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# International Baccalaureate: Chemistry

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• Peer Reviewed essays 1
1. ## Calculating the specific heat of a metal

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2. While the water was heating, the mass of a clean, dry 50-mL beaker was determined and recorded. Between 80 g and 120 g of lead shot was then added to the beaker and their combined mass was measured and recorded. 3. The lead shot was then transferred to a large, dry test tube. The utility clamp was used to suspend the test tube in the boiling water; the lead shot was below the level of the water in the beaker. The test tube was then left in the boiling for 10 minutes. 4. While the lead shot was heating, 100 mL of distilled water was measured I na graduated cylinder.

• Word count: 583
2. ## Hous Process for producing Sodium Carbonate

precipitates and is removed by filtration, and the solution is recycled to produce more sodium carbonate (Na2CO3). (Source 2.) The equation of Hou's process is: (1)NH3+H2O+CO2=NH4HCO3 (2)NH4HCO3+NaCl=NH4Cl+NaHCO3v (3)2NaHCO3=Na2CO3+H2O+CO2� NaCl (saturation) +NH3+H2O+CO2=NH4Cl+NaHCO3v 2NaHCO3==Na2CO3+H2O+CO2� Compare the Solvay process and Hou's process: (source 1.) The advantage of Hou's process is: Hou's process kept the advantage of the Solvay process, but increased the yield from 90% to 96%. The Product ammonium chloride (NH4Cl)

• Word count: 494
3. ## Structure and uses of nylon

* Superior colorfastness * Excellent abrasion resistance On the other hand, nylon 6 is easy to dye, more readily fades; it has a higher impact resistance, a more rapid moisture absorption, greater elasticity and elastic recovery. Benefit to society 1. Durable and stronger Nylon ropes are stronger and durable than ropes made from natural fiber, which explains why Nylon continues to gain immense popularity. Nylon has more uses than polyester, and is better for industrial use. 2. Flexibility and shock absorber Nylon is more efficient for industrial jobs where the material experience rapid or repeat stress.

• Word count: 595
4. ## How does density of a liquid affect the volume of its drop

� � Pipette pump � � Measuring cylinder (25cm3) � � Milk (30mL) � � Vegetable oil (30mL) � � Vinegar (30mL) � � Distilled water (30mL) � � Hydrochloric acid (30mL of 2moldm-3) � � Clamp stand Key Variables Independent Variable The densities of the liquid used:- � � Distilled Water- 1.00g/cm3 � � Vegetable Oil- 0.91g/cm3 � � Hydrochloric acid (2moldm-3)-1.19g/cm3 � � Vinegar (Ethanoic acid)- 1.01/cm3 � � Milk-1.03g/cm3 Dependent Variable The volume of a drop Controlled Variable Volume of each liquid used (20cm3)?

• Word count: 995
5. ## Testing for halide ions. The objective of the experiment was: Be able to identify halides using silver nitrate and ammonia.

and astatide (At-). Halide compounds such as KCl, KBr and KI can be tested with silver nitrate solution, AgNO3. The halogen will react with Ag+ and form a precipitate, with varying colour depending on the halogen. And, then by adding ammonia; the solution is acidified by adding dilute nitric acid. The nitric acid reacts with, and removes, other ions that might also give a confusing precipitate with silver nitrate. Procedure: * Potassium halides (potassium chloride, potassium bromide, potassium iodide) were placed into different three test tubes up to the height of 1ml. * Silver nitrate was added in all the three test tubes, containing potassium halides until a precipitate formed. * The colour of the three solutions was recorded.

• Word count: 830
6. ## Question: How the concentration of acid (HCl) can be determined by titrating it using base (NaOH)?

6- Take readings of PH value using the PH meter, after each drop. 7- When HCl color turns to blue, immediately stop adding NaOH, this indicates the neutralization point. 8- To be sure that HCl is neutralized add few drops of NaOH on HCl. 9- Repeat the experiment to obtain more accurate data. Data collection and processing: The table below shows the values of PH recorded over the five trials and indicates the neutralization point at a specific volume of NaOH added: (1.0) table shows the data collected during the trials Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 19.3 13.2 13.3 13.4 13.3 13.3 19.4 13.5 13.4 13.5 13.3 13.4

• Word count: 782
7. ## Chemistry report - The aim of this practical is to observe the difference in the reactivity between Mg and Ca when hot and cold water is added.

* Phenolphthalein * Beaker * Cold and hot water * Sandpaper * Test tubes with rack Procedure 1. The Magnesium was cleaned with sandpaper. 2. Two pieces of magnesium was put into two test tubes and two pieces of calcium was put into two test tubes. 3. Cold water was added into two test tubes one with calcium one with magnesium. 4. Two droplets of phenolphalein were added in each of the test tubes filled with cold water to observe the change in ph.

• Word count: 455
8. ## Determining the empirical formula of magnesium oxide lab

0.004114mol/0.004114mol=1 0.004375mol/0.004114mol=1.06 Therefore the empirical formula of the magnesium oxide is MgO Trial two: Magnesium Oxygen Mass/g 9.55g-9.42g=0.13g 10.02g-9.55=0.07g Moles /mol 0.13g/24.31gmol-1 =0.005348mol 0.07g/16.00gmol-1 =0.004375 Simplest ratio 0.005348mol/0.004375mol=1.22 0.004375mol/0.004375mol=1 Since multiplying the ratio by five gives the closest values to whole numbers, therefore the empirical formula of the oxide is Mg6O5. The third trial was not taken into account because the mass after combustion was not recorded. Uncertainty calculations: The uncertainties for masses in both tables will be: 0.01+0.01=0.02g Table one: Here are the calculations for the uncertainty for the number of moles of magnesium: 0.02g/.10g�100%=20% (the uncertainty for the molecular mass is taken as zero)

• Word count: 948
9. ## Food Chemistry Options Report - many different areas must be understood such as oxidative rancidity and how a food begins to rot, Antioxidants and how they can prevent such behavior, and Stereochemistry in foods to allow for the identification and better

One of the most common forms of Oxidative Rancidity is the way by which oxygen molecules react with fat structures. As this reaction occurs, longer chains of fatty acids are made to shorter ones because of the releases of hydroxide. Since these fats are typically less energized, an oxidation like this normally occurs with unsaturated fats since their one free radical makes them much easier to react with. It is important to realize the difference between oxidative rancidity and hydrolytic is the fact that oxidative rancidity is always caused by the reaction of oxygen molecules in the air with the fatty structures around them.

• Word count: 996
10. ## Equilibrium Lab - Restoring Balance. The solubility of iodine increases because the position of equilibrium has shifted towards the triiodide side of the reaction. Addition of the reactants causes an increase in the product which is directly related t

will cause the position of equilibrium to shift towards the products to compensate for the change. More products are a result of increased solubility of Ammonium Chloride with water when temperature is increased. Post Lab Questions 1. CoCl42- ions are present in this solution as they are blue colored and the color of the Cobalt Chloride solution was blue when we recorded the color and appearance of the solution. 2. Co(H2O)62+ ion was favored by the addition of water as it is pink colored and when we added water to the cobalt chloride solution, it became pink.

• Word count: 640
11. ## Lab #2 Water Hydration of Copper(II) Sulfate. Purpose- To determine the formula of the hydrate from the anhydrous compound.

3) Heat the crucible for about five minutes to fully sanitize it. 4) Stop heating and remove the crucible from the clay triangle onto the wire gauze and allow it to cool for about five minutes. 5) Place the crucible on the balance to find its mass. Record this data. 6) Add the copper (II) sulfate into the crucible using the spatula. 7) Place the crucible with the hydrate onto the clay triangle and begin to heat it for about five minutes. Record any observations. 8) Remove the crucible and transfer it to the wire gauze so that it can cool for two minutes.

• Word count: 714
12. ## Gas Law Stoichiometry Through Airbag Simulation. The purpose of this lab is to determine the correct ratio of baking soda and vinegar that leaves leaves no appreciable amount of either reactant leftover and yet fully inflates the bag without bursting.

Pour first trial amount of vinegar into bag and put it in one corner 5) Add baking soda and put it in another corner 6) Close the bag 7) Mix the two and shake the bag 8) Repeat with different amounts of vinegar Data- HC2H3O2 (mL) NaHCO3 (g) 25 4.83 30 4.84 69.1 4.84 62.2 4.84 Calculations- 1.0036(1.4)=n(.0821)(297) V= 1460 mL T=297 K P=1.0036 atm 1.405=24.38n n=.0575 CO2 .0575 moles CO2 x 84.01 grams baking soda ------------------------------------------------------ = 4.835 grams baking soda 1 mole Conclusions - We demonstrated that although it is possible to calculate the amount of solute needed to react it is not possible to determine the amount of solvent needed by using the combined gas law.

• Word count: 656
13. ## Graham's law. In this experiment the relationship between the molar mass of a gas and the speed with which it diffuses was to be assessed.

Based on this fact that no outside factors will influence the experiment we can directly plug our values into Graham's Law. Errors could have happened from gas escaping and can be prevented by more immediate actions. Purpose To demonstrate the relationship between the molar mass of a gas and the speed with which it diffuses. Materials In the hood: NH3 17 M, HCL 12M Cotton swabs Acetone Glass tube(60 cm in length) Meter stick Procedure First, three glass tubes were placed on a level table.

• Word count: 472
14. ## Ideal Gas Constant Lab

= .0362 grams = .0015 mol Mg = limiting reagent 24.13 g Mg Ratio between Mg and H2 is 1:1, therefore moles of H2 produced: .0015 mol H2 Calculating gas constant: PV= nRT Trial 1: 101.27( .032) = (.0015)R ( 298) = 7.25 J/mol * K Trial 2: 101.27(.0322) = (.0015)R (298) = 7.30 J/mol * K Trial 3: 101.27(.0323) = (.0015)R (298) = 7.32 J/mol * K (� .001 J/mol * K) Observations: Almost seconds after the eudiometer tube is inverted into the water, you can see the HCl acid sinking down through the water.

• Word count: 766
15. ## Universal Gas Constant Lab. Aim: To determine the universal constant for gases by collecting gas from a neutralization reaction and determining the volume and pressure of the gas and then the partial pressure of the gas formed.

= 45cm3 = 0.045dm3 Number of moles of H2(g) = (0.045/24) = 0.001875moles Ratio of Mg(s) to H2(g) = 1:1 => 0.001875 moles of Mg(s) => 0.001875 * 24.305 = 0.0455g � 0.04g Universal Gas Constant: P.V = n.r.T � r = (P.V)/(n.T) => R = (104.3 * 0.045)/(0.001875 * (24.5+273)) = 8.41 K-1 mol-1 => Percentage Error = {(8.41-8.31)/8.31} * 100 = 1.2% Qualitative Observations: * Colorless gas bubbles observed. * Concentration swirls observed. * Significant effervescence noticed close to the magnesium ribbon. * Colorless gas produced slowly then almost instantaneously the rate at which the colorless gas is being produced speeds up rapidly.

• Word count: 800
16. ## IB Chem lab. Once all twelve chemicals observations were recorded we started to experiment by mixing individual chemicals with other chemicals and recorded observations based on what we saw

To start with we had twelve individual chemicals to observe, on each chemical we check for states, (meaning liquid, solid or gas), color and odor if any. Once all twelve chemical's observations were recorded we started to experiment by mixing individual chemicals with other chemicals and recorded observations based on what we saw during the reacting and then the final state or the result.

• Word count: 412
17. ## 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
18. ## 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
19. ## 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
20. ## 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
21. ## 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
22. ## 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
23. ## 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
24. ## 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
25. ## 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
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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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