Stoichiometry Calculations Essay

Stoichiometry Calculations EssayRegina MarinChapter 12Stoichiometry division 1 WHAT IS STOICHIOMETRY?Mole-Mass Relationships in chemic reactionsThe balance equatings is the main basis of stoichiometry, and that is the first thing to do when you want to streak a chemical process. The information provided by the chemical equation is interpreted according to the needs. And the inguen is associated with the jettyecular weight, the zep proportionalitys of an equation can be associated with authoritative of the substances involved by the mol mass. The transformations that occur in a chemical reaction is governed by the law of conservation of mass Atoms are neither created nor destroy during a chemical reaction.Lets try to interpret an equation in terms of moles, particles, and mass.Remeber 2 important facts The coefficient indicates the amount of moleculesThe coefficient also indicates the amount of moles consequently lets get the mass of the reactants and the products by usin g conversion.Moles reactant/product * grams reactant/product / 1 mole reactant/product = grams reactantMole RatiosWe know that there is a direct descent between mole and molecule. This relationship is Avogadros number. A mole always contains Avogadros number of molecules. Thus the relationships between molecules given by the stoichiometric coefficients are also legitimate for moles. When a chemical reaction in the molar ratios of reactants and products are given, if you can have fractional stoichiometric coefficients, since the amounts of molecules involved are very high, and we can lecturing about half mole of molecules or of a third mole of molecules.Stoichiometric coefficients indicate the proportion that the moles of reactants and products involved in a chemical reaction.SECTION 2 STOICHIOMETRIC CALCULATIONSStoichiometric mole-to-mole ConversionIn this type of reaction the starting material is expressed in moles, and the desired substance are quest in moles. In stoichiomet ric calculations results are reported be rounded to two quantitatives. Similarly, the atomic masses of elements should be used rounded to two decimals.Recalling move to two decimal places, we use as a basis the third decimal. If this is greater than or equal to 5, increase one unit to two decimal places if less than or equal to 4 the second decimal lacifra be retained.So lets see the steps to make a mole to mole conversion misuse 1 Balancing the equationReviewing the equation we make sure that is really well balanced. We can represent the balanced equation in the data and the unknown exercise.STEP 2 IdentifyWe need to identify the substance that we are looking for and the one that we are starting of.STEP 3 Apply the mole ratio.The moles of desired substance and starting the get from the balanced equation.Stoichiometric mole-to-mas ConversionTo get wind the mass of a product, is enough to cover the moles of the product by its molecular weight in g / mol.Stoichiometric mass-to-mas s conversionMolar factor method is based on the ratio of the number of moles between two substances participating in a chemical reaction.Step 1 Balance the equationStep 2 Determine the molar factor, which is equal to the number of moles searched on the number of moles known.Step 3 Find the moles of O2 from O2 500gStep 4 Find the moles of SO3 from the O2Step 5 We find the grams of SO3 after the SO3 mol 31.25SECTION 3 LIMITING REACTANTSWhy do Reactions Stop?When adjusted equation, the coefficients represent the number of atoms of each element in the reactants and the products. Also represent the number of molecules and moles of reactants and products. When an equation is set, the stoichiometry is used to find the moles of a product obtained from a known number of moles of a reagent. The mole ratio between reactant and product is obtained from the fitted equation. Sometimes mistakenly believes that the reactions are always used the exact amounts of reagents. However, in normal practic e it is usually an lavishness of one or more reactants are used, to ensure that the widest affirmable to react the less abundant reactive.Limiting ReactantsWhen a reaction is stopped because just one of the reactants, that reactant is called the bound reactant. One reactant that has been only consumed in a chemical reaction is known by the name of limiting reagent as it determines or limits the amount of product formed.Limiting reagent is one that is in default based on the balanced chemical equation2H2 + O2 2H2OIn the equation above, What is the limiting reactant if we have 10 molecules of atomic number 1 and 10 oxygen molecules?Need 2 molecules per molecule of H2 O2 barely we only have 10 molecules of H2 and 10 molecules of O2.The required ratio is 2 1But we have the proportion is 1 1It is clear that the excess reagent is the limiting reactant O2 and H2 isHow to work with molecules is the same as working with moles.If we now put 15 moles of H2 with 5 moles of O2 so as the s toichiometry of the reaction is such that 1 mol of O2 reacts with 2 moles of H2, then the number of moles of O2 needed to react with all the H2 is 7, 5, and the number of moles of H2 required to react with all the O2 is 10.That is, that after all the oxygen has been consumed, 5 moles of hydrogen left over. The O2 is the limiting reactantOne way to work on the problem of what is the limiting reagent isCalculate the amount of product to be formed for each of the quantities to the reaction reagent.The limiting reactant is one that produces the least amount of product.Excess ReactantThe reactant is completely consumed is called the limiting reagent because it determines the amount of product that can be produced in the reaction. When the limiting reactant is consumed, the reaction is stopped.The reactant reacts not completely, solely plenty, is called the excess reagent. If we have a certain amount two elements or compounds to produce a chemical reaction, we can know in advance what p ull up stakes be the limiting reagent and excess reagent which, making some calculations based on the balanced chemical equation.SECTION 4 PERCENT YIELDHow much product?When the stoichiometric calculations for finding as a substance produced in a chemical reaction is made, it is expected that the amount produced of the substance will always be less than the amount of the substance to be obtained , this happens because not everything reacts completely converted to product , ie not all that does react 100% . Because of this, in stoichiometry judgment kick in percentage is included , the percent yield is a chemical reaction is the ratio between the actual performance and theoretical performance, the ratio of grams that in truth occur in the reaction and grams that would be obtained if all you react is transformed into product.If a problem involving a chemical reaction term refers to the theoretical yield of a reaction means that we take as if everything becomes reactive product , ot herwise we would be talking about an actual performance. The equation used to solve problems that involve the performance of a chemical reaction is as follows . % Yield = (actual yield ( g ) ) / (theoretical yield ( g ) ) 100 % If a problem of chemical reaction we give grams that actually produce a substance by reacting certain amount of reactant either molar or mass , it can find the percentage yield of the reaction using this equation, because they would not be given the actual performance and theoretical performance assuming that the substance would find completely react .