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International Baccalaureate: Chemistry

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  1. Aim: To study and investigate the effect of temperature on the rate of the reaction between sodium thiosulphate and hydrochloric acid.

    The rate of a chemical reaction depends on a number of factors. 1. Size of particles 2. Concentration 3. Temperature 4. Addition of a catalyst 5. Pressure of a gaseous reactant During the experiment, as we increase the temperature the average kinetic energy of the particles increase, resulting in a larger number of particles having activation energy. This in turn results in more effective collisions, increasing the speed of reaction. The reaction between sodium thiosulphate and hydrochloric acid proceeds to the following chemical equation: Na2S2O3(aq) + 2HCl(aq) ? 2NaCl(aq) + SO2(aq) + H2O(l) + S(s) This equation can also be represented in the ionic-equation form in the following manner: S2O32- + 2H+ ?

    • Word count: 1613
  2. Practical de quimica Structure and Bonding

    Part 5: Polarity of the liquids: As water conducts electricity, it should have some type of charge that will make it polar. In the case of the two organic compounds I don't think they are polar because they don't conduct electricity Results: Part 1: Solubility in liquids Solutes with Water Substance Observations Calcium Chloride Dissolved instantly, some bubbles appeared, an homogeneous colourless mixture was produced Graphite No dissolution, graphite ended on the bottom of the test tube. Iodine No dissolution, iodine went to the bottom of the beaker, water became pale yellow.

    • Word count: 1599
  3. Determination of the molar mass of Magnesium from the reaction of magnesium and hydrochloric acid.

    It varies according to the change for the magnesium used. * The controlled variables are the pressure and temperature in the room. Methods used 50 mm of magnesium ribbon was taken and weighed. Then 10 cm3 of HCl was poured into the eudiometer. Then water was carefully filled above the HCl in the eudiometer. Here water and HCl should not mix with each other. Then the magnesium ribbon was tied around a piece of copper wire on a rubber stopper. This rubber stopper with magnesium tied to it was used to close the eudiometer.

    • Word count: 1094
  4. Equilibrium Changes

    + SCN-(aq) FeSCN2+ 1. Variables Chart Independent variable The variable I will be manipulating is concentrations of the FSCN2+ (ironthiocyanate). Dependent variable(s) Position of equilibrium shown through equilibrium constant Kc. Control Variables - the variables that must be kept constant during the experiment How variables affect experiment How the method compensates for experiment Metal ions Without the reactants including metal ions, the solution would be colourless and thus there would be no way of measuring absorbency and thus of finding concentration.

    • Word count: 480
  5. Greenhouse Gas Lab

    Roughly 35% is emitted as light leaving 65% as heat energy.1 Therefore, the bulb emits 0.65x720=468 J or 0.468 kJ of heat energy. By filling the container to the brim with water, we used a measuring cylinder to measure the volume of the water which was to be: 992mL The theoretical specific heat capacity2 of methane was found to be 2.226J/g.C The table in the next page shows temperature readings in degrees Celsius of a methane sample collected in the closed container that was heated by this bulb over a period of 32 minutes.

    • Word count: 1437
  6. Investigating the effect of different liquid densities on the time taken to release 25 ml of alcohols

    * 125 ml propan-1-ol CH3(CH2)2OH 98%. * 125 ml butan-1-ol CH3(CH2)3OH 99%. * 125 ml octan-1-ol CH3(CH2)7OH 94%. * Thermometer (Uncertainty: � 0.0500 oC). * 5 x funnels. * 50 ml conical flask. * Casio stop watch (Uncertainty: � 0.0100 seconds). * Distilled water. * Risk assessment: * The procedure uses poisonous alcohols. Notably, suggested by Department of Chemistry - Imperial College London (2006) [2], less than 2 teaspoons (2 ml) of methanol can cause blindness, and 2 table spoons (30 ml) can cause death. This toxicity is mainly due to it being converted in the body to formic acid and formaldehyde, which first attack the cells in the retina, then the other vital organs.

    • Word count: 1966
  7. 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
  8. Design: Investigating the boiling point different alcohols

    * Method: * Apparatus: * 20 ml methanol CH3OH 99.5%. * 20 ml ethanol C2H5OH 95.0%. * 20 ml propan-1-ol C3H7OH 98%. * 20 ml butan-1-ol C4H9OH 99%. * 20 ml octan-1-ol C8H17OH 94%. * 3 x Pyrex test tubes. * A Bunsen burner. * A tripod. * Metal thermometer (Uncertainty: � 0.05 oC). * 50 ml burette (Uncertainty: � 0.500 ml). * A funnel. * A marker pen. * 2 x Retort stands. * 2 x clamps and bosses. * Risk assessment: * The procedure uses poisonous and highly flammable alcohols. Notably, suggested by Department of Chemistry - Imperial College London (2006)

    • Word count: 789
  9. Question: What is the relationship between pressure and temperature of a gas filled container with constant volume and number of moles?

    Click on weblink 3.2 the simulation on the right will appear. In this simulation one can set the parameters as per desire. For this experiment we need to set the volume and number of moles constant. Three trials are done for accuracy. For the first trial, we need to set the volume constant. The volume will remain set to the default value. Then pump 100 heavy species particle in the container and keep them the same until the next trial. The temperature will automatically go to 300K, remove heat to lower the temperature to 150K.

    • Word count: 1170
  10. We measured the change of temperature of two reactions to determine the enthalpy change of the third. We first theoretically calculated the enthalpy and then performed experiments.

    (-286 - (-230) = 56 Reaction 2:NaOH + NH4OH ==> NH3 + H2O Net ionic equation: NH4+ + OH- ==> NH3 + H2O Theoretical H for reaction 2: -366 - (-362) = -4 Reaction 3:HCL + NH3 ==> NH4Cl Net ionic equation: NH3 + H+ + Cl- ==> NH4+ + Cl- Theoretical H for reaction 3: -247-(-299)=52 Therefore according to Hess's law 2 reactions are added to get the H of third R3= R1 + R2 52= 56 + -4 Further calculations:

    • Word count: 571
  11. Investigation on solubility of different chemicals

    Materials: Top hand balance(1) Measuring cylinder 50cm3 (2, 1 per two chemicals [will wash after first use]) Measuring cylinder 10cm3 (1) Spatula (1) Calcium carbonate Calcium Sulphate Sugar Sodium Chloride Glass stirring rod (1) Notebook Data table Pencil, ruler, eraser Method: First my partner and I will collect all of our materials needed. (Listed above) Then we will select only one chemical to investigate first, and take 1cm3 of the chemical and place it into a 10cm3 measuring cylinder. Next, We will fill the 50cm3 measuring cylinder with 25cm3 of water After that, we will place the 1cm3 of our chosen chemical (already collected in step 2)

    • Word count: 961
  12. Research Question Will increasing the temperature (C) of the rennin enzyme affect the rate of reaction (seconds) at which Pauls full cream milk solidifies?

    [1] Contrary, decreasing the temperature would slow down the speed of particle collision so therefore the rate of reaction will also decrease. In this experiment, the rate of the reaction of rennin and milk will be tested. The temperature of rennin will vary from 25�C, 30�C; 35�C; 40�C; 45�C and the rate (time) at which the rennin causes the milk to solidify will be recorded as results. As temperature is a important factor for this experiment, experiment will be carried out at standard lab conditions and with a constant 25�C air temperature.

    • Word count: 1510
  13. Research Question By measuring the pH value of the acetic acid using a pH meter at standard lab conditions, will increasing the concentration of the acid affect its experimental determined Ka and therefore its calculated pKa?

    [1] pKa = -log Ka The pKa values of weaker acids will be larger than the values for stronger acids. Therefore the higher the pKa number is the weaker the acid. The concentration of an acid affects the Ka value and therefore the pKa value for a high molarity of any solution will attain a lower pH. With references to Ka, as the molarity of the solution increases the value of Ka decreases and the smaller Ka is the bigger pKa is.

    • Word count: 1422
  14. Factors Affecting Reaction Rates

    Equipments: Test Tubes Graduated Cylinder Different pieces of zinc (pieces granulated and powder) Water bath at 60? C Chemicals: 6M HCL 3M HCL 1M HCL 0.1M HCL Procedure: We experiment with four different concentrations of HCL. Firstly, we put the different concentration of HCL in four different tubes. In each tube we put a piece of zinc and observe what happens. Then we have 1M HCL in three different tubes. In one tube we put a piece of zinc, granulated in another one and in the third tube powdered zinc. After putting these in the three tubes we observe the changes.

    • Word count: 621
  15. Using Redox Titration to Analyze the Oxidizing Strength of Bleach Lab

    + 5 I- (aq) + 6 H+ (aq) 3 I2 (aq) + 3 H20 (l) 2 S203 2- (aq) + I2 (aq) 2 I- (aq) + S406 2- (aq) The ratio of the Iodate to the Iodine is 1:3 And the ratio of the Thiosulfate to the Iodine is 1:2 Therefore, the ratio of the Thiosulfate to KIO3 is 6:1 In order to find moles of Thiosulfate, one must multiply the moles of KIO3(found earlier) by 6 = 0.00005 moles � 6 = 0.0003 moles of Thiosulfate In order to find the concentration of Thiosulfate, one must divide the number of moles by the volume from the average

    • Word count: 1152
  16. Water of crystallization of BaCl2.xH2O

    The time for the crucible to cool after each time being heat Leave the crucible on the wire gauze for approximately 2 minutes after heating. The heat energy given to the hydrated BaCl2 Leave the air hole half open for 5 minutes then open the air hole to heat the crucible strongly with the blue flame. Apparatus: _ Bunsen burner _ Digital balance _ Tongs _ Crucible with lid _ Spatula _ Tripod _ Lighter _ Clay triangle _ Wire gauze Material: _ Crystallized barium chloride Procedure: 1.

    • Word count: 1860
  17. Testing antacids. The purpose of this investigation is to test different antacids mild base that can neutralize acid - for their effectiveness in neutralizing stomach acids, to see if all antacid tablets are equally effective, and to learn the way of

    Maalox 1.286g 0.200g 42 drops 2.8 ml 294 drops 14 ml/g 378 drops 18.004 ml Gaviscon 1.567g 0.200g 26 drops 1.5 ml 130 drops 6.5 ml/g 204 drops 10.1855 ml It is stated that pH of a normal stomach is about 1.5 which is very acidic. However, if the concentrations of acid in stomach are too high, it would cause great pain. A solution would be taking medication that contains an antacid, a mild base that can neutralize acid. With approximate mass of tablet of 0.200grams, it is to be mixed with water and thymol blue indicator which would change color at the pH level of around 2.

    • Word count: 1004
  18. 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
  19. Dissolving and Energy Changing

    We learn new things about endothermic and exothermic reactions and be acquainted with lab more. However during the experiment, there are few flaws groups keep making.

    • Word count: 257
  20. Chemistry Equilibrium Lab

    Volume of Water in a cylinder B (mL � 0.1 mL) 0 10.0 5.0 1 9.7 5.3 2 9.4 5.5 3 9.2 5.8 4 9.0 6.1 5 8.8 6.2 6 8.7 6.3 7 8.5 6.4 8 8.4 6.6 9 8.3 6.7 10 8.2 6.8 11 8.1 7.0 12 7.9 7.1 13 7.8 7.2 14 7.7 7.3 15 7.6 7.4 16 7.5 7.5 17 7.5 7.5 18 7.5 7.5 19 7.5 7.5 Table 3. Reaching equilibrium in 10mL of water in cylinder A and B with the different radius straw with 10mL of water Number of Transfers Volume of Water in a cylinder A (mL � 0.1 mL)

    • Word count: 1782
  21. Determining the Formula of an Unknown Hydrate

    + (1x 32.065) + (4x 16) = 24.31 + 32.065 + 64 = 120.275 g/mol Calculating Moles of Substance Mole = Mass/Molar Mass Mole of anhydrate Epsom salts Mass= 2.01 Molar Mass= 120.375 Mole= 2.01/120.375 = 0.0167 mol Calculating Water to Salt Ratio of Epsom Salts Moles of H2O Moles of Epsom salts = 0.111 0.0167 = 6.64 = 7 Calculating uncertainties of the moles of Epsom salt Uncertainty of Mass Molar Mass = 0.002 120.375 = 0.0002 Calculating Percent Error of Water to Salt ratio of Epsom salt Expected- Observed Expected = 7- 6.61360925671311 x 100 7 = 5.519867761241 = 5.51% Calculating Percent Error of Water to Salt ratio of Copper (II)

    • Word count: 854
  22. Determining the effect of the concentration of HCL over the rate of the reaction between Magnesium and Hydrochloric acid

    * Cut the Mg ribbon into three different lengths of 1, 2 and 3cm. We will use different lengths of Mg to make more accurate the experiment as we will have the same three lengths for both of the concentrations used. * Clean the Mg ribbon with the sandpaper to remove any oxides * Prepare the chronometer, put the Mg ribbon inside the conical flask and put the cork. Start the chronometer * After the reaction has ended, record the volume of gas produced and the time taken to produce it.

    • Word count: 1248
  23. 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
  24. Le Chatelier Lab

    Right from the first drop, the solution turns Dark Red C1 a) Place 10 drops of 0.001 mol dm-3 FeCl3 b)Add enough KSCN to see a colour change c)Add enough KCl to see another colour change a) Clear Colurless Solution (No Change) b) after 2 drops it fully turns Dark Red c)after 7 drops, it turns Light Orange D1 a) Place 10 drops of 0.001 mol dm-3 FeCl3 b)Add enough KSCN to see a colour change c)Add 1 or 2 drops of 0.1 mol dm-3 FeCl3 (which is 100 times stronger than the 0.001 mol dm-3 FeCl3)

    • Word count: 812
  25. im To determine the relative molecular mass of chloroacetic acid ClCH2COOH

    = concentration (c) * volume (v) = (2.08 * 10-2) (0.10) = 2.1 * 10-3 moles of sodium hydroxide reacted 2. Number of moles of chloroacetic acid reacted Chloroacetic acid (ClCH2COOH) reacts with sodium hydroxide (NaOH) to produce sodium chloroacetate (CClH2COONa) and water (H2O) according to the following equation: ClCH2COOH (aq) + NaOH (aq) �CClH2COONa (aq) + H2O (l) From the equation we see that: 1 mole of ClCH2COOH � 1 mole of NaOH x � 2.1 * 10-3 mole NaOH Number of moles of ClCH2COOH reacted = x = 1 * 2.1 * 10-3 = 2.1 * 10-3 mol 1 3.

    • Word count: 872

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