Procedure

Experiment 1

1.      I took a clean crucible, balance, and a Bunsen burner and put them on my work station


2.      I then took the crucible and placed it on the balance and recorded the mass of the crucible (88.000 g)

3.      I added 10 g of copper to the clean crucible, then weighed the new mass of the crucible and the copper (98.000 g)

4.      I then took the Bunsen burner and heated the crucible with the copper contents inside at a very low temperature.

5.      I set a timer for 60 seconds and recorded how long it would take for the copper to react with the oxygen in the air

6.      I then removed the crucible from the Bunsen burner to cool, then weighed the crucible and the copper once more

7.      The total mass increased to 100.518 g

8.      After I recorded my masses and documented my reactions, I cleaned and cleared my work station.

 

Experiment 2

1.      I took a 50 mL beaker and weighed it on the balance to record the mass (85.000 g)

2.      I then moved the beaker onto the workbench and added 5 g of copper sulfate pentahydrate

3.      Weighing the beaker and the content, the new mass of the beaker was 90.000 g

4.      I then was able to dissolve the copper sulfate pentahydrate by adding 30 mL of water to the beaker

5.      I then added 10 mL of 6M sodium hydroxide to the beaker and watched as the color changed from blue back to white. The new mass was now  131.273 g

6.      Getting a new clean beaker, I then poured the solution from my first beaker into the new beaker, leaving the solid content in the original beaker

7.      I then went and got a test tube and weighed it (27.400 g)

8.      I then took the solid content from the original beaker and put it into the test tube

9.      I then took the Bunsen burner and heated the test tube with the solid content for 30 seconds

10.  Observing the test tube the solid decomposed into copper oxygen in the air and water was released into the air as water vapor. The contents in the test tube changed from blue to black letting me know that the reaction is complete

11.  I then moved the test tube on the work station to cool

12.  I then weighed the test tube and record the mass (28.993 g)

13.  After I recorded my masses and documented my reactions, I cleaned and cleared my work station

 

Data

Experiment 1

 

1.      Record and calculate the following for the copper:

 




2.      Calculate the following for the oxygen:

 

 

 

 

 

 

 

 

 

 

Abstract (5 points)

[Instruction: One paragraph (~75 – 100 words) summarizing the purpose of the experiment, statement/sentence describing the method of measurement, primary findings and their significance.]

 

The purpose of this experiment was to determine the empirical formula of a compound experimentally, by first finding the mass of the element in the compound, then by converting the mass to number of moles for the element in the compound using its molar masses. To obtain the number of moles, I used the formula  By using the empirical formula for this lab, I was able to find the number of moles of an element in a compound. Where n is the number of moles, m is the mass of the element, and MM is the element’s molar mass. Once this had been completed, I could distinguish the ratio between the two. Thus, discovering the simplest ratio of an element.

 

 

 

 

 

 

Introduction (15 points)

[Instruction: A ~2 paragraph full section including a detailed description of the physical or chemical effect explored through the experiment, a description of the exact physical or chemical systems that were studied, theory or competing theories associated with the experiment, physical and chemical relevance and applications, a non-technical description of the measurement method (but not a technical description of the experimental design – that belongs in the next section!). Equations should be limited to introducing or explaining critical primary relationships and terminology.]

 

 

 

 

 

 

 

 

Experimental Methods (10 points)

[Instruction: A brief ~2 paragraph technical overview of the experimental apparatus and a past tense technical description of experimental procedures. The latter should be given in paragraph form, communicate what was performed, but not as a moment-by-moment recount of your lab activity (and not copied verbatim from the lab manual).]

 

     This experiment utilized the empirical formula of copper oxide by using two methods. In the first experiment, I heat dried copper powder until it fully reacted with oxygen from the air to form copper oxide. In the second experiment, I recorded how an aqueous solution of copper (II) sulfate (CuSO₄) with sodium hydroxide (NaOH) to form copper (II) hydroxide reacted to form a precipitate. I used a Bunsen burner to heat the precipitate until it decomposed into water vapor and copper oxide. Copper Oxide is able to be made by two different methods as explored in this lab, while maintaining the same empirical formula. In the first part of this experiment I gathered information to calculate and compare the molar ratio of the moles of copper oxide vs. the moles of oxygen in the copper oxide. I utilized the empirical formula to obtain my results.  The moles of both copper and copper sulfate was 0.1574. The moles of oxygen was 0.1574 moles as well. According to this discovery of the molar ratio, the empirical formula of copper oxide is CuO.

 

In order to fully obtain an understanding of the experiment, I had to then calculate the moles of Cu in copper sulfate which was 0.02003 moles. The moles of oxygen in the copper oxide, was also calculated and respectively was determined to be 0.02 moles. Once I had these calculations, the molar ratio between copper vs. oxygen was divided by the moles of copper, then by moles of oxygen. I was surprised to see that the ratio was 1:1. The experiment called for the simplest ratio, which was determined to be 0.02003 moles/0.02 moles, when further simplified, it became 1.002 moles/1 mole which is approximately a 1:1 ratio. Therefore, the empirical formula of copper oxide is CO. The percent was also calculated by subtracting the expected moles by the actual moles and then dividing that by the expected moles. Based on the result, there was a significant difference, but rather small of 98%.

 

 

 

 

 

 

 

 

Results/Analysis (25 points)

[Instruction: Organize and communicate your results that have been recorded in the Lab Notes section of the Late Nite Labs lab session, with appropriate graphical and tabular presentation, and describe calculations needed to derive and interpret your numeric results and their error. As the report is a written document, use text to describe analysis procedures, indicate what is presented in figures and tables, and to comment on or point out notable trends.

 

Remember to pay attention to significant figures and record all masses and volumes with all the decimals provided by the lab.]

 

 

 

 

 

Discussion (40 points)

[Instruction: A multi-paragraph section that accomplishes the following:

-          Restates your primary numeric results from the results/analysis section.

-          Puts your results in context by responding in paragraph form to the calculations in the Short Answer Questions in this section.

-          Discuss any possible sources of error in your experiment and put them in context with your results.

-          Complete the Short Answer Questions in this section.]  

 

       I.            Discussion (20 pts.):

 

 

 

 

 

 

 

 

    II.            Short Answer Questions (20 pts.):

 

Experiment 1: Synthesize Copper Oxide from Copper

 

Q1: In this experiment, how much mass did copper gain during heating? (1 pts.)

 

 

 

Q2: What is the balanced equation for the copper oxide formation? (1 pts.)

 

 

 

Experiment 2: Synthesize Copper Oxide from Copper (II) Sulfate Pentahydrate

 

Q3: In this experiment, how many moles of copper were in the copper oxide formed? The molar mass of copper (II) sulfate pentahydrate is 249.68 g/mol. For best accuracy, use the mass measurements read using the balance. To receive full points for this question, list every step of your calculation. (3 pts.)

 

 

 

Q4: Calculate the mass of oxygen in the copper oxide. The molar mass of copper is 63.55 g/mol and the molar mass of oxygen is 16.00 g/mol. To receive full points for this question, list every step of your calculation. (3 pt.)

           

 

 

Q5: Calculate the number of moles of oxygen in the copper oxide. The molar mass of oxygen is 16.00 g/mol. To receive full points for this question, list every step of your calculation. (2 pts.)

 

 

 

Q6: Calculate the molar ratio between copper and oxygen. To receive full points for this question, list every step of your calculation. (2 pts.)

 

 

 

Q7: According to the molar ratio, what is the empirical formula of the copper oxide? (1 pt.)

 

 

 

 

Q8: Similar to copper, magnesium also reacts with the oxygen in the air when heated to form magnesium oxide. Given the experimental data in the table below, what is the empirical formula of magnesium oxide? The molar mass of magnesium is 24.31 g/mol and the molar mass of oxygen is 16.00 g/mol. To receive full points for this question, list every step of your calculation.

 

 

(4 pts.)

 

 

 

 

 

Q9: The reported molar mass for the copper oxide formed in experiment 1 is 79.55 g/mol. What is the molecular formula of the oxide formed in experiment 1? The molar mass of copper is 63.55 g/mol and the molar mass of oxygen is 16.00 g/mol. To receive full points for this question, list every step of your calculation. (3 pts.)

 

 

 

 

Conclusions (5 points)

[Instruction: A final paragraph that summarizes the following: your numeric findings; comparisons to literature values and theory; a summarizing conclusion about the most significant sources of experimental error for your experiment; what the primary experimental results reveal about the physical or chemical properties or effects examined and significance to physical or chemical applications.]

 

 

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