Thermometric Titration
CHEMISTRY COURSEWORK (II) THERMOMETRIC TITRATION by Andrew McLorn Planning Normally we use an indicator when doing titration experiments, in this experiment we will not be using an indicator. Instead we will be monitoring the temperature of the solution. When an alkali is mixed with an acid heat is given out, this is called an exothermic reaction. The temperature goes up until the acid is neutralised and then no more heat is given out because the reaction is over. Adding more alkali causes the temperature to decrease. Apparatus .retort stand and clamp .burette .pipette .small beaker containing HCl .small beaker containing NaOH .funnel .polystyrene cup thermometer Method )collect apparatus 2)pipette 25cm3 of acid 3)put the acid in to the polystyrene cup 4)fill burette with NaOH 5)put thermometer in polystyrene cup and note temperature 6)add 5cm3 of NaOH, stir the solution and note temperature 7)keep adding NaOH at 5cm3 intervals, stir and note temperature between each addition of NaOH Displaying the Results Results should be displayed in a graph and a table like the one shown below: Safety The following safety precautions should be observed when carrying out this experiment: .assemble apparatusin the centre of an uncluttered bench .take care as acid is being used .wear goggles Conclusion As expected, the temperature of the solution increased
The order of the decomposition of hydrogen peroxide
The order of the decomposition of hydrogen peroxide Objectives: To show that the decomposition of hydrogen peroxide is a first order reaction Introduction: Refer to the lab manual Apparatus: Refer to the lab manual Chemicals: Refer to the lab manual Procedures: Refer to the lab manual Precautions: Refer to the lab manual Results: Time /min Final burette reading /cm3 Initial burette reading /cm3 Volume of KMn04 /cm3 0 41.20 0.80 30.40 5 25.20 .15 24.05 0 43.55 25.20 8.35 5 6.45 .60 4.85 20 28.30 6.45 1.85 25 37.35 28.30 9.05 30 44.40 37.35 7.05 Let Vo cm3 be the potassium permanganate solution required for the oxidation of hydrogen peroxide at the beginning of the reaction to, and Vt cm3 required after time t, the concentration of hydrogen peroxide at these times are proportional to Vo and Vt respectively t /min a, Vo /cm3 a-x, Vt /cm3 x, Vo-Vt /cm3 log a/(a-x) k = (2.303/t)[ log a/(a-x)] 0 30.40 30.40 0 0 / 5 30.40 24.05 6.35 0.102 0.0469 0 30.40 8.35 2.05 0.219 0.0505 5 30.40 4.85 5.55 0.311 0.0478 20 30.40 1.85 8.55 0.409 0.0471 25 30.40 9.05 21.35 0.526 0.0485 30 30.40 7.05 23.35 0.635 0.0487 bi. bii. biii. c. by bii. Reaction rate at t = 8mins = 0.0004(3)(82) - 0.0362(2)(8) + 1.4988 = 0.996 cm3min-1 Reaction rate at t = 12mins = 0.0004(3)(122) - 0.0362(2)(12) + 1.4988 =
Explain the need for primary and secondary standards in analysis
Ardit Cenalia Unit 19 | M1 Explain the need for primary and secondary standards in analysis What is primary standard? A primary standard is a solution of which a concentrated is made from a primary standard. I.E. the substance available in a sufficiently pure from which requires no determination of concentration. A primary standard is one that can be determined to a high level of precision, and reliability. For instance, a typical acid-base titration can be done to determine the concentration of an unknown HCl solution. When titrated against NaOH there will be some uncertainty because of the lack of reliability of the NaOH concentration. For example sodium chloride is an example of a primary standard. This is because it can be obtained very pure. What is a secondary standard solution? A secondary standard solution is a solution which must be standardised first against a primary standard and afterwards it will be stable enough for titrimetric work. Potassium permanganate is an example of a secondary standard. It has to be standardised first, but then it can be used for quantitative analysis, A primary standard substance will not always be used in standardisation; this is because primary standard is a reagent which is very pure, representative of the number of moles the substance contains and easily weighed. For example sodium chloride is used as a primary
How do Fireworks Work? Fireworks are made up of several components:
FIREWORKS Fireworks were first developed in China and used by the Chinese on any event (e.g. birth, death, wedding, new year). Some scholars say fireworks were developed in the Sui and Tang Dynasties (581-907), but others say that there were no fireworks until the Northern Song Dynasty (10th century). HOW DO FIREWORKS WORK? Fireworks are made up of several components: * Gunpowder - a mixture composing of: 75% Potassium Nitrate (KNO3), 15% Charcoal (Carbon), and 10% Sulphur. * Casing - Thick cardboard or paper rolled up into a tube. * A fuse - cotton twine coated with gunpowder. The gunpowder/fuel (which provides thrust for most fireworks) is tightly packed into the casing forming the propellant-core of the rocket in a length to diameter ratio of 7:1. e.g. 14cm long and 2cm in diameter. The fuse is lit by a match and then the fuse burns rapidly into the core of the rocket where it ignites the gunpowder walls of the interior core. Gunpowder contains potassium nitrate, which is the most important ingredient. This is because of the molecular structure of KNO3, which is made up one potassium atom (K), one nitrogen atom (N), and three oxygen atoms (O3). Since fire needs oxygen to burn the O3 is very important because it causes the KNO3 to release the oxygen, thus potassium nitrate oxidises the chemical reaction. This reaction is not impulsive and must be started by the
Aim : To investigate the percentage of CaCO3 in a sample of marble
Chemistry Practical Write-up Aim : To investigate the percentage of CaCO3 in a sample of marble Materials used : * Beaker * Conical Flask * Measuring Cylinder of 15 cc * Burette * Indicator * Clamp Stand * Pipette * Beam Balance * HNO3 of 2M concentration * NaOH of 2M concentration Procedure : * Crush the sample of marble in to small pieces, and take 1 gram of it in a beaker * Add excess of acid into the beaker, allow to react completely * Pipette 25 cc of the mixture into the conical flask * Add 2 drops of indicator (phenolphthalein) in the conical flask * Rinse the burette with NaOH, then fill it with the latter up to the 0 cc mark * Titrate the mixture with the base until color changes to purple. In the process, shake the conical flask thoroughly * Calculate the amount of base reacted * Repeat the titration again to improve accuracy. Data Collection : Burette reading (NaOH) / cc HNO3 + marble used (cc) Initial Final Used 0 9 9 25 0 8.8 8.8 25 0 8.5 8.5 25 Mass of marble used = 3 grams Amount of acid used to dissolve the marble, 100 cc = 0.1 dm3 Volume of mixture taken = 0.025 dm3 Mean volume of NaOH used = 18.76 cm3 = 0.01876 dm3 CaCO3(s) + 2HNO3(aq) Ca(NO3)2(aq) + H2O(l) + CO2(g) Mol of HNO3 used = 0.1 x 2M = 0.2 mol Molar ratio of NaOH ~ 0.01876 x 2 = 0.03752 mol Mol in 0.1 dm3 of NaOH = 0.03752 x 4 = 0.15008 mol Mol
Investigate the Properties of Ionic and Covalent substances
Title: To Investigate the Properties of Ionic and Covalent substances Introduction: Certain properties of compounds, such as polar and non- polar solvents, melting point and conductivity of electricity, can be used to distinguish between Ionic and Covalent substances. Aim: To determine whether common laboratory substances are ionic or covalent in nature. Apparatus/Materials: Sodium Chloride Test Tubes Sucrose Glass Rods Naphthalene Beaker (2- 100cm3) Copper (II) Sulfate Battery Calcium Carbonate Connecting wires Calcium Oxide Electrodes Spatulas Bunsen burner Tongs Method(1): Heating Substances Approximately two spatulas of sodium chloride was placed into a test tube and its contents were gently heated at first then heated strongly until no further change occurred. This was repeated with the other salts. Method(2): Solubility of Substances Two spatulas fall of sodium chloride was poured into breakers 1 with water and oe with ethanol. Solution was mixed and was held for conductivity test same was done for other salts. Method(3): Conductivity Electrodes were connected to connecting wires and
The argument that refugees have a negative effect on society has been a topic of great debate for many years, both in the UK and across many other countries.
The argument that refugees have a negative effect on society has been a topic of great debate for many years, both in the UK and across many other
Lipid Formation
Discuss the function and structure of triglycerides in a living organism. Triglycerides are known to have a complex structure and function. Their structure contains carbons, hydrogen's, a carboxyl group and a hydroxyl group. The triglycerides, which act mainly as energy stores in animal and plants, are a large important group of lipids. A triglyceride consists of one molecule of glycerol and three fatty acids. The following shows how the triglyceride is formed and it also shows the structure of a triglyceride: Looking at the diagram above only one glycerol is attached to (by dehydration synthesis) 3 fatty acids. The fatty acids determine the characteristics or properties of the fat. The bond formed between the -OHs of the glycerol and the -OHs of the fatty acid is an ester bond. Fatty acids are chains of hydrocarbons 4 - 22 carbons long with the carboxyl functional (acid) group at end. Each carbon within the chain has 2 spots for bonds with hydrogen and if each carbon has two hydrogen's the fatty acid is known to be a saturated fatty acid. Digestion breaks down triglycerides into glycerol and fatty acids. These products pass through the intestine walls, where they reassemble into triglycerides as they pass into the blood. The digestion of triglycerides is slower than the digestion of other food types, due to the structural formula, fatty acid and glycerol. This is known to
To identify these chemicals I will carry out two types of test: Flame test and chemical test.
Problem: you are provided with 3 unknown chemicals which are labelled A, B, C, D and E. Carry out appropriate test to identify the chemicals. Method: to identify these chemicals I will carry out two types of test: Flame test and chemical test. Flame test: * To carry out the flame test I will dip the metal wire in the roaring Bunsen flame. * Then I dipped the wire in hydrochloric acid * Next I placed it into the sample and then I placed it into the roaring Bunsen Flame * After I recorded the colour of the flame Safety: * I wore goggles to protect my eyes from acid (hydrochloric acid is corrosive) * When I was not using the Bunsen burner, I put it on safety flame * I also used small amounts of acid and have a safety mat Test for cat ion: Chemical Flame colour Cat ion A Yellow Na+ B Lilac K+ C Green Cu2+ Test for an ion: Substance Test observation Sodium chloride Add Dilute hydrochloric acid It fizzes and carbon dioxide gas is produced Copper carbonate Add Acidified silver nitrate White precipitate Potassium sulphate I added Acidified barium chloride solution White precipitate Evaluation: Flame test and chemical test tell us which chemicals are present. This is called a qualitative analysis. In industry, it is also very important to know how much of the chemical is present. The difference between my tests and the tests carried out in
