Define stoichiometry

This is conducted in an open lecture style. Students are allowed to ask questions at any time and encouraged to contribute any answers or comments they have. Usually this is done in 45 minutes and no special equipment is needed. Please stress that solving stoichiometry problems depends on having a balanced chemical equation! Because this is lecture based, it can be modified to fit in any classroom environment. Description and Teaching Materials Begin the class by providing a list of ingredients needed to make a cake (I usually just put this on the board). Then, ask the students to write down every possible combination of ratios within this recipe. For example, 1 box of cake mix is needed for every two eggs. Once they have completed this, explain that they just completed mole ratios for the basic chemical equation of making a cake. Continue by giving them a simple chemical equation and have them find all the combinations of ratios. Once they have completed this you can begin notes on mole ratios and how they pertain to stoichiometry. This is where a definition of stoichiometry is given and we go through more problems until students are comfortable with the concept of stoichiometric calculations. Teaching Notes and Tips Students should have a firm background in conversion factors and balancing equations. They should also know the basic idea of a ratio. Sometimes it is nice to add a hands on demonstartion of making cake batter or even better, something they can eat after maki...

\( \newcommand\) • • • • • • • • Learning Objectives • Define stoichiometry. • Relate quantities in a balanced chemical reaction on a molecular basis. Consider a classic recipe for pound cake: 1 pound of eggs, 1 pound of butter, 1 pound of flour, and 1 pound of sugar. (That's why it's called "pound cake.") If you have 4 pounds of butter, how many pounds of sugar, flour, and eggs do you need? You would need 4 pounds each of sugar, flour, and eggs. Now suppose you have 1.00 g H 2. If the chemical reaction follows the balanced chemical equation \[\ce\nonumber \] Note how the unit molecules H 2 cancels algebraically, just as any unit does in a conversion like this. The conversion factor came directly from the coefficients in the balanced chemical equation. This is another reason why a properly balanced chemical equation is important. Solution We use the balanced chemical equation to construct a conversion factor between Fe 2O 3 and SO 3. The number of molecules of Fe 2O 3 goes on the bottom of our conversion factor so it cancels with our given amount, and the molecules of SO 3 go on the top. Thus, the appropriate conversion factor is \[\frac\nonumber \] We need 432 molecules of SO 3 to react with 144 molecules of Fe 2O 3. Exercise \(\PageIndex\nonumber \] Conversion factors like this can also be used in stoichiometry calculations.

[ "article:topic", "volume", "stoichiometry", "elements", "law of conservation of mass", "Molecular formula", "mass", "density", "stoichiometric factor", "chemical reaction", "combustion", "showtoc:no", "Products", "Reactants", "decomposition", "synthesis", "Acid-base", "Combination", "metron", "Balancing Reactions", "Balancing", "chemical symbols", "stoikhein", "Single Displacement", "Double Displacement", "Percent Mass", "Empirical Formulas", "license:ccbyncsa", "licenseversion:40" ] \( \newcommand\) • • • • • • • • • • • • • • • • Stoichiometry is a section of chemistry that involves using relationships between reactants and/or products in a chemical reaction to determine desired quantitative data. In Greek, stoikhein means element and metron means measure, so stoichiometry literally translated means the measure of elements. In order to use stoichiometry to run calculations about chemical reactions, it is important to first understand the relationships that exist between products and reactants and why they exist, which require understanding how to balance reactions. Balancing In chemistry, chemical reactions are frequently written as an equation, using chemical symbols. The reactants are displayed on the left side of the equation and the products are shown on the right, with the separation of either a single or double arrow that signifies the direction of the reaction. The significance of single and double arrow is important when discussing solubility constants, but we ...

In much the same way, a reactant in a chemical reaction can limit the amounts of products formed by the reaction. When this happens, we refer to the reactant as the limiting reactant (or limiting reagent). The amount of a product that is formed when the limiting reactant is fully consumed in a reaction is known as the theoretical yield. In the case of our hot dog example, we already determined the theoretical yield (four complete hot dogs) based on the number of hot dogs buns we were working with. To solve this problem, we first need to determine which reactant, A l \ce A l C l X 3 ​ . 2.80 g Al × 1 mol Al 26.98 g Al = 1.04 × 1 0 − 1 mol Al 4.15 g Cl 2 × 1 mol Cl 2 70.90 g Cl 2 = 5.85 × 1 0 − 2 mol Cl 2 \begin 2 . 8 0 g Al ​ 4 . 1 5 g Cl 2 ​ ​ ​ × 2 6 . 9 8 g Al ​ 1 mol Al ​ = 1 . 0 4 × 1 0 − 1 mol Al × 7 0 . 9 0 g Cl 2 ​ ​ 1 mol Cl 2 ​ ​ = 5 . 8 5 × 1 0 − 2 mol Cl 2 ​ ​ Now that we know the quantities of A l \ce C l X 2 ​ in moles, we can determine which reactant is limiting. As you'll see below, there are multiple ways to do so, each of which uses the concept of the mole ratio. All of the methods give the same answer, though, so you can choose whichever approach you prefer! Method 1: For the first method, we'll determine the limiting reactant by comparing the mole ratio between A l \ce C l X 2 ​ required by balanced equation is moles of Al moles of Cl 2 (required) = 2 3 = 0.6 6 ‾ \dfrac moles of Cl 2 ​ moles of Al ​ (required) = 3 2 ​ = 0 . 6 6 start fraction, start text...

In simple words, Stoichiometry is defined as the calculation of products and reactants in a given chemical reaction. It is principally concerned with numbers. The word “ stoichiometry” originated from the Greek word “stoikhein” which means element and the word “metron” means to measure. This term Stoichiometry was first proposed by a well-known German chemist Jeremias Richter. Stoichiometry is a significant concept in chemistry that helps us balanced calculate the quantities of reactants and products in a given chemical equation. For instance, oxygen and hydrogen react to form a substance called water in which one mole of oxygen reacts with two moles of hydrogen and hence forms two moles of water. In addition to this, stoichiometry can also be used to find quantities such as the amount of products that can be formed with a given quantity of reactants and percent yield. Stoichiometric coefficient or stoichiometric number is defined as the number of molecules that participate in the given chemical reaction. A balanced equation has an equal number of elements on both sides. The stoichiometric coefficient is mostly the number that is present before atoms, molecules, or ions. Stoichiometric coefficients can be in the form of fractions as well as whole numbers. In addition to that, the stoichiometric coefficients help to establish the mole ratio between reactants and the products of a given chemical equation. 1. Precipitation gravimetry involves isolation of ions in a given solu...

• Define stoichiometry. • Relate quantities in a balanced chemical reaction on a molecular basis. Consider a classic recipe for pound cake: 1 pound of eggs, 1 pound of butter, 1 pound of flour, and 1 pound of sugar. (That’s why it’s called “pound cake.”) If you have 4 pounds of butter, how many pounds of sugar, flour, and eggs do you need? You would need 4 pounds each of sugar, flour, and eggs. Now suppose you have 1.00 g H 2. If the chemical reaction follows the balanced chemical equation 2H 2(g) + O 2(g) → 2H 2O(ℓ), then what mass of oxygen do you need to make water? Curiously, this chemical reaction question is very similar to the pound cake question. Both of them involve relating a quantity of one substance to a quantity of another substance or substances. The relating of one chemical substance to another using a balanced chemical reaction is called stoichiometry. Using stoichiometry is a fundamental skill in chemistry; it greatly broadens your ability to predict what will occur and, more importantly, how much is produced. Let us consider a more complicated example. A recipe for pancakes calls for 2 cups (c) of pancake mix, 1 egg, and ½ c of milk. We can write this in the form of a chemical equation: 2 c mix + 1 egg + ½ c milk → 1 batch of pancakes If you have 9 c of pancake mix, how many eggs and how much milk do you need? It might take a little bit of work, but eventually you will find you need 4½ eggs and 2¼ c milk. How can we formalize this? We can make a conversio...