35.5 = 58.5g When a substance will not dissolve in water to form an aqueous solution it is said to be insoluble. A precipitation reaction occurs when two aqueous solutions are combined to form a solid in the solution. This solid is called a precipitate. In this experiment known aqueous solution were combined to investigate whether a precipitate could be formed.

    • Word count: 3402
  4. Using Hess's law to calculate enthalpy change

    Measure and record the maximum temperature obtained using the thermometer. Part B 1) Weigh 6.16g of MgSO4.7H20 to the nearest 0.01g on a filter paper, using the digital balance. 2) Weigh 41.85g of water to the nearest 0.01g into a polystyrene cup using the balance. 3) Measure the initial temperature of the measured amount of water using the thermometer and record this value. 4) Dissolve the MgSO4.7H20 in the water and record the temperature change associated with this process. Results: Mass of MgSO4 = 3.01g Mass of Mg SO4.7 H2O = 6.16g Mass of water in Part A = 45.00g Mass of water in Part B = 41.85g Part A Part B Initial

    • Word count: 911
  5. 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
  6. 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
  7. The purpose of the experiment is to determine the amount of CO2 present in a contained space. Using alka-seltzer tablets to control the amount of CO2, which will be an independent factor.

    Quickly cover the lid to the beaker with the foil. Wait fifteen seconds, using the stopwatch, and then measure the amount of CO2 in the beaker. - Repeat this process with only different amounts of distilled water. There will be five trials. One with 5ml, 10ml, 15ml, 20ml, and finally 25ml of water. - Then this entire process will be repeated five times to ensure precision and more accurate values and information. - To test the amount of CO2 in the beaker, add 40 drops of the bromythol blue liquid.

    • Word count: 634
  8. To calculate the percentage composition of the mixture of Na2CO3 + NaHCO3

    The cooling process was time consuming. 2) When the heating started, there were some fumes evolved. 3) In the middle of the process of heating some orange colour deposits could be seen in the tripod stand. 4) It was hard to keep the lid of the crucible partially open, as it was not balancing perfectly. 5) The crucible turned very hot, thus it was hard to place the crucible in the dessicator. 6) The vaseline wasn't very sticky, thus the lid of the dessicator wasn't very tight. 7) Once the crucible was placed inside the dessicator, it was difficult to keep the lid partially open as it was too hot to touch and one had to use holder.

    • Word count: 617
  9. Limiting Reagent Lab. Purpose To determine which compound was the limiting reagent in a reaction between lead (II) nitrate and potassium iodide (referred from the lab sheet) To determine the theoretical value of lead (II) iodide

    nitrate used instead of 1.0 grams of lead (II) nitrate Observations 1. Quantitative data Substance weighed Mass (� 0.05g) Lab apparatus Watch glass 20.80 Filter paper 1.35 Reactants KI and watch glass 21.60 Pb(NO3)2 and watch glass 21.90 Product Precipitate and filter paper 2.76 Table 1: Mass of apparatus and chemicals with apparatus 2. Qualitative data * Potassium iodide appeared as white crystals. * Lead nitrate appeared as white crystals. Shapes of each lead nitrate particles were irregular. * Both potassium iodide and lead nitrate dissolved in water.

    • Word count: 1208
  10. Separation of Amino Acids by Thin Layer Chromatogrpahy

    The X-value represents the numbers from the samples collected from the recordings of the samples. Table 2 (the recordings of the Y-values from both tests): Test 1 (cm) (Uncertainty� 1 cm): Test 2(cm) (Uncertainty� 1 cm): Y-value (cm): 4.2 4.3 The Results from the samples: Test 1: Sample 1 : 0.06 Sample 2: Sample 3: Sample 4 : Test 2: Sample 1: or Sample 2: Sample 3: Sample 4: 0.06 Here are the actual Rf-Values for each amino acids (theoretical value): Alanine - 0.38 Lecine - 0.73 Lysine - 0.14 Conclusion and Evaluation: Conclusion:

    • Word count: 506
  11. Analysis of Sweets. Is it possible to find any of the substances(Starch,Gelatin, Sucrose/Glucose) in any of the different candy samples?

    Put small pieces of the different samples of the candies into three watchglasses 3. Put small amounts of H2O into the three watchglasses 4. Put small amounts of iodide into the three different samples containing small amounts of H2O 5. If the samples turn black then Starch can found in the samples of Candy. 6. To Find if there is any gelatin in any of the three samples of candy, you first cut the three different samples of candy into small pieces 7. Put the three different samples into three different beakers 8.

    • Word count: 503
  12. The purpose of this Titration Analysis of ASA experiment was to use titration analysis techniques to determine the amount of ASA content contained of a standard pain-relief tablet.

    KHP (KHC8H4O4 (aq)): 204.2220 g/mol 2) NaOH (aq): 39.9971 g/mol 3) ASA (C9H8O4 (aq)): 180.1583 g/mol List of Uncertainties in the Lab: - Erlenmeyer Flask 0.8mL - Volumetric Flask: 0.8mL - Pipet: 0.04ml - Electronic Mass Scale: 0.01g - Burette: 0.05mL (Smallest measurement is 0.1mL, uncertainty of any analog scale measurement is half of the smallest unit of measurement, thus the uncertainty for the burette is 0.05mL) Pre-lab Calculation: - Mass Of KHP required to prepare 100.0mL of a 0.150 mol/L solution is: Post-lab Calculations: - Part 1: Standardization of sodium hydroxide solution(NaOH(aq))

    • Word count: 1424
  13. Ammonium Chloride Enthalpy Lab. Data Collection and Processing

    - (16 � 0.05))] / 0.07 � 0.0002 = - [(23.40 � 0.04%)(4.186)( -9 � 0.1)] / 0.07 � 0.28% = - [(23.40 � 0.04%)(4.186)(-9 � 1.1%)] / 0.07 � 0.28% = - [ (-881.57 � 1.14%) / 0.07 � 0.28% = -( -12593.86 � 1.42%) = 12593.86 J/mol � 178.83 J/mol Trial 2: Step 1: Calculate Moles of NH4Cl (Mass / Molar Mass) = (3.40 � 0.01 / 53.49) = (3.40 � 0.29% / 53.49) = 0.06 � 0.29% = 0.06 � 0.0002 moles Step 2: Calculate the heat (enthalpy)

    • Word count: 876
  14. 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
  15. 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.

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  16. Estimating Errors in Chemistry There are two types of error which occur in measurements

    They do not average out so repeating results does not help to eliminate systematic errors. They can occur due to a design or manufacturing fault, incorrect calibration of equipment or incorrect use of equipment. e.g if the top of the meniscus is read in a pipette or a measuring cylinder. Identifying and eliminating systematic errors is important for increasing accuracy. They can be reduced by using better equipment or improving practical technique. Accuracy Accuracy is how correctly a piece of apparatus measures regardless of precision. If a car is travelling at 55 kph and a police speed detector reads 55kph, it is accurate.

    • Word count: 794
  17. Oncology and Chemistry - oncology can be a highly rewarding medical field because of the bonds you make with patients who survive. Oncology and chemistry can be considered two things that have great chemistry and complement each other.

    Before you graduate high school, you need choose a post secondary school, which you would like and might be able to attend, with accredited pre-medicine courses. You then need to attain the proper GPA and educational requirements to get into that post secondary educational school and get your high school diploma. If you are accepted in the post secondary school of your choice, take courses related to the sciences, like biology, chemistry, or anatomy. When graduating from that post secondary school and get your, most likely, Bachelor's degree; take the MCAT to try to get into Medical School.

    • Word count: 867
  18. Xenon: The noble gas Xenon, as it may be found only in small amounts is a very unique element because of its physical properties.

    Then they began to heat the air up until it formed back into a gas. During this reheat the three main elements that form air start to separate from it. First Nitrogen separates and then Argon and finally Oxygen, but there are some trace amounts of elements still left within the air. One of these elements is Xenon. This process of separating elements is known as fractional distillation. This is how Ramsay and Travers were able to detect Xenon and some other gases within the air.

    • Word count: 740
  19. Examining the Solubility of Substances in Double Replacement Reactions (Final)

    + BaCl2(aq) ZnCl2(aq) + BaSO4(s) Net Ionic Equation: Ba2+(aq) + SO42-(aq) BaSO4(s) ZnSO4 - AgNO3 : Overall equation: ZnSO4(aq) + 2AgNO3(aq) Zn(NO3)2(aq) + Ag2SO4(s) Net Ionic Equation: 2Ag+(aq) + SO42-(aq) Ag2SO4(s) ZnSO4 - Pb(NO3)2 : Overall equation: ZnSO4(aq) + Pb(NO3)2(aq) Zn(NO3)2(aq) + PbSO4(s) Net Ionic Equation: Pb2+(aq) + SO42-(aq) PbSO4(s) ZnSO4 - NaCl : Overall equation: ZnSO4(aq) + 2NaCl(aq) ZnCl2(aq) + Na2SO4(aq) Net Ionic Equation: No reaction ZnSO4 - NaBr : Overall equation: ZnSO4(aq) + 2NaBr(aq) ZnBr2(aq) + Na2SO4(aq) Net Ionic Equation: No reaction ZnSO4 - CuSO4 : Overall equation: ZnSO4(aq) + CuSO4(aq) ZnSO4(aq) + CuSO4(aq) Net Ionic Equation: No reaction ZnSO4 - NaI : Overall equation: ZnSO4(aq)

    • Word count: 1638
  20. Rate of reaction of Magnesium with Hydrochloric acid

    1mol dm-3 Hydrochloric acid, 2mol dm-3 Hydrochloric acid, 1mol dm-3 Sulphuric acid. Dependent Variable: Gas produced as a result of the reaction measure over 10 second time period. Controlled: Temperature, Amount of Magnesium (and also surface area), Hydrochloric acid (1mol dm-3), Sulphuric acid (1mol dm-3), Hydrochloric acid (1mol dm-3). Apparatus and Chemicals: * Conical flask (100 cm3) * Rubber bung and delivery tube to connect conical flask to 100cm3 gas syringe * Measuring cylinders (100 cm3) * Clamp stand, boss and stand * Stop watch * Graph paper * Magnesium ribbon, cut into 3cm pieces and coiled * Hydrochloric acid, 1 mol dm-3 * Hydrochloric acid, 2 mol dm-3 * Sulphuric acid, 1 mol dm-3 Procedure 1.

    • Word count: 1453
  21. Experiment to measure the solubility of Calcium Hydroxide.

    2. Added about spatula of solid calcium hydroxide. 3. Stoppered the flask and shook well for on minute. 4. Left to stand for at least 24 hours. Ca(OH)2(s) + H2O(l) ==== Ca(OH)2( aq) 5. After 24hours took solution of Ca(OH)2 out and used thermometer to measure the temperature of it. 6. Made Filter Funnel lined with filter paper to keep extra Ca(OH)2 solid out and filtered saturated solution to a flask. 7. Used Pipet place 10cm3 of sample Ca(OH)2 solution in a beaker. 8. Dropped 2 drops methyl orange as indicator. The colour of Ca(OH)2 solution changed from colourless to yellow.

    • Word count: 842
  22. Our aim in this experiment to measure the heats of reaction for three related exothermic reactions and to verify Hesss Law of Heat Summation

    http://www.science.uwaterloo.ca/~cchieh/cact/c120/hess.html REACTION 1: NaOH(s)=Na(aq)+OH(aq) Data table1:table for the values of the reaction NaOH(s)=Na(aq)+OH(aq) time(sec) 0 30 60 90 120 150 temperature(�0,01)C� trial1 23 25 25 26 26 26 mass of NaOH=0,541(�0,0001)g,50(�0,1)ml water trial2 23 24,5 25 26 25,5 25 mass of NaOH=0,563(�0,0001)g,50(�0,1)ml water trial3 23 24 24,5 25 25,5 26 mass of NaOH=0,550(�0,0001)g,50(�0,1)ml water Graph1:the graph of temperature- time graph of NaOH(s)=Na(aq)+OH(aq) for trial1. Graph2:the graph of temperature- time graph of NaOH(s)=Na(aq)+OH(aq) for trial2. Graph3:the graph of temperature- time graph of NaOH(s)=Na(aq)+OH(aq) for trial3.

    • Word count: 1567
  23. Preparation of ear drops practical. Titration of NaHCO3

    When eardrops are administered they break up large compacted pieces of earwax into smaller manageable clumps. As mentioned the composition of eardrops vary depending on the specific ear problem. This experiment is based around the accuracy of a prepared eardrop. Method The method is devised into two separate sections: Preparation of eardrops 1. Weigh out 5 grams of NaHCO3 2. Add NaHCO3 to a volumetric flask then dissolve in 60ml of purified water. 3. Measure 30ml of glycerol using a pipette. 4. Add the glycerol to NaHCO3 solution 5. Make volume of NaHCO3 solution to 100ml by using purified water. Shake once mixed Titration 1. Take 5ml of eardrop and then add 20ml of water. 2.

    • Word count: 739
  24. Reactivity series for common metals experiment.

    Another table, but smaller, to record data. Procedure/Method 1. Get all required elements you are going to need, this elements are listed above. 2. Put the glass on top of the table of reactions. 3. Clean all metals, until they are shiny and clean. 4. Place 4 times the same metal on its corresponding column and different square; for all the metals(5). 5. Add carefully with the teat pipette one or two drops of the metal compound indicated directly onto the solid metal.

    • Word count: 1631
  25. Limiting Reagents. Aim: To investigate the reaction between sodium bicarbonate powder and ethanoic acid and discover the concept of limiting reagents.

    Large bubbles appear and the solution produces white foam. After a few minutes, bubbles stop appearing and solution in the conical flask turns clear. No heat or sound was observed. Processed data table Mass of NaHCO3/g Moles of NaHCO3 + 0.00005 mol Average Volume of CO2 (cm3) Moles of CO2 Theoretical Volume for CO2 0.30 0.0036 80 + 3 0.0033 91.67% 0.50 0.0060 131 + 3 0.0053 88.33% 0.70 0.0083 153 + 1.0* 0.0062 100.07% 0.90 0.011 152 + 2 0.0062 100.06% 1.10 0.013 154 + 1.0* 0.0063 99.77% 1.30 0.015 154 + 3 0.0063 99.77% *Because uncertainty starts with 1, therefore 2 significant numbers is necessary.

    • Word count: 641

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