lab 9

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Glendale Community College *

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130

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Chemistry

Date

Jul 3, 2024

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docx

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CHM130LL Lab 9 – Stoichiometric Analysis 42/100 Complete the following items by typing into the text box provided. The boxes will increase in size if additional space is necessary. Please be sure to save all your work as an MS Word document to submit properly. A. Data Table: Complete the Data Table using data taken from the photos provided. (6 pts) Item Measured/ Quantity Calculated Mass (grams) Iron nails (before reaction) 7.75g Iron nails (after reaction) 5.50g Mass of iron consumed 2.25g Initial mass of filter paper (before filtration) 0.86g Mass of filter paper and solid product 3.52g Mass of solid product 2.66g B. Calculations: 1. Determine the mass of iron consumed in the reaction. Show your work. (4 pts) Formula : massof ironconsumed = initial massof iron − finalmassof iron 7.75g – 5.50g = 2.25g 2. Calculate the number of moles of iron consumed using dimensional analysis and the molar mass of iron as a conversion factor. Show your work. (10 pts) 2.25g iron x 1mol iron/ 55.85g iron = 0.0402 = 4.02 x 10^-2 mol iron consumed Great job showing your work and paying attention to significant figures. 3. Determine the mass of copper formed. Show your work. (4 pts) Formula : massof copper formed = mass of filter paper ∧ copper − massof filter paper 3.52g – 0.86g = 2.66g 4. Calculate the number of moles of copper formed using dimensional analysis and the molar mass of copper as a conversion factor. Show your work. (10 pts) 2.66g copper x 1 mol copper/ 63.55g copper = 0.0419 = 4.19 x 10^-2 mol copper formed Scientific notation is a great way to show this answer.

5. What is the experimental mole ratio between the iron and the copper? Determine the simplest whole number ratio of moles of iron consumed (see Question 2), to moles of copper formed (see Question 4). [Note: To find the ratio, you must use your answers to Question 2 and Question 4 and divide both values by whatever value is smaller.] (8 pts) 0.0402 mol Iron/ 0.0402 mol Iron = 1 0.0419 bol Copper/ 0.0419 mol copper = 1.04 = 1 Ratio = 1:1 Thank you for following the directions and providing a whole number ratio. C. Analysis Questions: 6. What color was the 1 M CuCl 2 ·2H 2 0 solution before the nails were placed in it? What ion was responsible for this color? Explain your reasoning with support from the lab. (8 pts) -8 points 7. After the nails were allowed to react, did the solution change color? What was responsible for this color change? Explain your reasoning with support from the lab. (8 pts) -8 points 8. What type of chemical reaction was this? You need to determine the type of reaction and explain how you know it falls into that category. (8 pts) -8 points 9. What was the solid product that formed on the nails? Explain your reasoning with support from the lab. (8 pts) -8 points 10. Based on the experimental mole ratio, which of the following equations is MOST LIKELY to be the one represented by this experiment? Justify your answer with support from the lab. (9 pts) -9 points

11. Why is knowing the “mole ratio” essential when performing stoichiometric calculations? Your response must include (a) a discussion of balanced equations in the context of the law of conservation of mass (8 pts) and (b) an example different from the one in this lab that shows how a mole ratio is used in a stoichiometric calculation (9 pts). -17 points

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