Lab Report Limiting Reactant PDF

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Limiting Reactant By: Jonathan Pilafas (performed on 10/8/2018)

Purpose: The objective of this lab is to determine the percent composition of the given and unknown solution.

References: 1. “Laboratory Experiments for Chemistry 121” - Harper College 2. http://dept.harpercollege.edu/chemistry/msds1/Trisodium%20phosphate.pdf 3. http://dept.harpercollege.edu/chemistry/msds1/Zinc%20Sulfate%20heptahydrate.pdf 4. http://dept.harpercollege.edu/chemistry/msds1/Nitric%20Acid%20fuming%20JTBaker.pd f 5. https://www.americanelements.com/zinc-phosphate-7779-90-0 Reagents: Name

Formula

Molecular Weight

Concentration

Hazards

Trisodium Phosphate

Na3PO4

163.94 g/mol

N/A

Health - 3 Fire - 0 Reactivity - 0

Zinc Sulfate

ZnSO4

161.47 g/mol

N/A

Health - 2 Fire - 0 Reactivity - 0

Nitric Acid

HNO3

63.01 g/mol

68%

Health - 4 Fire - 0 Reactivity - 3

Zinc Phosphate

Zn3(PO4)2 (product)

386.11 g/mol

N/A

Health - 1 Fire - 0 Reactivity - 0

Methods: To begin the experiment, obtain the unknown mixture, record the unknown number listed on the mixture, and mass between 1.9g - 2.1g of this mixture. Next, add 200 mL of water to a 400 mL beaker and add 6 moles of nitric acid to bring the pH level to 5-6. After this, transfer the unknown to the beaker while keeping the pH level at 5-6. Next, stir the solution for one minute and let it settle. Use a watch glass as a flame cover and boil the solution for 30 minutes. Begin heating the deionized water as well, and pour two 15-25 mL volumes into two clean beakers. In addition, label and mass a watch glass and filter paper. Place the filter paper in the funnel and transfer the precipitate to the funnel. Wash the precipitate on the paper with hot water. Suction for 1-2 minutes after the filter is completed, and remove the paper to transfer it to the watch glass using a spatula. Mass the glass and the filter paper and record the data Add 10 drops of 0.5M sodium phosphate to the beaker and record the data found. In addition, add 10 drops of 0.5M of zinc sulfate to the beaker and record the data found. Lastly, identify the limiting/excess reactants. To begin the experiment, collect appropriate amounts of sodium carbonate, hydrochloric acid, sodium chloride, potassium hydroxide, magnesium nitrate, copper (II) nitrate, potassium hydrogen carbonate, silver nitrate, sodium iodide, strontium nitrate, potassium iodate, sulfuric acid, calcium chloride. Combine various combinations of these solutions as guided in the list below. Balanced Chemical Equation: 3ZnSO4 (aq) + 2Na3PO4 (aq) → 3Na2SO4 (aq) + Zn3(PO4)2 (s)

Observations:

Trial 1

Trial 2

Beaker 1

Cloudy precipitate

No Reaction

Beaker 2

Cloudy precipitate

No Reaction

Unknown #

Trial 1

Trial 2

Mass of Sample

3.149 g

3.058 g

Mass of Product

0.924 g

0.833 g

Data:

Conclusion: As a result of this lab, I have concluded that reactions are made when certain reactants of mix with other reactants. Reactions are made when observing the combinations of Sodium carbonate and hydrochloric acid, Sodium carbonate and copper(II)nitrate, Potassium hydrogen carbonate and hydrochloric acid, Silver nitrate and sodium iodide, Potassium hydroxide and hydrochloric acid, Strontium nitrate and potassium iodate, Strontium nitrate and sodium carbonate, Sodium carbonate and sulfuric acid, Sodium hydroxide and copper(II)nitrate. In addition, reactions do not exist when observing the reaction between sodium chloride & sodium carbonate, potassium hydroxide & magnesium nitrate, and silver nitrate & sodium chloride.

Calculations: 1. 3ZnSO4 (aq) + 2Na3PO4 (aq) → 3Na2SO4 (aq) + Zn3(PO4)2 (s) Mass of ZnSO4 = 2.003 g (2.003 g ZnSO4 / 1) X (1 / 161.44 g/mol ZnSO4) X (3 mol ZnSO4 / 3 mol Na2SO4) = 0.01241 moles Na2SO4 → Excess Reactant Mass of Na3PO4 = 1.972 g (1.972 g Na3PO4 / 1) X (1 / 163.94 g/mol Na3PO4) X (2 mol Na3PO4 / 3 mol Na2SO4) = 0.008019 moles Na2SO4 → Limiting Reactant Limiting Reactant = Na3PO4 2. (0.01203 moles Na3PO4 / 1) X (3 mol ZnSO4 / 2 mol Na3PO4) = 0.01804 mol ZnSO4 (0.01804 mol ZnSO4 / 1) X (161.44 g ZnSO4 / 1 mol ZnSO4) = 2.9124 g ZnSO4 Since is the limiting 3. F 4. F 1.

Determine which reactant is the limiting reactant

2.

Calculate the mass of the limiting reactant consumed in the reaction.

3.

Calculate the total mass (i.e. not just what is in excess) of the excess reactant

in the original mixture. 4.

Calculate the % by mass of ZnSO4 and Na3PO4 in the original mixture.

5.

Calculate an average % by mass of ZnSO4 and Na3PO4 in the original mixture.

Discussion 1.

Report the unknown number of your mixture.

2.

What was your limiting reactant? How did you determine this?

3.

Compare the results obtained from both trials.

4.

Report an average % by mass of ZnSO4 and Na3PO4 in the original mixture.

***Technique matters! One extra credit point will be awarded to students whose % by mass of ZnSO4 and Na3PO4 come within 2 % points of actual values.

Conclusion...