Hess’s Law and the Molar Enthalpy of Combustion for Magnesium Purpose: The purpose of the lab ultimately is to find the molar enthalpy of magnesium. This is done by finding the enthalpy changes of reactions (2) and (3). The enthalpy changes of reactions (2) and (3) along with the enthalpy change given for reaction (4) can be used to arrive at a value of the molar enthalpy of combustion of magnesium by using Hess’s Law. Hypothesis: By using Hess’s law to calculate the molar enthalpy of combustion
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Table 8.1- Combustion of magnesium ribbon Observations Reaction was exothermic; magnesium ribbon burned and was glowing a bright white color when ignited. Reactants: Mg and O2 Products: MgO Balanced chemical equation 2Mg + O2 2MgO Table 8.2- Combustion of heptane Observations When holding test tube inverted over heptane flame‚ condensation formed against top walls of the test tube. When the burning splint was added the walls of the test tube became less foggy from the condensation
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Introduction Nivaldo J. Tro describes kinetics as the study of how changes that occur in chemical reactions take place over time‚ and because of its vast utilization in a multitude of industries‚ it may be one of the most significant and fascinating aspects in the entire chemical world. One application of the study of kinetics can be applied to the determination of the rate of a chemical reaction involving a certain selection of chemicals (FD&C Blue #1 and sodium hypochlorite). The purpose of the
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crystal with a bromobenzene solution with a stir bar. Once the stirring began‚ the solution turned brown and over time began to lighten up. The color change to brown indicated that the reaction began and this is why an iodine crystal was placed in the solution. The reaction started to boil due to its own reflux so heat didn’t need to be applied. Next the anhydrous ether solution was added very slowly in a dropwise manner with a needle through the septum cap on the condenser. This was added through the
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Materials: • Graduated cylinder • 2 marbles • Liquids to test such as water‚ corn syrup‚ canola oil‚ motor oil • Masking tape • 1 cm ruler • Stopwatch that is accurate to 0.1 or 0.01 seconds SAFETY NOTE: See Texas Science Safety Manual for lab and investigation guidelines: http://www.tenet.edu/teks/science/safety/safety_manual.html Engagement: Place a wooden ramp on a stack of books. Challenge students to predict which of three liquids (syrup‚ water‚ and motor oil) will reach the bottom
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carboxylic acids and alcohols with the presence of a catalyst. A carboxylic acid contains the -COOH group‚ and in an ester the hydrogen in this group is replaced by a hydrocarbon group of some kind. Sulfuric acid (H2SO4)is used as a catalyst for this reaction in order to accelerate the rate at which the product is formed. The general formula of an ester is RCOOR’ in which R is the alkyl group that comes from the carboxylic acid while R’ is the alkyl group that comes from the alcohol and COO is the functional
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Title : Measuremnt of pH With Indicators Aim : 1.To investigate concentration of hydrogen ions in hydrochloric acic and colour changes of indicators 2.To determine standard solutions and the unknowns Variables Independent variable : Concentration of hydrogen ions in hydrochloric acid.The presence of hydrogen ions is varied by using 5 different concentration of hydrochloric acid of 0.1mol/L‚0.01mol/L‚0.001mol/L‚0.0001mol/L‚0.0000mol/L Dependent variable : Colour changes of indicators
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Introduction The purpose of this lab is to be able to observe the reaction rates of different chemical substances‚ by looking at which substance is the fastest reactant. This is what chemical kinetics is. Reaction rate is the change in the concentration of a reactant or product in a chemical reaction per unit time. In this lab the requirement was to be able to calculate each Average reaction rate which is the change in reactant or product concentration at a given time interval. Some equations that
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The effect of time on enzyme reaction. Abstract: In this lab investigation we will observe how the amount of hydrogen peroxide is affected by catalase over time. The enzyme was added to 10 mL’s of hydrogen peroxide and observed over time to determine the relation between time and enzyme activity. The hypothesis stated that as time increased substrate would decrease. Therefore I predicted that at 60 seconds‚ there would be the least amount of H2O2. The enzyme activity mirrored my predictions
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was soluble in water as well‚ but it had a very low melting point. All the substances except for sodium carbonate did not pass the requirements‚ and therefore sodium carbonate is the best possible substance. In order to prove this‚ I conducted a lab to determine the solubility‚ conductivity‚ and melting point of each substance. First‚ I made sure to obtain a Bunsen burner‚ evaporating dish‚ ethanol‚ the four substances‚ distilled water‚ conductivity probe‚ wash bottles‚ test tubes‚ and a beaker
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