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International Baccalaureate: Chemistry
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Electrochemical cell lab Aim :- To find out the feasibility of a redox reaction by looking at the cell potential of the reaction .
-> Zn2+ (aq) + 2e- (aq) Cu2+ (aq) + 2e- (aq) -> Cu (s) Cu2+ (aq) + Zn(s) -> Cu(s) + Zn2+ (aq) Experiment 2 Cu(s) -> Cu2+ (aq)+ 2e- (aq) Ag+(aq) + e- (aq) -> Ag(s) Cu(s) + 2Ag+ (aq) -> Cu2+ (Aq) + 2Ag (s) Experiment 3 Zn(s) -> Zn2+ (aq) + 2e- (aq) Ag+ (aq)
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M CuSO4 * Vernier Labquest and Temperature Probe * Retort Stand * Utility clamp * One hole stopper * 25mL volumetric pipette * magnetic stirrer * stirring chip Procedures 1. Set up Vernier Labquest with a temperature probe. Under ?file sensors?-> ?data collection?, enter 3s/sample and length=750s 2. Place a Styrofoam cup into a 600mL beaker. Measure out 25.0ml of 1.0M CuSO4 using a volumetric pipette into the Styrofoam cup 3. Use a utility clamp and a retort clamp to suspend the temperature probe.
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Design -How does the surface area of Calcium carbonate (CaCO3) affect the rate of reaction with dilute hydrochloric acid (HCl)?
An acid reacts with a carbonate to give a chloride, water and carbon dioxide. Over time, the mass of calcium carbonate decreases while the volume of gas, carbon dioxide, increases. The more gas that is produced in the reaction, the faster the reaction is occurring. This can be measured by means of a graduated gas syringe. The reaction can be represented by the equation: CaCO3(s) + 2HCl(aq) CaCl2(aq) + H2O(l) + CO2(g) The results of the two reactions are plotted on the same axes of a graph of volume of CO2 produced against the time taken.
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________________ ________________ 1. Dependent Variable ________________ The dependent variable is the pressure exerted by the confined gas (Air) inside the syringe in KPa. ________________ ________________ ________________ 1. Controlled Variables ________________ - Temperature of the Confined Gas (Air) inside the syringe. ________________ - Mass of the Confined Gas (Air) ________________ - Size of the syringe and piston in which the Gas (Air) is confined. ________________ ________________ ________________ 1. Method ________________ ________________ 1. How to change the independent variable ________________ Applying force to the piston of the Syringe in order to decrease the Volume of the confined gas (Air)
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Investigation of reversible reactions at equilibrium - CuCl2 (s) was added to HCl , NaCl , H2SO4 respectively .
NaCl (s) When NaCl (s) is added to the solution, the color of the solution changes from cyan to green . The salt was required to be stirred for a while before it could be dissolved in the solution . When water was added to the solution , the color of the solution changed from green to the original color . The solution however did not appear to be transparent as the original solution , rather it was translucent / murky .
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The reaction can be represented by the equation: CaCO3(s) + 2HCl(aq) CaCl2(aq) + H2O(l) + CO2(g) The results of the two reactions are plotted on the same axes of a graph of volume of CO2 produced against the time taken. The gradient of the curves are used to judge the rate of the reaction; the steeper the slope, the faster is the reaction. The time taken to reach the end of reaction (curve to become horizontal) also indicates the speed of the reaction; the less reaction time needed, the faster is the reaction.
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Plan for an electrolysis experiment to determine the relationship between the current and the amount of metal deposited at the cathode.
The selected type of electrode and electrolyte are copper and 1.0M copper (ii) sulphate solution. HYPOTHESIS The amount of copper deposited at the cathode is directly proportional to the current. VARIABLES VARIABLES UNIT Independent variable: Current, I A (Ampere) Dependent variable: The amount of copper deposited at the cathode g (gram) Table 1 : the independent and dependent variables of the experiment CONTROLLED VARIABLES UNIT HOW TO CONTROL THE VARIABLES The size of copper electrode - Both copper electrodes physically has the same size and identical Concentration of copper (ii)
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The uncertainty in the HCl is given by the manufacturer of the measuring cylinder. 3. The uncertainty in the time is a rough estimate calculated by me trying to perfectly stop the stopwatch at 5 seconds three times in a row, and in all cases it was about 0.4 seconds reaction time. 4. The uncertainty in Total Volume of Na2S2O3 (aq) and H2O is found by adding the uncertainty in the volume of H2O and the uncertainty in the volume of Na2S2O3.
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If we don?t take excess of acid then the substance will not react completely with the acid and hence this will then lead to major inaccuracies in the experiment and the result of the experiment will be wrong , having large discrepancy. 1. Concentration of NaOH The NaOH concentration that will be used in the experiment will be prepared before performing the experiment whose concentration is known. In the second stage of titration, contrary to the first stage we do not use excess of NaOH.
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It can be argued that the water used for washing the utensils is not pure so if people eat food via that utensil, germs could enter their system. But as a safety measure our school canteen uses a disinfectant known as Surf Excel as obtained from the survey conducted by our ESS group. Hence further purification of the tap water is not really required. It can also be inferred from the readings above that after boiling the water it becomes more pure, but the boiling point of the
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The bottom and sides of the can were slightly wet due to condensation since the water added to it was quite cold. Calculations Trial 1 Moles of Ethanol = m/mr Moles of Ethanol = 1.85/46.08 = 0.0401 mol % uncertainty in mass = 0.02/1.85*100 = 1.1% % uncertainty in molar mass = 0% % uncertainty in moles = 1.1+0 = 1.1% % uncertainty to absolute uncertainty of moles = 1.1*0.0401/100 = 0.0004 ∴ Absolute uncertainty of moles = 0.0401 ±0.0004 mol Q = m*c* ΔT Q = 200.0*4.18*40.0 Q = 33440J = 33.44 KJ % uncertainty in volume =0.1/200.0*100 =
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0.5°C Final Temperature = 40 ± 0.5°C Time elapsed: 7 minutes To find the energy transferred to the water, we can use this equation: Energy = 4.18 x 100 x 13 = 5354 Joules Mass of ethanol ÷ Molar mass of ethanol ï 3.125 g ÷ 46.06844 g/mol ï 0.0678 moles Assuming that all the heat is transferred to water, the calculated enthalpy of combustion of ethanol is: = 80,147.49263 Joules/mol ï
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27.5 27.2 360 26 27 27 26.7 420 26 27 27 26.7 480 26 27 26.5 26.5 540 25.5 26.5 26.5 26.2 600 25.5 26.5 26.5 26.2 Uncertainty in Stopwatch = ± 0.05s Least count of Thermometer = 1oC Uncertainty in Thermometer = 0.5oC Volume of Acid Taken = 10 ml Volume of Base Taken = 10 ml
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360 29 29.5 31 29.8 420 29 29 30.5 29.5 480 28 29 30.5 29.2 540 27.5 28.5 30 28.7 600 27.5 28.5 29.5 28.5 Uncertainty in Stopwatch = ± 0.05s Least count of Thermometer = 1oC Uncertainty in Thermometer = 0.5oC Volume of Acid Taken = 5 ml Volume of Base Taken = 5 ml Least
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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)
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? MgxOy(s) AIM To determine the empirical formula of magnesium oxide HYPOTHESIS Empirical formula of Magnesium oxide is MgO. The simplest ratio of moles of magnesium atom to moles of oxygen atom is one to one (1:1). VARIABLE Type of variable Method to handle Independent variable 1. Magnesium ribbon Use a different magnesium ribbon in different experiment Dependent variable 1. Mass of magnesium oxide Calculate the mass of magnesium oxide using electronic balance Controlled variable 1. Mass of magnesium ribbon Use a same mass of magnesium in both experiment that is 0.3g APPARATUS AND MATERIALS 1. Magnesium ribbon, Mg 2.
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(salt) The theoretical mass of aspirin can be calculated by considering the relative atomic mass of its elements. The molecular weight calculation is as follows: (12.0107*9) + (1.00794*8) + (15.9994*4)=180.15742 g/mol Element Symbol Atomic Mass # of Atoms Mass Percentage Hydrogen H 1.00794 8 4.476% Carbon C 12.0107 9 60.001% Oxygen O 15.9994 4 35.523% Apparatus and Materials Apparatus Materials pH meter Aspirin tablet Burette Phenolphthalein indicator Conical Flask Bromothymol blue indicator Measuring cylinder 0.1M Sodium hydroxide, NaOH Retort stand Ethanol Procedure 1. Place an aspirin tablet in about 20ml of water and let stand for a few minutes.
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Coloured form Observe the coloured formation of the different oxidation state of vanadium Controlled variable 1. Element represented All of the complexes were containing vanadium APPARATUS AND MATERIALS 1. safety goggles 2. disposable gloves 3. conical flask, 100 ml 4. spatula 5. ammonium metavanadate 6. measuring cylinder , 25 ml 7. sulphuric acid, dilute, 1M 8. sulphuric acid, concentrated 9. 5 test tubes and holder 1. zinc powder, 2. Bunsen burner 3. filter funnel and paper 4. potassium manganate solution (VII), 0.002M 5.
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Aspirin causes many side effects, the most common is that it causes bleeding in the lining of the stomach. Exceeding the safe dosage can be fatal as the salicylic acid leads to acidosis due to a lowering of the hydrogen ion concentration in the blood. Aspirin?s structure is as follows: The reaction that will occur is the following: (CH3CO)2O + HOC6H4COOH CH3CO2C6H4CO2H + CH3COOH acetic anhydride salicylic acid acetylsalicylic acid acetic acid Apparatus 1. Salicylic acid 2. Acetic anhydride 3. Sulphuric acid 4. Water 5. Distilled water 6. Ethanol 7. Weighing boat 8. Digital balance 9. Two beakers 10. Measuring cylinder 11. Two filter papers 12. Two funnels 13. Two conical flasks 14. Stop watch 15. Safety mat 16.
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Aim: To investigate the reaction between sodium bicarbonate powder and ethanoic acid and discover the concept of limiting reagents.
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 Average Volume of CO2 (cm3) 0.30 80 + 3 0.50 131 + 3 0.70 153 + 1.0* 0.90 152 + 2 1.10 154 + 1.0* 1.30 154 + 3 *Because uncertainty starts with 1, therefore 2 significant numbers is necessary. Sample Calculations Calculating the average (83 + 78 + 78) cm3 3 = 79.66667 cm3 Rounded to two significant figures is 80 cm3 Calculating the uncertainty for my averages Calculated using residuals i.e.
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0.74 0.73 Leucine Looking at the data above, although the Rf values obtained differs slightly from the literature values, we could see that both values are only 0 to 0.02 apart. Both sets of values (obtained and literature) show that Leucine has the highest Rf value and lysine has the lowest value with aspartic acid in between. The actual amino acids were meant to be lysine aspartic acid and leucine. This means that my experiment was successful as I was able to identify all three amino acids correctly.
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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.
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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.
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Difference of Start and End Volume of Hydrogen - [Vâ- Vâ] (+/- 1 ml) 1 0.1 144 2 0.1 139 3 0.2 172 Average Volume of Hydrogen Gas: (144+139+172)/3 = 152ml. Processing of Results: 2Li(s) + 2Hâ0(l) 2LiOH(aq) + Hâ(g) No. of moles of Hâ = volume/(24x1000) = 152/24000 = 0.00633 No. of moles of Li = 2 x 0.00633 = 0.01266 (ratio of lithium to hydrogen is 2:1) Relative atomic mass of lithium = mass/number of moles = 0.1/0.001266 = 7.89 (3 sf)
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