Chemical Reactions Lab Report

Half a gram of magnesium was measured on a scale and 50 millimeters of 2M hydrochloric acid in a small graduated cylinder. The HCl was then added to the Erlenmeyer flask. The tube was secured to the Erlenmeyer flask and was ran under the large graduated cylinder in the tub. With the rubber stopper off and other equipment ready, the magnesium was added to the Erlenmeyer flask. Quickly, the rubber stopper was placed on top of the flask to ensure that no gas escapes.

Experiment 2 focused on finding the enthalpy of solution of magnesium chloride. Testing the enthalpy of solution started with measuring out 10 mL of deionized water in a graduated cylinder for three separate trials, each trial having a different mass of magnesium chloride. The water was then poured into a well of a Styrofoam calorimeter then the initial temperature of water was taken using a temperature probe and the LoggerPro programming. A measured amount of magnesium chloride was placed in the same well as the water in the calorimeter,

About 80 mL of HCl was obtained and mixed with phenolphthalein. Using a LabQuest unit and Gas Pressure Sensor kit, the HCl mixture was added to the flask with the magnesium ribbon and allowed to react. When reaction was complete, the change of temperature and gas was recorded. This procedure was repeated for different masses of magnesium ribbon (masses found on page 89 of the lab manual). After the completed procedure, moles of H₂ produced in each trial were calculated. (The actual procedure can be found on pages 87-89 of the lab manual)

Because it is dangerous to burn magnesium, it is not possible to directly record heat change. Our lab team suggests an indirect way of determining the heat of combustion for magnesium. To accomplish this, we need to perform two separate trials. One uses a solid (powder) version of MgO, while the other uses Mg ribbon. With the results from these, we can use Hess’ Law to determine q=∆H. This provides both a safe and successful way of indirectly determining the heat of combustion for magnesium.

A chemical reaction is a process that involves change of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction. The key concepts of a chemical reaction are:

1. Which reactants used in this experiment are flammable? Discuss the safety precautions that are necessary when working with flammable materials in the lab?

For the first trial, after .398 grams of magnesium were mixed with .251 grams of oxygen, the result yielded .649 grams of magnesium oxide. In the second trial, after .404 grams of magnesium were mixed with .132 grams of oxygen, the result yielded .536 grams of magnesium oxide. In the third trial, after .406 grams of magnesium were mixed with .702 grams of oxygen, the result yielded 1.108 grams of magnesium oxide. All three of the trials yielded different results in the data table; but, there were only two different empirical formulas, percent compositions and mole ratios for each of the trials. For the first trial, the empirical formula was MgO and the percent composition for magnesium was 60.31% and the percent composition for oxygen was 39.69%. For the second trial, the empirical formula was Mg2O and the percent composition for magnesium was 75.24% and the percent composition for oxygen was 25%. For the last trial, the empirical formula was MgO but that was after the simplification of the original empirical formula, Mg2O2, and the percent composition for magnesium was 60.31% and the percent composition for oxygen was 39.69%. In conclusion, when heat and oxygen were applied to the magnesium, the common empirical formula that was derived from magnesium and oxide was MgO.

Drop a 1 cm magnesium strip in the test tube filled with liquid and time the reaction (time it takes for the strip to dissolve) with a stopwatch. Record the results in a table.

    In this lab, a calorimeter was used to find the enthalpy of reaction for two reactions, the first was between magnesium and 1 molar hydrochloric acid, and the second was between magnesium oxide and 1 molar hydrochloric acid. After the enthalpy for both of these were found, Hess’ law was used to find the molar enthalpy of combustion of magnesium, using the enthalpies for the two previous reactions and the enthalpy of formation for water. The enthalpy of reaction for the magnesium + hydrochloric acid reaction was found to be -812.76 kJ. The enthalpy of reaction for the magnesium oxide + hydrochloric acid reaction was found to be -111.06 kJ. These two enthalpies and the enthalpy of formation for water were manipulated and added together using Hess’s law to get the molar enthalpy of combustion of magnesium. It was found that the molar enthalpy of combustion of magnesium was -987.5 kJ/mol. The accepted enthalpy was -601.6 kJ/mol, which means that there is a percent difference of 64%. This percent difference is very high which indicates that this type of experiment is very inefficient for finding the molar enthalpy of combustion of magnesium. Most likely, a there are many errors in this simple calorimeter experiment that make it inefficient for finding the molar enthalpy of combustion of magnesium.

Equation of magnesium and hydrochloric acid: 2 HCl+ + Mg [IMAGE]Mg2+ + H2 Measuring rates of reaction In this investigation there are two experiments that can be used to test rates of reaction. Using a gas syringe As more gas is produced the plunger inside the syringe moves out of the syringe so the gas can be measured by marks on the syringes length.

Magnesium reaction with Oxygen under the high temperature Introduction The aim of the experiment is to observe how Magnesium reacts with the Oxygen under the high temperature and to calculate percentage yield of the product. Magnesium (solid) + Oxygen (gas) ⟶ Magnesium Oxide (solid) 2Mg (s) + O_2(g) ⟶ 2MgO (s) Results Crucible with the lid on was weighted, mass 1 – 18.43g. Magnesium inside the crucible with the lid on was weighted, mass 2 – 19.09g. Crucible with the lid on, containing Magnesium, was placed on the pipe clay triangle. Bunsen burner was lighted with gentle blue flame, later increased to a roaring flame (with the air hole fully opened) to get reaction going.

During the immersion of the magnesium metal in the hydrochloric acid solution, white bubbles could be seen escaping the surface of the metal as gas was produced during the reaction. Depending on the temperature of the hydrochloric acid and the overall molar concentration, the rate of reaction differed but the same signs were shown. During the reaction between the magnesium metal and higher concentrations of hydrochloric acid, it was observed that the test tube grew quite warm to the touch. As the immersed magnesium strip sank down, it appeared coated in a layer of white bubbles that fizzed like a carbonated drink. In the lower concentrations of hydrochloric acid, the strip spent some time floating at the surface of the solution in the test tube, later sinking down to the bottom as the

A chemical reaction is when substances (reactants) change into other substances (products). The five general types of chemical reactions are synthesis (also known as direct combination), decomposition, single replacement (also known as single displacement), double replacement (also known as double displacement), and combustion. In this lab, the five general types of chemical reactions were conducted and observations were taken before, during, and after the reaction. Then the reactants and observations were used to determine the products to form a balanced chemical equation. The purpose of this lab was to learn and answer the question: How can observations be used to determine the identity of substances produced in a chemical reaction?

Overall, the results were almost as expected. It was predicted that Magnesium and Calcium would have a similar reaction will the hydrochloric acid and produce approximately that same quantity of hydrogen gas. However, the results demonstrated that the Calcium reacted more vigorously than expected and produced a larger quantity of hydrogen gas. The reaction which occurred whilst using Magnesium resulted exactly like the prediction. It was expected that the metal would bubble, eventually dissolve and produce gas which would potentially displace the water in the test tube. With the reaction involving Calcium, it was not predicted that it would heat up the conical flask and react as violently. It was expected that the Tin would either have a

Chemical reactions occur very often in people’s everyday lives. There are six main types of reaction. These include decomposition reactions, synthesis reactions, single-displacement reactions, double displacement reactions, combustion reactions, and nuclear reactions. Both single and double displacement reactions can be broken down into more specific reactions. Single displacement reactions can be classified as metal displacement, which is cation; and halogen displacement, which is anion. Double displacement reactions will break into three different situations: formation of a gas, formation of a solid (precipitate), and neutralization.