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The Determination of a Chemical Formula

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❶Measure and record the mass of the cool crucible of your copper chloride sample.

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Introduction
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Objectives

Plastic beakers should never be used with heat. Decant pour the clear liquid into a 50 mL beaker. When all that remains in the original beaker are the copper plated washers, rinse the washers with distilled water and decant the remaining liquid, being careful not to lose any copper, into a container. This water can be disposed of down a sink drain. Repeat this process three times. Remove the first washer and use the stir stick to scrape the copper into the metal cupcake wrapper. Rinse the washer with distilled water to be sure all copper is recovered into the wrapper.

Repeat the process for the second washer, scraping the copper into the same wrapper. Monitor the wrapper and contents and use a hot pad or towel to carefully remove them from the oven after 45 minutes, or after all of the water has evaporated. After the wrapper has cooled to room temperature, empty the dried copper from the wrapper onto the scale and weigh the final mass. Create a pie chart showing the percent composition for each element in the compound copper gluconate, clearly label each element and the percentage.

Why is it important in this experiment to be accurate in all your measurements? List the measurements you will take in this experiment. What chemical wastes are produced in this reaction? Record the mass in the Data section below.

Mass of copper gluconate initial, see Step 2: What is the chemical formula of copper gluconate? List two sources of error in the experiment and explain the impact they had on the results. When we first began transferring the copper we started by scooping it out of the beaker.

This could have resulted in the loss of some of the copper, causing the percent error to be high. It would have been higher if it weren't for our realization that we were supposed to pour the entire beaker onto the filter paper in the funnel.

Data Analysis How many moles of water were in your sample of copper chloride hydrate? Based off of our results: Obtain and wear goggles 2. Measure and record the mass of a clean, dry crucible without cover. Obtain about 1 gram of the unknown copper chloride hydrate and place it in the crucible.

Use a spatula to break up any large pieces of the substance by pressing the pieces against the wall of the crucible. Measure and record the mass of the crucible with compound. Set up a ring stand, ring, and clay triangle for heating the sample. Rest the crucible on the clay triangle.

Set up a lab burner and ignite the burner away from the crucible. Adjust the burner to get a small flame. Data Table Mass of crucible g Hold the burner in your hand and move the flame slowly back and forth underneath the crucible to gently heat the sample.

Do not overheat the compound. Note the color change, from blue-green to brownish, as the water of hydration is driven out of the crystals. When the sample has turned brown, gently heat the crucible for two more minutes.

Remove and turn off the burner. Cover the crucible and allow the sample to cool for about ten minutes. Remove the crucible cover and inspect your sample. If you see any blue-green crystals, reheat the sample until the crystals have turned brown. Measure and record the mass of the cool crucible of your copper chloride sample. Transfer the brown solid to a clean and empty 50 mL beaker.

Rinse out the crucible with two 8 mL aliquots of distilled water and pour the water into the 50 mL beaker. Gently swirl the beaker to completely dissolve the solid. Note that the color of the solution is green as the copper ions are rehydrated. Measure out about 20 cm of aluminum wire, coil the wire, and place the wire in the beaker of solution so that it is completely immersed in the copper chloride solution. Note that the reaction produces a gas, elemental copper is forming on the surface of the aluminum wire, and the color of the solution is fading.

The reaction will take about 30 mins to complete. When the reaction is done, the solution will be colorless. Most of the elemental copper will be on the aluminum wire. Add 6 drops of 6 M HCl solution to dissolve any insoluble aluminum salts in the mixture, which should make the solution clear.

Use a glass stirring rod to scrape off as much copper as possible from the Al wire. Slide the wire up the wall of the beaker up and out of the solution with the glass stirrer and rinse off any remaining copper with distilled water. Put the Al wire aside.


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Lab burner beaker Funnel Filter paper Unknown solid copper chloride hydrate Aluminum wire, 20 gauge 6 M hydrochloric acid, HCL, solution 95% ethanol solution Distilled water Wash bottle Balance Glass stirring rod 5. Remove and turn off the burner. Cover the crucible and allow the sample to cool for about ten minutes. 6.

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In expressing the formula of a hydrated crystal like this one, because the water molecules remain intact, we indicate the number of water molecules incorporated into the crystal (per formula unit) with the nomenclature ⋅zH 2O, rather by than adding H .

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The Determination of a Chemical Formula John Dalton was an Englishman, a teacher, and an exceptional theoretical chemist. He developed and wrote the modern atomic theory at the turn of the 19th century (documents point to ). He was influenced by the experiments of two Frenchmen, Antoine Lavoisier and Joseph Louis Proust. Lab Report #4: Determination of a chemical formula: the empirical formula of Magnesium Oxide 1. Purpose: Determine the empirical formula of magnesium oxide from the percent composition (this can found using the Analytical Method and the Synthesis Method).

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DETERMINATION OF A CHEMICAL FORMULA LAB ADV COMP 1 From Advanced Chemistry with Vernier, Vernier Software & Technology, INTRODUCTION John Dalton was an Englishman, a teacher, and an exceptional theoretical chemist. He developed and wrote the modern atomic theory at the turn of the 19th century . Introduction: In order to determine the chemical formula of a compound of the molar ration in the compound must be determined first by finding the mass. In this experiment the compound that was used was copper chloride hydrate%(6).