MiniLab: Limiting reagents versus Excess reagents • Title: The effect of the amount of reagent on the amount of product produced. Background: Acetic acid reacts with sodium bicarbonate according to the reaction: CH3COOH + NaHCO3 --> NaCH3COO + CO2 + H2O • According to the balanced equation, one mole of acid reacts with one mole of sodium bicarbonate.
Problem Statement • Which reagent is the limiting reactant for three different scenarios?
Hypothesis • Predict, which balloon will inflate the most? Please use the title and problem statement to come up with a hypothesis. (if, then, because)
Variables Independent variable – the amount of baking soda (NaHCO ) : 2 g, 3.5 g and 5 g. Dependent variable- the amount of gas produced (CO ) Control (constant) – amount of vinegar used (CH COOH)
Materials • 250-mL Beaker 3 250-mL Erlenmeyer flask • 3 large balloons • 150 mL vinegar • Balance scale • Weighing paper • 15 g sodium bicarbonate (baking soda) • Spoon • Measuring tape
Procedures • 1. Weigh three portions of sodium bicarbonate: A-2.0 g; B-3.5 g; and C-5.0 g. • 2.Transfer each portion to a balloon using a spoon. • 3.Use a marking pen to mark the balloon with the mass of sodium bicarbonate added. • 4.Place 50 mL of vinegar into each of the three 250-mL Erlenmeyer flasks. • 5.Attach a balloon containing a pre-weighed amount of sodium bicarbonate to each of the three flasks. • 6.Lift each balloon so as to add the sodium bicarbonate to each flask. • 7. Observe the result. Note the apparent amount of gas produced. Note the appearance of the material inside each flask.
Data Analysis 1. Define limiting and excess reagents. 2. How is the amount of product in a reaction affected by an insufficient quantity of any of the reactants (reagents) 3. What was the limiting reagent in the reaction? Explain. 4. What was the excess reagent in the reaction? Explain. 5. Which balloon was the largest? Explain. 6. Which balloon was the smallest? Explain. 7. Rust is produced when iron reacts with oxygen. How many grams of Fe2O3 are produced when 12.0 g of iron rusts? 4Fe(s) + 3O2(g) → 2Fe2O3(s)
Conclusion – Paragraph 1 • The title of the lab is, The Effect of the Amount of Reagent on the Amount of Product Produced. The purpose of the lab was to determine which reactant was the limiting or excess reagent. The two reactants are vinegar and baking soda. In this lab different amounts of baking soda was placed in three separate balloons. The amount of vinegar used was 150 ml. Each of the three flask used contained 50 ml of vinegar. The balloons with the various amounts of baking soda was placed over the mouth of each of the three flask. The balloons were then flipped over, so that the baking soda from the balloons will combine with the vinegar in each flask. The balloons inflated, which indicated that a gas was produced in the reaction. 10 points
Conclusion-Paragraph 1 • The hypothesis that was tested is, • The independent variable in the lab is the different amounts of baking soda. The dependent variable is the amount of gas produced based on the size of the balloons. The constant in the lab is the amount of vinegar that was placed in each flask.
Conclusion – Paragraph 2 • The answers to the analysis questions combined in a cohesive manner. Complete sentences. • Do not include #7. 10 points
Conclusion-Paragraph 3 • Was the hypothesis supported? Explain. • What real-life applications can this concept of limiting and excess reagents be applied to? 10 points