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A current of 3.78 A is passed through a
Fe(NO3)2 solution. How long (in hours) would this current have to be
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20200625172235global Health.edited
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The term Global health governance means the processes and institutions of management that are specific to health issues (Forum on Microbial Threats; ...
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set up an osmosis experiment and able to answer 12 questions
Get four 8 oz. cups from the lab kit. Place a piece of tape on each cup or glass. Using a pen or marker, label the tape on ...
set up an osmosis experiment and able to answer 12 questions
Get four 8 oz. cups from the lab kit. Place a piece of tape on each cup or glass. Using a pen or marker, label the tape on each cup with one of the following percentages: 0%, 1.75%, 3.5%, and 7%.Using the graduated cylinder, measure out 100 mL of distilled water. Pour the water into the fifth, unlabeled cup.Measure out 1.5 level teaspoons of salt and add it to the unlabeled cup containing 100 mL of distilled water. Mix completely. This is the 7% salt solution.Using the graduated cylinder, measure out 50 mL of this mixture and pour it from the graduated cylinder into the cup labeled 7%.Add distilled water up to the 100 mL mark of the graduated cylinder to make the next dilution. Adding 50 mL distilled water to 50 mL of a 7% solution will result in 100 mL of a 3.5% solution.Using the graduated cylinder, measure out 50 mL of the 3.5% solution and pour it from the graduated cylinder into the cup labeled 3.5%.Add distilled water up to the 100 mL mark of the solution in the graduated cylinder to make the next dilution. Adding 50 mL of distilled water to the 50 mL of the 3.5% solution will result in 100 mL of a 1.75% solution.Using the graduated cylinder, measure out 50 mL of the 1.75% solution and pour it from the graduated cylinder into the cup labeled 1.75%.Empty the remaining 1.75% solution down the drain of the sink and rinse out the graduated cylinder with tap water.Using a sharp steak or kitchen knife, slice eight pieces of potato exactly 10 mm x 10 mm x 40 mm (1 cm x 1 cm x 4 cm). It is critically important that these potato core pieces are cut as precisely as possible; they need to all start out having the same volume. A single- edge razor blade may work better than a knife.Determine the volume of the potato cores. The volume, is calculated by multiplying the width x height x length. Therefore, each core starts out with a volume of 4,000 cubic millimeters or 4 cubic centimeters. Measure the cores with both the mm ruler and the calipers. Measuring with the calipers to the nearest millimeter will be good enough for this lab. Create a data table like the one below to record the beginning and ending volumes.Table 1. Potato core measurements0% salt solution1.75% salt solution3.5% salt solution7% salt solutionBeginning average volume (cu mm)Ending average volume (cu mm)Percent differencePlace two measured cores into each solution overnight, or for at least 8 hours. That time period is not critical to the results; it can be longer.Remove the cores from one of the cups and pat them dry with a paper towel. The solution may now be discarded down the drain of a sink.Using the caliper, measure the height, width, and length of the cores, and then determine the volume of each core. Average the measurements for the two cores and record in the data table above. The cores can now be discarded.Repeat Steps 13 - 14 three more times: one time for each cup.Illustration of the Importance of Surface-to-Volume RatiosCalculate the surface-to-volume ratio of the following potato cubes:CUBE 1: Length, width, and height are all 5 mmCUBE 2: Length, width, and height are all 3 mmEffect of cell size on diffusion rateWith clean hands, cutting board, and knife, cut the skin off of the potato.Using the knife, cut two cubes of potato with dimensions of 1 cm x 1 cm x 1 cm.Using the knife, cut two cubes of potato with dimensions 1.5 cm x 1.5 cm x 1.5 cm.Using the knife, cut two cubes of potato with dimension of 2 cm x 2 cm x 2 cm.Place distilled water into a cup or glass. Add the vial of food coloring to the water until a dark color is achieved.Carefully place the potato cubes in the solution. The cubes must be completely submerged in the water. Let them stand in the solution for 2 to 4 hours.After 2 to 4 hours, remove the cubes. Using the knife, cut each cube in half.Using the ruler, measure how far the solution has diffused into each potato cube.Record the results. A sample data table is included below that may be used to organize and record the results.Complete the following calculations to determine the rate of diffusion and record the results.Rate of Diffusion (cm/min)= Distance of diffusion ÷ time.CubeDistance of DiffusionRate of Diffusion1 cm cubed1 cm cubed1.5 cm cubed1.5 cm cubed2 cm cubed2 cm cubedAverage Rate of Diff.What were the percent differences between the volumes of the potatoes in the osmosis experiment for each salt solution? (8 points)0%1.75%3.5%7%What extraneous variables might have affected how the results came out in the osmosis experiment? Describe three. (6 points)In osmosis, which direction does water move with respect to solute concentration? (2 points)Answer the following questions:Explain what would happen to a freshwater unicellular organism if it were suddenly released into a saltwater environment. Use the terms isotonic, hypotonic and hypertonic in the answer. (3 points)What would happen if a marine organism were placed in freshwater? (3 points)A student purchases and weighs 5 pounds of carrots from a local grocery store. She notices that the grocery store constantly sprays its produce with distilled water. After returning home, she weighs the carrots again and discovers that they weigh only 4.2 lbs. They also no longer seem as crisp and taut. Provide a possible explanation for why the carrots weighed more at the store, based on the information learned in this lab. (5 points)People always say that leeches can be removed from the body by pouring salt on them. Based on what the student learned about osmosis, provide an explanation that supports or refutes this information. (5 points)What is the surface-to-volume ratio and rate of diffusion for each potato cube from Procedure 3b? (6 points)Cube 1 surface-to-volume ratioCube 1 rate of diffusionCube 2 surface-to-volume ratioCube 2 rate of diffusionCube 3 surface-to-volume ratioCube 3 rate of diffusionAssume the potato cubes are cells. Which cube would be most efficient at moving materials into and out of the cube? Briefly explain the answer. (4 points)From what was observed in the potato procedure, how do the rate of diffusion and surface-to-volume ratio limit cell size? (5 points)One night, Hans decides to cook a hamburger and spaghetti with meatballs. To test ideas of surface-to-volume ratios, he makes a quarter pound hamburger and a quarter pound meatball and cooks them at the same temperature. Which food item will cook the fastest and why? (5 points)While watching a special on animals, Brianna discovers that hares tend to lose heat through their ears. Based on this and what is known about surface-to-volume ratios, propose an explanation as to why hares that live in hot climates (such as the desert) have large, extended ears. (5 points)In the Spirogyra cells observed on the virtual microscope, about how many circular green chloroplasts were seen in a single cell at 40X magnification? (2 points)What were the percent differences between the volumes of the potatoes in the osmosis experiment for each salt solution? (8 points)0%1.75%3.5%7%What extraneous variables might have affected how the results came out in the osmosis experiment? Describe three. (6 points)In osmosis, which direction does water move with respect to solute concentration? (2 points)Answer the following questions:Explain what would happen to a freshwater unicellular organism if it were suddenly released into a saltwater environment. Use the terms isotonic, hypotonic and hypertonic in the answer. (3 points)What would happen if a marine organism were placed in freshwater? (3 points)A student purchases and weighs 5 pounds of carrots from a local grocery store. She notices that the grocery store constantly sprays its produce with distilled water. After returning home, she weighs the carrots again and discovers that they weigh only 4.2 lbs. They also no longer seem as crisp and taut. Provide a possible explanation for why the carrots weighed more at the store, based on the information learned in this lab. (5 points)People always say that leeches can be removed from the body by pouring salt on them. Based on what the student learned about osmosis, provide an explanation that supports or refutes this information. (5 points)What is the surface-to-volume ratio and rate of diffusion for each potato cube from Procedure 3b? (6 points)Cube 1 surface-to-volume ratioCube 1 rate of diffusionCube 2 surface-to-volume ratioCube 2 rate of diffusionCube 3 surface-to-volume ratioCube 3 rate of diffusionAssume the potato cubes are cells. Which cube would be most efficient at moving materials into and out of the cube? Briefly explain the answer. (4 points)From what was observed in the potato procedure, how do the rate of diffusion and surface-to-volume ratio limit cell size? (5 points)One night, Hans decides to cook a hamburger and spaghetti with meatballs. To test ideas of surface-to-volume ratios, he makes a quarter pound hamburger and a quarter pound meatball and cooks them at the same temperature. Which food item will cook the fastest and why? (5 points)While watching a special on animals, Brianna discovers that hares tend to lose heat through their ears. Based on this and what is known about surface-to-volume ratios, propose an explanation as to why hares that live in hot climates (such as the desert) have large, extended ears. (5 points)one month ago
chemical compounds lab
Background: This week, you will be tasked with investigating the solubility of several chemical compoundsChemists routine ...
chemical compounds lab
Background: This week, you will be tasked with investigating the solubility of several chemical compoundsChemists routinely measure the heat involved in a chemical change either experimentally or from enthalpy changes observed in other related reactions. In order to do the latter, the application of Hess’s law is required:If a process can be written as the sum of several stepwise processes, the enthalpy change of the total process equals the sum of the enthalpy changes of the various steps.In this experiment, you will determine and compare the quantity of heat energy released in three exothermic chemical reactions through application of Hess’s law.Reaction 1: NaOH(s) → Na+(aq) + OH-(aq) + x1 kJReaction 2: NaOH(s) + HCl(aq) → H2O(l) + Na+(aq) + OH-(aq) + x2 kJReaction 3: NaOH(aq) + HCl(aq) → H2O(l) + Na+(aq) + OH-(aq) + x3 kJIn order to accurately measure the heat released in each reaction, we will be using a calorimeter. As discussed in the textbook, a calorimeter is a device used to measure the amount of heat involved in a chemical or physical process; the calorimeter used in this experiment will be a Styrofoam cup. In the reactions above, the variables x1, x2, and x3 are the heats that are evolved during the reactions. The change in temperature that occurs for each reaction will be used to calculate the energy released in kJ/mol of NaOH used. We will assume for our calculations that any heat transferred to the Styrofoam cup and surrounding air will be negligible; we will also assume that the specific heat of water is 4.184 J/g∙°C. Thus, the applicable equation is simplyThere are several objectives of this lab:Explore the technique of calorimetry, andCalculate and interpret heat and related properties using typical calorimetry data.Before you start this laboratory assignment, you are encouraged to review Section 5.2 (p. 238) and Section 5.3 (p. 251) in the textbook. Throughout this laboratory assignment, you will be required to perform and thoroughly document your data and calculations. Be sure to record all observations and any relevant notes that you think you will need to include in your laboratory report; refer to the end of this document for information that must be included in your final report.
Procedure: Preparing the Lab IFrom the course home page, access the lab environment by clicking on the Virtual Lab link.After the lab environment loads, click ‘File’ then ‘Load an Assignment.’Select the ‘Thermochemistry’ category.Select the ‘Heats of Reaction’ assignment.Review the data table for this lab (see the end of this document).Evaluate the reactions shown in the ‘Background’ section above and draft a hypothesis based on this information; write your hypothesis in your notes for reference later.At this point, you have prepared the laboratory for the experiment with the required supplies to complete your experiments.In the ‘Glassware’ menu, place a 50-mL graduated cylinder and a foam cup onto the workbench. From the ‘Tools’ menu, add a balance (scale) to the workbench. Then, move the distilled water and solid NaOH to the workbench as well.Transfer 50.0 mL of distilled water to the foam cup. To do this, you must first transfer the water to the graduated cylinder then to the foam cup. After dragging the water to the graduated cylinder, enter ‘50.0’ and click ‘Pour.’ Record the initial temperature of the water in your data table.Tare the balance after adding the foam cup, then weigh 1.00 g of solid NaOH pellets directly into the foam cup. Remove the scale from the workbench at this point.Pour the entire contents of the graduated cylinder into the foam cup and immediately record the highest temperature observed and the mass of the contents of the cup. In a real laboratory, you have a temperature probe (like a thermometer) inserted into the foam cup to record the maximum temperature.Take the 0.50 M HCl solution, a foam cup, the solid NaOH, a 50-mL graduated cylinder, and a balance from the from the Stockroom and place it on the workbench.Repeat Steps 7-10 but replace the 50 mL of water with 50 mL of the 0.50 M HCl solution. After mixing the HCl solution with the solid NaOH, immediately record the highest observed temperature.Clear the workbench.Take out another graduated cylinder, a fresh foam cup, the 1.0 M HCl and 1.0 M NaOH solutions and add them to the workbench.Measure 25.0 mL of the 1.0 M HCl solution into the foam using the graduated cylinder. Using a clean graduated cylinder (to avoid cross-contamination), measure out 25.0 mL of the 1.0 M NaOH solution.Pour the NaOH solution into the foam cup and immediately record the highest observed temperature.Clear the workbench.Complete the table shown below in the ‘Data’ section by filling in the values recorded during the experiments or those produced from the required calculations.Write out the net ionic equations for all three reactions referring to the initial reactions shown in the ‘Background’ section of this template. Be sure to use proper notation when writing your equations as you will include these in the final draft of your report.The energy, x1, in Reaction 1 represents the energy of solution for one mole of solid NaOH. Look at the net ionic equations for Reactions 2 and 3, and make a similar statement concerning the significance of x2 and x3 and their connection to Hess’s law. Record your statements in the ‘Notes’ section below for review later.Find the difference between the value of x2 and the sum of x1 plus x3.; let x4 be equivalent to the sum of x1 and x3and let x5 be the difference between x2 and x5. This calculation scheme is shown below. Make notes about any similarities or differences between the values in your notes.x4 = x1 + x3x5 = x2 – x4Calculate the percent difference between x2 and x4 according to the equation below. (Assume x2 to be the accepted value.) Record the calculation in your notes.Performing the Reactions IPerforming the Reactions IIPerforming the Reactions IIIData Analysis
NotesThis section should include notes about any observations or data collected during the lab.Begin typing here.DataThis section will include all data collected during the lab.Thermochemical Data Tinitial (°C)Tfinal (°C)ΔT (°C)moles NaOHqreaction (kJ)ΔHrxnReaction 1Reaction 2Reaction 3*Note: You can copy and paste your data table into your report later.Insert the net ionic equations here:Reaction 1:Reaction 2:Reaction 3:Report RequirementsThis section contains key information that must be included in your typed report.Define the problem/goals in a manner that is clear and insightful.Identification of the strategies/procedures used during the lab.Clear hypothesis statement and other potential solutions that identify any relevant contextual factors (i.e. real-world costs). Consider alternative ways to confirm Hess’s law experimentally.Clear presentation of data including any tables or other figures that are relevant to understanding your stated conclusions at the end of the report. The following items are required in your report:Data tableNet ionic equationsPercent difference calculation.Clearly stated results (evidence confirming Hess’s law) and discussion possible improvements to the procedure.Conclusive statements arguing in favor of your findings.Note: All reports will be graded using the rubric embedded within the course.Here are some questions to consider as you write your report:Does my problem statement make sense?Have I summarized my strategies/procedures well enough to be replicated by an outsider?Did I have a valid hypothesis at the start of the lab? Have I expressed this in my report?Do my tables and/or graphs make sense?Are my conclusions valid based on my supplied data?Did I thoroughly summarize my laboratory experience in a concise, factual way such that the reader can understand my processes and findings in the conclusion section alone?
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20200625172235global Health.edited
The term Global health governance means the processes and institutions of management that are specific to health issues (F ...
20200625172235global Health.edited
The term Global health governance means the processes and institutions of management that are specific to health issues (Forum on Microbial Threats; ...
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set up an osmosis experiment and able to answer 12 questions
Get four 8 oz. cups from the lab kit. Place a piece of tape on each cup or glass. Using a pen or marker, label the tape on ...
set up an osmosis experiment and able to answer 12 questions
Get four 8 oz. cups from the lab kit. Place a piece of tape on each cup or glass. Using a pen or marker, label the tape on each cup with one of the following percentages: 0%, 1.75%, 3.5%, and 7%.Using the graduated cylinder, measure out 100 mL of distilled water. Pour the water into the fifth, unlabeled cup.Measure out 1.5 level teaspoons of salt and add it to the unlabeled cup containing 100 mL of distilled water. Mix completely. This is the 7% salt solution.Using the graduated cylinder, measure out 50 mL of this mixture and pour it from the graduated cylinder into the cup labeled 7%.Add distilled water up to the 100 mL mark of the graduated cylinder to make the next dilution. Adding 50 mL distilled water to 50 mL of a 7% solution will result in 100 mL of a 3.5% solution.Using the graduated cylinder, measure out 50 mL of the 3.5% solution and pour it from the graduated cylinder into the cup labeled 3.5%.Add distilled water up to the 100 mL mark of the solution in the graduated cylinder to make the next dilution. Adding 50 mL of distilled water to the 50 mL of the 3.5% solution will result in 100 mL of a 1.75% solution.Using the graduated cylinder, measure out 50 mL of the 1.75% solution and pour it from the graduated cylinder into the cup labeled 1.75%.Empty the remaining 1.75% solution down the drain of the sink and rinse out the graduated cylinder with tap water.Using a sharp steak or kitchen knife, slice eight pieces of potato exactly 10 mm x 10 mm x 40 mm (1 cm x 1 cm x 4 cm). It is critically important that these potato core pieces are cut as precisely as possible; they need to all start out having the same volume. A single- edge razor blade may work better than a knife.Determine the volume of the potato cores. The volume, is calculated by multiplying the width x height x length. Therefore, each core starts out with a volume of 4,000 cubic millimeters or 4 cubic centimeters. Measure the cores with both the mm ruler and the calipers. Measuring with the calipers to the nearest millimeter will be good enough for this lab. Create a data table like the one below to record the beginning and ending volumes.Table 1. Potato core measurements0% salt solution1.75% salt solution3.5% salt solution7% salt solutionBeginning average volume (cu mm)Ending average volume (cu mm)Percent differencePlace two measured cores into each solution overnight, or for at least 8 hours. That time period is not critical to the results; it can be longer.Remove the cores from one of the cups and pat them dry with a paper towel. The solution may now be discarded down the drain of a sink.Using the caliper, measure the height, width, and length of the cores, and then determine the volume of each core. Average the measurements for the two cores and record in the data table above. The cores can now be discarded.Repeat Steps 13 - 14 three more times: one time for each cup.Illustration of the Importance of Surface-to-Volume RatiosCalculate the surface-to-volume ratio of the following potato cubes:CUBE 1: Length, width, and height are all 5 mmCUBE 2: Length, width, and height are all 3 mmEffect of cell size on diffusion rateWith clean hands, cutting board, and knife, cut the skin off of the potato.Using the knife, cut two cubes of potato with dimensions of 1 cm x 1 cm x 1 cm.Using the knife, cut two cubes of potato with dimensions 1.5 cm x 1.5 cm x 1.5 cm.Using the knife, cut two cubes of potato with dimension of 2 cm x 2 cm x 2 cm.Place distilled water into a cup or glass. Add the vial of food coloring to the water until a dark color is achieved.Carefully place the potato cubes in the solution. The cubes must be completely submerged in the water. Let them stand in the solution for 2 to 4 hours.After 2 to 4 hours, remove the cubes. Using the knife, cut each cube in half.Using the ruler, measure how far the solution has diffused into each potato cube.Record the results. A sample data table is included below that may be used to organize and record the results.Complete the following calculations to determine the rate of diffusion and record the results.Rate of Diffusion (cm/min)= Distance of diffusion ÷ time.CubeDistance of DiffusionRate of Diffusion1 cm cubed1 cm cubed1.5 cm cubed1.5 cm cubed2 cm cubed2 cm cubedAverage Rate of Diff.What were the percent differences between the volumes of the potatoes in the osmosis experiment for each salt solution? (8 points)0%1.75%3.5%7%What extraneous variables might have affected how the results came out in the osmosis experiment? Describe three. (6 points)In osmosis, which direction does water move with respect to solute concentration? (2 points)Answer the following questions:Explain what would happen to a freshwater unicellular organism if it were suddenly released into a saltwater environment. Use the terms isotonic, hypotonic and hypertonic in the answer. (3 points)What would happen if a marine organism were placed in freshwater? (3 points)A student purchases and weighs 5 pounds of carrots from a local grocery store. She notices that the grocery store constantly sprays its produce with distilled water. After returning home, she weighs the carrots again and discovers that they weigh only 4.2 lbs. They also no longer seem as crisp and taut. Provide a possible explanation for why the carrots weighed more at the store, based on the information learned in this lab. (5 points)People always say that leeches can be removed from the body by pouring salt on them. Based on what the student learned about osmosis, provide an explanation that supports or refutes this information. (5 points)What is the surface-to-volume ratio and rate of diffusion for each potato cube from Procedure 3b? (6 points)Cube 1 surface-to-volume ratioCube 1 rate of diffusionCube 2 surface-to-volume ratioCube 2 rate of diffusionCube 3 surface-to-volume ratioCube 3 rate of diffusionAssume the potato cubes are cells. Which cube would be most efficient at moving materials into and out of the cube? Briefly explain the answer. (4 points)From what was observed in the potato procedure, how do the rate of diffusion and surface-to-volume ratio limit cell size? (5 points)One night, Hans decides to cook a hamburger and spaghetti with meatballs. To test ideas of surface-to-volume ratios, he makes a quarter pound hamburger and a quarter pound meatball and cooks them at the same temperature. Which food item will cook the fastest and why? (5 points)While watching a special on animals, Brianna discovers that hares tend to lose heat through their ears. Based on this and what is known about surface-to-volume ratios, propose an explanation as to why hares that live in hot climates (such as the desert) have large, extended ears. (5 points)In the Spirogyra cells observed on the virtual microscope, about how many circular green chloroplasts were seen in a single cell at 40X magnification? (2 points)What were the percent differences between the volumes of the potatoes in the osmosis experiment for each salt solution? (8 points)0%1.75%3.5%7%What extraneous variables might have affected how the results came out in the osmosis experiment? Describe three. (6 points)In osmosis, which direction does water move with respect to solute concentration? (2 points)Answer the following questions:Explain what would happen to a freshwater unicellular organism if it were suddenly released into a saltwater environment. Use the terms isotonic, hypotonic and hypertonic in the answer. (3 points)What would happen if a marine organism were placed in freshwater? (3 points)A student purchases and weighs 5 pounds of carrots from a local grocery store. She notices that the grocery store constantly sprays its produce with distilled water. After returning home, she weighs the carrots again and discovers that they weigh only 4.2 lbs. They also no longer seem as crisp and taut. Provide a possible explanation for why the carrots weighed more at the store, based on the information learned in this lab. (5 points)People always say that leeches can be removed from the body by pouring salt on them. Based on what the student learned about osmosis, provide an explanation that supports or refutes this information. (5 points)What is the surface-to-volume ratio and rate of diffusion for each potato cube from Procedure 3b? (6 points)Cube 1 surface-to-volume ratioCube 1 rate of diffusionCube 2 surface-to-volume ratioCube 2 rate of diffusionCube 3 surface-to-volume ratioCube 3 rate of diffusionAssume the potato cubes are cells. Which cube would be most efficient at moving materials into and out of the cube? Briefly explain the answer. (4 points)From what was observed in the potato procedure, how do the rate of diffusion and surface-to-volume ratio limit cell size? (5 points)One night, Hans decides to cook a hamburger and spaghetti with meatballs. To test ideas of surface-to-volume ratios, he makes a quarter pound hamburger and a quarter pound meatball and cooks them at the same temperature. Which food item will cook the fastest and why? (5 points)While watching a special on animals, Brianna discovers that hares tend to lose heat through their ears. Based on this and what is known about surface-to-volume ratios, propose an explanation as to why hares that live in hot climates (such as the desert) have large, extended ears. (5 points)one month ago
chemical compounds lab
Background: This week, you will be tasked with investigating the solubility of several chemical compoundsChemists routine ...
chemical compounds lab
Background: This week, you will be tasked with investigating the solubility of several chemical compoundsChemists routinely measure the heat involved in a chemical change either experimentally or from enthalpy changes observed in other related reactions. In order to do the latter, the application of Hess’s law is required:If a process can be written as the sum of several stepwise processes, the enthalpy change of the total process equals the sum of the enthalpy changes of the various steps.In this experiment, you will determine and compare the quantity of heat energy released in three exothermic chemical reactions through application of Hess’s law.Reaction 1: NaOH(s) → Na+(aq) + OH-(aq) + x1 kJReaction 2: NaOH(s) + HCl(aq) → H2O(l) + Na+(aq) + OH-(aq) + x2 kJReaction 3: NaOH(aq) + HCl(aq) → H2O(l) + Na+(aq) + OH-(aq) + x3 kJIn order to accurately measure the heat released in each reaction, we will be using a calorimeter. As discussed in the textbook, a calorimeter is a device used to measure the amount of heat involved in a chemical or physical process; the calorimeter used in this experiment will be a Styrofoam cup. In the reactions above, the variables x1, x2, and x3 are the heats that are evolved during the reactions. The change in temperature that occurs for each reaction will be used to calculate the energy released in kJ/mol of NaOH used. We will assume for our calculations that any heat transferred to the Styrofoam cup and surrounding air will be negligible; we will also assume that the specific heat of water is 4.184 J/g∙°C. Thus, the applicable equation is simplyThere are several objectives of this lab:Explore the technique of calorimetry, andCalculate and interpret heat and related properties using typical calorimetry data.Before you start this laboratory assignment, you are encouraged to review Section 5.2 (p. 238) and Section 5.3 (p. 251) in the textbook. Throughout this laboratory assignment, you will be required to perform and thoroughly document your data and calculations. Be sure to record all observations and any relevant notes that you think you will need to include in your laboratory report; refer to the end of this document for information that must be included in your final report.
Procedure: Preparing the Lab IFrom the course home page, access the lab environment by clicking on the Virtual Lab link.After the lab environment loads, click ‘File’ then ‘Load an Assignment.’Select the ‘Thermochemistry’ category.Select the ‘Heats of Reaction’ assignment.Review the data table for this lab (see the end of this document).Evaluate the reactions shown in the ‘Background’ section above and draft a hypothesis based on this information; write your hypothesis in your notes for reference later.At this point, you have prepared the laboratory for the experiment with the required supplies to complete your experiments.In the ‘Glassware’ menu, place a 50-mL graduated cylinder and a foam cup onto the workbench. From the ‘Tools’ menu, add a balance (scale) to the workbench. Then, move the distilled water and solid NaOH to the workbench as well.Transfer 50.0 mL of distilled water to the foam cup. To do this, you must first transfer the water to the graduated cylinder then to the foam cup. After dragging the water to the graduated cylinder, enter ‘50.0’ and click ‘Pour.’ Record the initial temperature of the water in your data table.Tare the balance after adding the foam cup, then weigh 1.00 g of solid NaOH pellets directly into the foam cup. Remove the scale from the workbench at this point.Pour the entire contents of the graduated cylinder into the foam cup and immediately record the highest temperature observed and the mass of the contents of the cup. In a real laboratory, you have a temperature probe (like a thermometer) inserted into the foam cup to record the maximum temperature.Take the 0.50 M HCl solution, a foam cup, the solid NaOH, a 50-mL graduated cylinder, and a balance from the from the Stockroom and place it on the workbench.Repeat Steps 7-10 but replace the 50 mL of water with 50 mL of the 0.50 M HCl solution. After mixing the HCl solution with the solid NaOH, immediately record the highest observed temperature.Clear the workbench.Take out another graduated cylinder, a fresh foam cup, the 1.0 M HCl and 1.0 M NaOH solutions and add them to the workbench.Measure 25.0 mL of the 1.0 M HCl solution into the foam using the graduated cylinder. Using a clean graduated cylinder (to avoid cross-contamination), measure out 25.0 mL of the 1.0 M NaOH solution.Pour the NaOH solution into the foam cup and immediately record the highest observed temperature.Clear the workbench.Complete the table shown below in the ‘Data’ section by filling in the values recorded during the experiments or those produced from the required calculations.Write out the net ionic equations for all three reactions referring to the initial reactions shown in the ‘Background’ section of this template. Be sure to use proper notation when writing your equations as you will include these in the final draft of your report.The energy, x1, in Reaction 1 represents the energy of solution for one mole of solid NaOH. Look at the net ionic equations for Reactions 2 and 3, and make a similar statement concerning the significance of x2 and x3 and their connection to Hess’s law. Record your statements in the ‘Notes’ section below for review later.Find the difference between the value of x2 and the sum of x1 plus x3.; let x4 be equivalent to the sum of x1 and x3and let x5 be the difference between x2 and x5. This calculation scheme is shown below. Make notes about any similarities or differences between the values in your notes.x4 = x1 + x3x5 = x2 – x4Calculate the percent difference between x2 and x4 according to the equation below. (Assume x2 to be the accepted value.) Record the calculation in your notes.Performing the Reactions IPerforming the Reactions IIPerforming the Reactions IIIData Analysis
NotesThis section should include notes about any observations or data collected during the lab.Begin typing here.DataThis section will include all data collected during the lab.Thermochemical Data Tinitial (°C)Tfinal (°C)ΔT (°C)moles NaOHqreaction (kJ)ΔHrxnReaction 1Reaction 2Reaction 3*Note: You can copy and paste your data table into your report later.Insert the net ionic equations here:Reaction 1:Reaction 2:Reaction 3:Report RequirementsThis section contains key information that must be included in your typed report.Define the problem/goals in a manner that is clear and insightful.Identification of the strategies/procedures used during the lab.Clear hypothesis statement and other potential solutions that identify any relevant contextual factors (i.e. real-world costs). Consider alternative ways to confirm Hess’s law experimentally.Clear presentation of data including any tables or other figures that are relevant to understanding your stated conclusions at the end of the report. The following items are required in your report:Data tableNet ionic equationsPercent difference calculation.Clearly stated results (evidence confirming Hess’s law) and discussion possible improvements to the procedure.Conclusive statements arguing in favor of your findings.Note: All reports will be graded using the rubric embedded within the course.Here are some questions to consider as you write your report:Does my problem statement make sense?Have I summarized my strategies/procedures well enough to be replicated by an outsider?Did I have a valid hypothesis at the start of the lab? Have I expressed this in my report?Do my tables and/or graphs make sense?Are my conclusions valid based on my supplied data?Did I thoroughly summarize my laboratory experience in a concise, factual way such that the reader can understand my processes and findings in the conclusion section alone?
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