Lab: Heat Of Combustion Measured A

2. The second source of error in the lab is when opening the lid of the crucible which allowed smoke of magnesium oxide to escape. During the lab, we removed the lid a couple of times to allow oxygen to enter the crucible so the magnesium reacts with the air to form magnesium oxide. However, the smoke could have easily escaped from the crucible because of the strong force of heat from the laboratory burner. This could have affected the lab results by decreasing the final mass when some of the product have escaped.

Materials:Magnesium stripCrucibleCrucible coverClay triangleIron ringRetort standTongsBalanceBunsen burnerProcedure:1.obtained a strip of magnesium between 30-40 cm long2.coiled magnesium strip into a tight roll3.measured the mass of the crucible and cover4.Added the magnesium strip to the crucible and measured the

An Investigation into the Enthalpies of the Combustion of Alcohols = == == == ==

The purpose of this lab was to test the law of definite proportions for the synthesis reaction of combusting magnesium. In this lab, the polished magnesium ribbon was placed in covered crucible and was heated in order for it to react with Oxygen presented in air and in water provided. The result showed that Magnesium oxide formed through chemical reaction was made up of 60.19% magnesium and 39.81% oxygen, which is approximate proportion of both particles in every Magnesium oxide compound. From this lab it can be concluded that the law of definite proportion stating that the elements in a pure compound combine in definite proportion to each other is factual.

    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.

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)

The purpose of this experiment was to find, compare, and contrast the mass, volume, and densities of copper and zinc pennies. Information about the pennies was acquired before the start of the lab. The pre-lab research stated that any pennies that were minted before 1982 are composed of pure copper, while any pennies after 1982 are made out of zinc. The densities of copper -- 8.96 grams per centimeters cubed -- and zinc -- 7.13 grams per centimeters cubed -- were also information that was acquired before starting the experiment. With knowing the density of the two metals, this hypothesis was formed: If the mass and volume of pennies made out of zinc and copper are both measured, then the copper pennies will have a greater mass, because copper has a greater density than zinc. This hypothesis was formed because density equals mass over volume and if the mass is greater in an object that has the same volume, then the density of the object will be greater than the other.

The objective of this lab was first to convert the mass of a compound to the number of moles and number of molecules and then determine the concentration of salt and its component. The first thing we did was get the mass of an empty container by using a scale and it came out to be 16.87g. Next thing we did was pick a substance which in this case it was Potassium Chloride and placed it on the scale to get a total mass of 31.20g. The container the Potassium Chloride was in only had a mass of 16.87g which means that the mass of the substance was 14.33g. To convert the mass to the number of moles we took the amount of the substance 14.33g and divided it by the mass of Potassium Chloride 74.55g and figured out that the number of moles was 0.192.

How empirical formula of Magnesium Oxide is obtained by heating Magnesium in the presence of air?

This lab was to see chemical reactions with different liquids. This was important to find the unknown substance. The controlled variable was the unknown powder, since it doesn’t change. The independent variable was the liquids. These liquids were vinegar, iodine, and water. Lastly, the dependent variable is the chemical reactions. The reaction was affected by the different liquids. If the liquids are changed then the chemical reactions will be different, because they have different properties, causing the atoms to bond differently.

This is a combustion process in which two substances, magnesium and oxygen, react chemically resulting in a new compound that is different from the original elements. In this chemical reaction, irreversible chemical changes take place. In the presence of fire, magnesium readily combines with the oxygen and changes its original physical properties such as being a silver, smooth metal to a white, powder-like substance. This happens to magnesium due to its high reactivity because it only contains two valence electrons. When the flame of the lighter hits the metal, the reaction continues until the whole strip completely changes into ash, as long as oxygen is available in the air. After all the magnesium burns, the reaction is complete, and what

The aim of this experiment was to test the heat of combustion over a period of time, and the energy required to combust alcohols with different carbon chain levels. It was hypothesised that the higher the carbon chain of the alcohol present, the faster the heat of combustion will occur. Meaning more energy will be released for a higher carbon chain. After calculating the results from the experiment it was found that the hypothesis was partially supported. The reasoning for this is as the alcohol that posses a higher carbon chain, generally increased there reaction rates. However there were a few exceptions to this rule.

1. Figure 1 shows the heating phases that occurred during the experiment. There is an exponential decrease in temperature as the depth of the water increases. Water has a high specific heat capacity which means that it can resist changes in temperature. This is coupled with the fact that solar radiation progressively loses its penetrative ability as the depth of the water increases. The light attenuation in lakes describes the decrease in actual light that can penetrate a water column as well as the fact that most of the energy that the light has is absorbed by the surface of the water.

The goal of this lab was to find the empirical formula of Magnesium sulfate hydrate. To determine this formula, we measured and recorded the mass of an empty clay crucible. We then poured a small amount of Epsom salt into the crucible, and then recorded the mass of the filled crucible. We then subtracted the weight of the empty crucible from the weight of the crucible with Epsom salt to determine the mass of the Epsom salt. We then lit a bunsen burner, and manipulated the airflow to allow for the optimal (hottest) flame. We then placed the bunsen burner under a clay triangle, suspended roughly 4 cm above the nozzle of the burner. Next, the crucible with the Epsom salt was placed on the triangle, and was heated by the bunsen burner for 8 minutes. After 8 minutes, the bunsen burner was turned off, and the crucible was set to cool for 5 minutes. After cooling, we measured and recorded the mass of the crucible. We then placed the crucible over the bunsen burner for 5 minutes, and then set it to cool for another 5 minutes. The mass of the crucible was then measured and recorded again.

Thermal conductivity heat is transferred as a consequence of temperature difference between 2 bodies, heat energy passes form a hotter to the colder body. Specific heat capacity is the amount of heat energy required in joules to raise 1kg of a substance by 1 degree Celsius, different substances absorb heat energy at different rates not all substances require the same amount of heat energy to increase the internal temperature of a substance this depends on the mass and the material it’s self. To demonstrate specific heat capacity of a solid an experiment was carried out using 1kg aluminium mass and 1kg copper mass heat was conducted to the masses by