Experiment 11 Calorimetry and Hess’s Law Purpose- To determine the change in enthalpy for four reactions using calorimetry and Hess’s Law Procedures: A. Calibration of the Calorimeter 1. Obtain two copper cylinders and a Styrofoam cup with lid from your lab instructor. Check out a digital thermometer display from the storeroom window. 2. Set up a hot water bath using a 600mL beaker‚ ring stand‚ and Bunsen burner. Weigh the two copper cylinders
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|Zn |Mg |Cu |Pb | | |(+) clear liquid but the |(+) a black spot appeared on|(-) no reaction occurred |(-) no reaction | |Pb(NO3)2 |Zinc itself turned glittery |the sliver of magnesium. | | | | |(+) the liquid looks |(+)
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Heats of Reaction Lab Report Purpose: To measure the heats of reaction for three related exothermic reactions and to verify Hess’s Law of Heat Summation. NaOH(s) ( Na+(aq) + OH-(aq) ΔH = -10.6kcal/mol NaOH(s) + H+(aq) + Cl-(aq) ( H2O + Na+(aq) + Cl-(aq) ΔH = -23.9kcal/mol Na+(aq) + OH-(aq) + H+(aq) + Cl-(aq) ( H2O + Na+(aq) + Cl-(aq) ΔH = -13.3kcal/mol Background: Energy changes occur in all chemical reactions; energy is either absorbed or released. If energy is released in
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Regents Chemistry Quarter 1 Midterm Review 1. The percent by mass of oxygen in Na2SO4 (formula mass = 142) is closest to 1) 11% 3) 45% 2) 22% 4) 64% 2. Given the unbalanced equation: __Al(s) + __O2(g) → __Al2O3(s) 3. 4. 5. 6. 7. balance the equation using smallest whole number coefficients. The percent by mass of aluminum in Al2O3 is approximately 1) 18.9 3) 47.1 2) 35.4 4) 52.9 What is the approximate percent composition by mass of CaBr2 (formula mass = 200)
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The purpose of this lab was to see which solutions are soluble and which are not. We were able to see this by mixing certain solutions together and observing changes that occurred. The procedure for this experiment included a few different steps. The first steps were to add the nitrate solutions into the lettered parts of the 96-well plate. Once you were done with that‚ you were supposed to add the sodium solutions to the numbered parts of the 96-well plate‚ so that the solutions were added together
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Heat of Neutralization Lab Objective: The objective of this lab was to measure‚ using a calorimeter‚ the energy changes accompanying neutralization reactions. Background: Chemical changes are always accompanied by a change in energy‚ typically as heat. If the reaction releases heat (ΔH < 0) then the reaction is exothermic. If the reaction absorbs heat (ΔH > 0) then the reaction is endothermic. The quantity of heat is measured experimentally by having the reaction take place in an insulated container called a
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ATLANTIC COLLEGE CHEMISTRY DEPARTMENT (Written by Dr Geoffrey Neuss) CONTENTS Page Introduction 1 Assessment of Practical Work 3 Error and uncertainty 7 Significant figures 8 Title 1. Some common chemical reactions. 9 2. A traditional acid-alkali titration. 10 3. Analysis of aspirin tablets
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different chemical reactions and determine if they are exothermic or endothermic. Apparatus: • Test tubes {Around 10-12 in number} • Test-tube rack • Spatula • Digital thermometer { ± 0.1° C} • Digital balance {± 0.01 g} • Measuring cylinder {± 0.5cm³} • Different chemicals Introduction/Theory: Exothermic reactions are those reactions that release energy in the form of heat. Endothermic reactions need to absorb energy in the form of heat to proceed. Enthalpy
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Procedure Access the virtual lab and complete the experiments. Part One (Flame Test): 1. Create and complete a data table for Part One of the lab. It should include the name of the element (or unknown) examined and the color of the observed flame: Barium-green Calcium-red Sodium-yellow Rubidium-purple Potassium-blue Lithium-pink 2. Identify each unknown from Part One of the lab and briefly explain why you identified each unknown as you did.: Unknown 1-yellow. I think it is Sodium because
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Specific Heat Lab Objective: Find the specific heat of the unknown metal given using calorimetry. Background Theory: In every reaction‚ energy is transferred between a system and its environment. A system encompasses the substances that are involved in a reaction‚ and everything else in the universe other than the system is called the environment. The standard SI unit of energy is Joules (J). Temperature is the level of excitement of the atoms in a substance. In most cases‚ energy is
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