Experiment #8: Limiting Reactant

This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.

We then proceeded in testing for excess Ca2+ by adding two drops of .5 M K2C2O4 to test tube two and attentively observed to see if a precipitate formed, which it did. This meant that Ca2+ was in excess and C2O42- was the limiting reactant in the original salt mixture. We then cleaned up. Upon returning to our next class, we took the filter paper, with the precipitate on it, and took its mass.

Gilbert, John and Stephen F. Martin. Experiment Organic Chemistry: A Miniscale & Microscale Approach. Belmont, CA: Thomson Brooks/Cole, 2010. 537-547. Print.

Purpose: The purpose of this experiment is to observe a variety of chemical reactions and to identify patterns in the conversion of reactants into products.

Finally ensure that your results are accurate. You should have a light blue precipitate remaining when the sodium carbonate reacts with the copper chloride and when sodium sulphate ionises with copper chloride no precipitate should have formed.

This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.

Abstract: This experiment introduced the student to lab techniques and measurements. It started with measuring length. An example of this would be the length of a nickel, which is 2cm. The next part of the experiment was measuring temperature. I found that water boils around 95ºC at 6600ft. Ice also has a significant effect on the temperature of water from the tap. Ice dropped the temperature about 15ºC. Volumetric measurements were the basis of the 3rd part of the experiment. It was displayed during this experiment that a pipet holds about 4mL and that there are approximately 27 drops/mL from a short stem pipet. Part 4 introduced the student to measuring

The limiting reactant of a chemical reaction is the substance that places an upper bound on the amount of product that the reaction can produce. The limiting reactant places this upper bound because the reaction must stop once all of the limiting reactant is consumed.

This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.

In this experiment, the limiting reactant of all trials was the magnesium while the excess reactant was the hydrochloric acid. This means that, in this reaction, the magnesium is used up completely first, leaving extra hydrochloric acid behind. This was found through stoichiometry, as the reactants were converted into each other through mass-mass calculations. As such, through stoichiometry, it was discovered that magnesium was the limiting reactant as 2.5 grams of magnesium requires 7.5g or 7.5ml (Note: 1g = 1ml) of hydrochloric acid to react. On the other hand, 50g of hydrochloric acid requires approximately 17g of magnesium to react, which is far from the original amount had. Likewise, if 2.5g of magnesium, the largest amount of magnesium

Dictionary of organic compounds, 6th edition, Chapman and Hall, London, Volume 3(& Volume 6), 1996 Maria Lindsay and Sean P. Hickey, Organic chemistry lab 2 manual, department of Chemistry University of New Orleans

Fifield, F. W. and Kealey, D. 1995. Principles and Practice of Analytical chemistry. (4th ed) Glasgow, Blackie Academic and professional.

The volume of carbon dioxide gas produced from a reaction was measured in order to determine what carbonate sample was used. A gas assembly apparatus was used to capture the gas from a reaction between an unknown carbonate and 6M hydrochloric acid; three trials were performed. The mass of the unknown carbonate was determined, and the reaction occurred in a test tube. The volume of gas produced by the reaction was measured, and the partial pressure of carbon dioxide was calculated after the partial pressure of water vapor was determined using Dalton’s Law of Partial Pressures. The percent mass of carbon dioxide gas was then calculated, and the average mass percent was compared to the table of known carbonates. It was concluded that the unknown carbonate sample used in the reaction was magnesium carbonate.

In a chemical experiment when two substances are reacting, one reactant will be consumed first then the other one and it will be call Limiting reactant. “The limiting reactant is a reactant in a chemical reaction that determines the amount of product produced” (Helmenstine). This is the substance that controls the results, depending on the amount that it can produce it’s going to be determinate how far the chemical reaction can go. The Percent Yield gives the amount of product that could possibly be produced in a given reaction. Percent yield measures how efficient the reaction is under certain conditions.” Percent yield measures how efficient the reaction is under certain conditions” (Boundless). To find the Percent Yield, we have to calculate

6. The precipitate may have not dried up properly making it so there was water adding weight on it.