Stoichiometry Lab Report Limiting Reagent

Theoretical Yield: The amount of the product obtained when all of the limiting reagent react.

Stoichiometry is a very important part of chemistry. Stoichiometry refers to calculating the masses of molecules and their products . The reactants are usually given and stoichiometry is used to find the products of the equations as well balancing the equation. An example of this would be sodium chloride (NaCl). Stoichiometry will say that if there are ten thousand atoms of sodium and one atom of chlorine, only one molecule of sodium chloride can be made and that fact can never be changed.

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.

In Experiment B the limiting reactant was determined to be CaCl2 when two drops of the test reagent 0.5 M CaCl2 was added to the supernatant liquid in test tube 1, and a precipitate formed. Since there was a reaction, there was C2O42- in excess and Ca2+ is the limiting reactant in the original salt mixture present in test tube 1 . This was further confirmed when two drops of the test reagent .05M K2C2O4 was added to the supernatant liquid in test tube 2. There was no precipitate because Ca2+ was not present since it was the limiting reactant and instead C2O42- was in excess.

Usually, the percent is a good amount less than 100 because of multiple factors including transfer between different lab tools and when an unfulfilled reaction takes place. In the case of this experiment, copper most likely was lost between transfers of the Copper (II) solution, although loss was attempted to be minimized. Also, after the reaction, the copper was filtered and some mass could have lost if the reaction was not fully carried out and all of the copper did not precipitate out of the solution. But, when the copper oxidized overnight on the heater, the reaction with oxygen added mass to the ending mass of copper. These areas of losing and gaining mass throughout the procedure equaled out in the end because the percent yield was very close to 100% as the actual yield was 0.7 grams of copper and the theoretical yield was 0.71 grams of copper. If the copper did not oxidize, it is believed that the percent yield would not have been as close to 100% as it was because the oxygen gave mass back that was lost along the way of the

Aim: The aim of the lab “Chemical Equilibrium” is to observe the effects of changes in concentrations of products and reactants on the position of the equilibrium of given chemical reactions.

Question of the day: What is the stoichiometric ratio of reactions in the chemical synthesis of the (2, 4-pentanedianato) iron (III) complex ion?

The purpose of this lab was to determine the limiting reactant in a reaction between copper sulfate and iron. Using the reaction between copper sulfate and iron, the reaction was observed to see the reaction and transformation of matter. The copper sulfate was placed into a beaker, as the excess reactant, then iron filings added until the heated solution was completely reacted. This reaction created an excess of leftover. The law of conservation of mass can be observed in this reaction, and using the data found, the percent yield calculated.

Using elemental analysis to determine the percent mass composition of each element in a compound is the first step in creating an empirical formula. There are many different types of elemental analysis, but in this experiment gravitational analysis and Beer’s Law are used. Elemental analysis is first used to find the moles of each element, then converted to mass, and then the percent mass of the element in the product is found (2).

The study of the quantitative relationships between the amounts of reactants used and the amounts of products formed by a chemical reaction is called stoichiometry.

If the relative amount of reactants is altered, then the limiting reactant may change accordingly. For example, a balanced chemical equation of a certain reaction specifies that an equal number of moles of two substances A and B is required. If there are more moles of B than of A, then A is the limiting reactant because it is completely consumed when the reaction stops and there is an excess of B left over.

Stoichiometry is a method scientists use to presume how two or more substances will react together. In order to do so successfully, the reactants are positioned on the left and the products on the right. The most important part of successfully

Stoichiometry has many uses in the real world. In the chemical industry and in professional scientific experiments, scientists use stoichiometry to save money. Scientists use stoichiometric calculations to determine the amount of a substance they need to purchase for a specific reaction. There are four possible reactions that can occur when sodium bicarbonate thermally decomposes. In this lab, stoichiometry was used to find out which balanced chemical equation out the four best represents the thermal decomposition of sodium bicarbonate.

Chemical equilibrium is the study of change within a chemical reaction and how far it will go to reach a dynamic equilibrium (Burdge). Dynamic equilibrium is defined as the constant movement of species in a chemical reaction, gone to incompletion while the rates of production and consumption are equal (Kf = Kr ) (Burdge). It differs from static equilibrium in that species are constantly being consumed and produced, it is dynamic movement (Fox). The concentration of such species do not change, it remains constant (Fox). The rate at which species are being consumed and produced is known as the equilibrium constant (K) (Burdge). Due to the fact that the concentration

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