The Enthalpy of Neutralization
Enthalpy of Neutralization Data Collection Experiment 1 - The reaction between hydrochloric acid and sodium hydroxide. Table 1.1: Temperature of HCl and NaOH, separately and after mixing Reagent Temperature (°C) for Trial 1 Temperature (°C) for Trial 2 25cm3 of 2.00mol•dm-3HCl 21 ± 0.5 21 ± 0.5 25cm3 of 2.00mol•dm-3NaOH 21 ± 0.5 21 ± 0.5 Mixture of HCl and NaOH 34 ± 0.5 34 ± 0.5 Change in temperature (?T) -13 ± 1.0 -13 ± 1.0 Experiment 2 - The reaction between hydrochloric acid and potassium hydroxide. Table 2.1: Temperature of HCl and KOH, separately and after mixing Reagent Temperature (°C) for Trial 1 Temperature (°C) for Trial 2 25cm3 of 2.00mol•dm-3HCl 20 ± 0.5 21 ± 0.5 25cm3 of 2.00mol•dm-3 KOH 20 ± 0.5 21 ± 0.5 Mixture of HCl and KOH 32 ± 0.5 33 ± 0.5 Change in temperature (?T) -12 ± 1.0 -12 ± 1.0 Experiment 3 - The reaction between nitric acid and sodium hydroxide. Table 3.1: Temperature of HNO3 and NaOH, separately and after mixing Reagent Temperature (°C) for Trial 1 Temperature (°C) for Trial 2 25cm3 of 2.00mol•dm-3 HNO3 20.5 ± 0.5 21 ± 0.5 25cm3 of 2.00mol•dm-3NaOH 20.5 ± 0.5 21 ± 0.5 Mixture of HNO3 and NaOH 33 ± 0.5 34 ± 0.5 Change in temperature (?T) -12.5 ± 1.0 -13 ± 1.0 Experiment 4.1 - The reaction between sulfuric acid and 2.00mol•dm-3 sodium hydroxide. Table
Molar Heat combustion chemistry - investigate the effect of molar mass on the molar heat of combustion of adjacent members of a homologous alcohol series.
Aim To investigate the effect of molar mass on the molar heat of combustion of adjacent members of a homologous alcohol series. Introduction Chemists refer to the energy stored in a substance as the heat content or enthalpy of the substance. The heat of reaction is determined by the difference in the enthalpy between the reactants and products. The molar heat of combustion of a substance is the quantity of heat liberated when one mole of that substance is burnt completely in air. In the case of a hydrocarbon, the products are carbon dioxide and water. In this experiment you will determine the molar heat of combustion of methanol, ethanol, 1-propanol, 1-butanol; and 1-pentanol. Experimental Procedure Equipment * Electronic Balance ±0.01g * Measuring Cylinders ±1 mL * Aluminium Can * Cotton Wool * Theromometer ±0.5?C * Retort Stand and Clamp * Spirit Burner containing alcohol sample * Alcohols (methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol) Safety The alcohols are highly flammable. Always place the alcohol lamp on a tray to contain any accidental spillage of alcohol. Carefully use the cap of the alcohol lamp to smother its flame. Avoid skin contact with the chemicals. Lab coats and safety glasses must be worn at all times during the practical to ensure personal protection. Method . Design a data table to record the results of the experiment - this
Experiment - The Empirical Formula of Magnesium Oxide
The Empirical Formula of Magnesium Oxide Experimental Design Focus Question What is the empirical formula for magnesium oxide? Hypothesis The combustion of magnesium will generate data which can be used to calculate the empirical formula of magnesium oxide. Theory The following combination reaction was used in this experiment: Magnesium + Oxygen › Magnesium Oxide The Law of Conservation of Mass can be used to determine the amount of oxygen which has reacted with a given amount of magnesium in order to produce a measured amount of magnesium oxide. These masses can then be converted into moles in order to determine the simplest molar ratio and thus the empirical formula for magnesium oxide. Variables Variables identified Type of variable Treatment Amount of magnesium used Independent variable Different groups will use different masses. Masses will be small enough to ensure that the reaction can occur without requiring the lid to be lifted too often. Mass of magnesium oxide Dependent Variable The mass of this product will be measured after it has been observed that no further reaction will occur. Container used Controlled Variable A crucible with a lid will be used in order to allow the combustion in a closed environment, preventing the loss of magnesium oxide powder. Surface area of magnesium Controlled Variable Magnesium ribbon will be used in all
hess's law
LAB REPORT 12 - HESS'S LAW OF CONSTANT HEAT SUMMATION INTRODUCTION DESIGN Aim: To determine the molar enthalpy change of formation of hydrated copper sulphate from anhydrous copper sulphate by referring to Hess's Law of constant heat summation. General Background: The standard enthalpy of formation or "standard heat of formation" of a compound is the change of enthalpy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at 1 bar of pressure and the specified temperature, usually 298.15 K or 25 degrees Celsius). Its symbol is ?HfO. The standard enthalpy change of formation is measured in units of energy per amount of substance. Most are defined in kilojoules per mole, or kJ mol-1, but can also be measured in calories per mole, joules per mole or kilocalories per gram (any combination of these units conforming to the energy per mass or amount guideline). All elements in their standard states (oxygen gas, solid carbon in the form of graphite, etc.) have a standard enthalpy of formation of zero, as there is no change involved in their formation. The standard enthalpy change of formation is used in thermochemistry to find the standard enthalpy change of reaction. This is done by subtracting the sum of the standard enthalpies of formation of the reactants
Organic lab. Comparison of alkanes and alkenes
Vita Salvioni Guttmann Chemistry III HL 22-10-2012 Organic Lab Data Collection Part I – Alkanes . Volatility of methane, hexane, and paraffin Substance Methane Hexane Paraffin wax Observations Colorless gas, with a smell of sweet burnt alcohol. Clear, colorless liquid. Alcoholic smell, light but pungent. White, oily (waxy) solid. Very malleable, odorless. . Solubility of hexane and paraffin in water Substance Hexane + water Paraffin wax + water Observations Hexane when shaken with water does not dissolve. We can tell so because even though both liquids are clear and colorless, we can see a clear line which distinguishes one liquid from the other. The hexane floats right above the water, never mixing, and we can see the line of separation. Paraffin wax when shaken with water also does not dissolve. Even when finely ground, the solid pieces of wax float throughout the liquid and eventually deposit on the bottom of the test tube, never mixing with the water. . Combustibility of methane, hexane, and paraffin wax Substance Methane Hexane Paraffin wax Observations When the lighted splint is inserted in the test tube filled with methane, the flame quickly extinguishes itself, with a small spurt of black smoke. Right after, water vapour coats the walls of the test tube. Therefore, combustion occurred, since the water vapour means that H2O and CO2
Should we be recycling more alluminium in the future?
Should we be recycling more Aluminium in the future? Main Ideas Aluminium is identified for being the third most abundant element in the earth's crust. Chemically, aluminium is the 13th element on the periodic table, its symbol is Al, and its heat capacity is 25ºC. Aluminium is a silvery and flexible member of the poor metal group of chemical elements. Its melting point is 660.32ºC and boiling point is 2519ºC. Not only that, but it is also a soft and lightweight metal with idyllic properties, is a tremendously reactive metal and is conductive. When it is exposed to air, aluminium rapidly produces a transparent layer of Aluminium Oxide, which is even more resistant to corrosion - due to the occurrence of passivity. The ancient Greeks and Romans to heal wounds used aluminium salt. Aluminium has only become considerably used since the 1900's; even so, Sir Humphry Davy already established its existence in 1808. After Adolph Hitler's rise to power, Germany became the world leader in aluminium production. Further on, Joseph Needham discovered that the Chinese used aluminium, back in 1974. Nowadays, aluminium is regularly used and is part of our daily life, and is extremely useful in the industries of construction of many products. It is very important to the world economy. On the left there is a chart showing how much aluminium is being used, how much is being recycled and
Indicator Lab Report - investigating acid-base reactions
Data Collection Uncertainties Apparatus Uncertainty Significance Burette ± 0.05cm3 Insignificant. This uncertainty is very small, and so it is negligible. Pipette ± 0.06cm3 Insignificant. This uncertainty is very small, and so it is negligible. pH Probe ± 0.005 Insignificant. This uncertainty is very small, and so it is negligible. Below is a table showing the change in pH as an increasing amount of a base is added to the acid, thus changing pH. pH was monitored using a pH probe and the data was interpreted using Logger Pro. The thicker line represents the equivalence point. The concentrations of all substances was 0.5 molar. The amount of acid being titrated has a volume of 20 in all experiments. pH Change with Volume: Titrating HCl with NaOH Volume of Base ±0.05cm3 pH ±0.005 0.0 .13 2.0 .15 4.0 .30 6.0 2.14 8.0 2.28 0.0 2.73 2.0 2.81 4.0 3.06 6.0 3.04 8.0 3.11 20.0 3.11 22.0 3.21 24.0 3.24 26.0 3.26 28.0 3.27 30.0 3.31 pH Change with Volume: Titrating CH3COOH with NaOH Volume of Base ±0.05cm3 pH ±0.005 0.0 2.95 2.0 4.34 4.0 4.7 6.0 5.56 8.0 1.91 0.0 2.56 2.0 2.74 4.0 2.85 6.0 2.89 8.0 2.94 20.0 2.98 22.0 3.02 pH Change with Volume: Titrating HCl with NH3 Volume of Base ±0.05cm3 pH ±0.005 0.0 .15 2.0 .1 4.0 .1 6.0 .12 8.0 .15 0.0 .19 2.0 .23 4.0 .27 6.0 .32 8.0 .37
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.
Aim 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. Qualitative Data . Sodium hydroxide solution is colorless before titration 2. HCL is colorless before titration 3. The end result of the solution is slight pink 4. When the solution is off-shot the solution has a deep purple color 5. before reaching the endpoint the solution turns pink and then fades away as we swirl the conical flask 6. the color of phenolphthalein is colorless before titration 7. the color of phenolphthalein is slight pink after titration 8. a drop of the solution is left behind in the pipette 9. ideal color of the solution is fade pink Quantitative Data Table below shows the various volumes of chemicals that where used from their respected apparatus Apparatus / Chemicals used Reading taken from the apparatus Pipette solution (±0.06 cm3) 25 cm3 Burette solution (±0.02 cm3) 50 cm3 Phenolphthalein indicator 2 drops Standard C8H5O4K solution (±0.12 cm3) 250 cm3 Mean volume tittered 25.54cm3 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 No of Titration Trials (burette) Initial reading (±0.02ml) Final reading (±0.02ml) 1 0.09 ml 25.70 ml 2 0.1 ml
Lab Experiment : The change in mass when magnesium burns. (Finding the empirical formula of an oxide of magnesium)
Lab Experiment : The change in mass when magnesium burns. (Finding the empirical formula of an oxide of magnesium) Data Collection: Table showing the weight of the products recorded and processed. Trial run 2 3 4 5 Mass of crucible + lid (± 0.0001g) 27.2160 24.1874 32.9232 27.2815 32.9220 27.6400 Mass of Crucible + lid+ magnesium (± 0.0001g) 27.6096 24.5431 33.1472 27.6068 33.1552 27.9850 Mass of magnesium1. (± 0.0001g) 0.3936 0.3557 0.2240 0.3253 0.2332 0.3450 Mass of crucible + lid + magnesium oxide before heating to constant mass (± 0.0001g) 27.8326 No data 33.2711 No data 33.2811 No data Mass of crucible + lid + magnesium oxide after heating to constant mass (± 0.0001g) 27.8256 24.7389 33.2605 27.685 33.2725 28.2125 Mass of magnesium oxide (± 0.0001g) 0.6096 0.5515 0.3373 0.4035 0.3126 0.5725 Mass of oxygen combined with magnesium2. (± 0.0001g) 0.2167 0.1958 0.1133 0.0782 0.1296 0.2775 .The mass of magnesium ribbon = The mass of the crucible, lid and magnesium- mass of the crucible and lid. 2. Mass of oxygen = mass of magnesium oxide, crucible, lid - mass of magnesium, crucible, lid. Trail run: Observations: (Observations are made by lifting the lid after every 2 minutes) . Nothing. 2. Nothing but crucible glows red at the bottom. 3. White smoke . 4. Flame inside and lots of
The rate of reaction between sodium thiosulfate and hydrochloric acid
DESIGN * Research question: Does the change in concentration of sodium thiosulfate and the fixed concentration of hydrochloric acid result a change in time taken for the yellow sulfur precipitate to form, thus lead to a change in time taken for the cross to disappear and the rate of reaction? * Variables: * Independent variable: The concentration of sodium thiosulfate / M. * Dependent variable: The time taken for the cross to disappear / second. * Controlled variables: * The concentration of hydrochloric acid / M. * The temperature in each conical (Erlenmeyer) flask prior to every reaction / oC. * The absence of unnecessary substances or ions. * The angle to view the cross. * Prediction: * For many reactions involving liquids or gases, increasing the concentration of the reactants increases the rate of reaction. In order for any reaction to happen, particles must first collide. This is true whether both particles are in solution, or whether one is in solution and the other a solid. If the concentration is higher, the chances of collision are greater [1]. * 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