Explore BrainMass

Reaction Stoichiometry

Reaction Stoichiometry refers to the examination of the relative abundances of reactants and products in a chemical reaction within a defined system. In order to use reaction stoichiometry to calculate desired quantitative data, it is important to first understand the relationships between the reactants and the products. This requires the process of balancing reactions, which is usually the most important step when doing stoichiometric calculations.

To balance an equation, it is necessary that there are the same number of atoms in the reactants as there are in the products. One can do this by raising the coefficients of individual reactants or products.

For example, the combustion of methane involves reacting methane (CH4) and oxygen (O2) to form carbon dioxide (CO2) and water (H2O). The unbalanced chemical equation can be written as:

CH4(g) + O2(g) --> CO2(g) + H2O(l)

It can be seen that the number of atoms on each side are unbalanced; and so raising the coefficients of O2 and H2O to 2 will balance the equation for the combustion reaction:

CH4(g) + 2O2(g) --> CO2(g) + 2H2O(g)

Thus, from these stoichiometric coefficients, it can be seen that 1 mole of methane reacts with 2 moles of molecular oxygen to form 1 mole of carbon dioxide and 2 moles of water. Using these relative ratios, one can hypothetically say that 0.1 moles of methane requires 0.2 moles of oxygen or 0.6 moles of methane requires 1.2 moles of oxygen. Therefore, understanding the relationship between reactants and products is absolutely fundamental to run stoichiometric calculations on chemical reactions.

Balancing and stoichiometry questions

1. For the equation, Al + O^2 Al^2O^3 answer the following questions: a. Balance the above equation. b. If 10.0 g of Al are used, how many g of oxygen are needed and how many g of product are produced? ?c. If you had 20 moles of Al, how many moles of oxygen would be needed and how many moles of product would be produced?

Magnesium Stoichiometry

Magnesium can be used as a "getter" in evacuated enclosures, to react with the last traces of oxygen. (The magnesium is usually heated by passing an electric current through a wire or ribbon of the metal.) If an enclosure of 0.384 L has a partial pressure of O2 of 3.6×10−6 torr at 28 C degrees, what mass of magnesium

Energy, q, w, Enthalpy, and Stoichiometry II and Specific Heat

Problem 1 - Energy, q, w, Enthalpy, and Stoichiometry Consider the following reaction: 2Mg(s)+O2(g)>>2MgO(s)ΔH = -1204kJ 1) Is this reaction exothermic or endothermic? 2) Calculate the amount of heat transferred when 2.1 g of Mg(s) reacts at constant pressure. Express your answer using two significant figures.

Chemistry Stoichiometry - Limiting Reactants

The fizz produced when an Alka-Seltzer® tablet is dissolved in water is due to the reaction between sodium bicarbonate (NaHCO3) and citric acid (H3C6H5O7): 3NaHCO3(aq)+H3C6H5O7(aq)>>3CO2(g)+3H2O(l)+Na3C6H5O7(aq) In a certain experiment 1.05g of sodium bicarbonate and 1.05g of citric acid are allowed to react. - Which is

Theoretical and percentage yield

When benzene (C6H6) reacts with bromine (Br2), bromobenzene (C6H5Br) is obtained: C6H6+Br2>>C6H6Br+HBr - what is the theoretical yield of bromobenzene in this reaction when 27.0 g of benzene reacts with 58.5 g of bromine? - if the actual yeild of bromobenzene was 49.9g, what was the percentage yield?

Stoichiometry: How Many Grams of Zinc Oxide Are Formed

When zinc sulfide is heated in air, zinc oxide and sulfur dioxide forms: 2ZnS(s) + 3O2(g) = 2ZnO(s) + 2SO2(g) How many grams of zinc oxide is formed when 100 grams of zinc sulfide is burned? Assume that the zinc sulfide is the limiting reactant. The answer is one of the following: a. 8.5 grams ZnO b. 23.5 grams ZnO c. 4

Stoichiometry in Reactions of Aluminum and Sodium Hydroxide

6) Explain why the reaction of 31.1636 g of aluminum metal (atomic mass 26.9815 g/mol) with 110.00 g of sodium iodate (molar mass 197.89 g/mol) in the presence of nitric acid produces the equivalence of only 25.00 g of aluminum ions; whereas,reaction with 120.00 g of sodium iodate produces the equivalence of 31.1636 g of aluminu

Titration problems

In the reaction CaCO3 + 2HNO3 → Ca(NO3)2 + CO2 + H2O, how many milliliters of 0.1015 M HNO3 are required to react with 0.9857 grams of CaCO3? Find the fraction of association of a 0.120 molar solution of hydrogen cyanate. Ka for hydrogen cyanate = 3.30×10-4. A sample containing 0.2784 grams of sodium chloride

Chemical Engineering: Stoichiometry and Mass Balance

Please see the attached file for the fully formatted problems. Just do A3 and A4, please. A3. Solid calcium fluoride (CaF2) reacts with sulphuric acid to form solid calcium sulphate (CaSO4) and gaseous hydrogen fluoride (HF). The HF is then dissolved in water to form hydrofluoric acid. A source of calcium fluoride is fluorite

Stoichiometry of calcium chloride and sodium phosphate

Calcium chloride and sodium phosphate react to form solid calcium phosphate in the following reaction: 3CaCl2 + 2Na3PO4 = Ca3(PO4)2 + 6NaCl What mass of sodium phosphate is required to react completely with 9.75 grams of calcium chloride?

Calculating Moles and Mass: Example Problem

Several brands of antacids use Al(OH)3 to react with stomach acid, which contains primarily HCl: alpha Al(OH)3(s) + beta HCl(aq) = gamma AlCl3(aq) + delta H2O(l) Balance the equation. Calculate the number of grams of HCL that can react with 0.560g of Al(OH)3. Calculate the number of grams of AlCl3 formed when 0.560

glucose produced by small patch of trees

Burning of fossil fuel (equation a), gasoline, produces carbon dioxide CO2;, one of the global warming contributors. But carbon dioxide plays an important role in photosynthesis which reacts with water in the presence of sunlight and produces glucose and oxygen gas according to the equation below (equation b). Excessive loggin

Stoichiometry of an Acid-Base Reaction

Procedures: 1. Take a beaker from the Glassware shelf and place it on the workbench. ***mass of empty beaker is 47.420g*** 2. Take a balance from the Tools shelf and drop it directly onto the beaker. Record the mass of the empty beaker. 3. 0.5g of Na₂CO₃ to the beaker. Record the mass of the beaker plus Na₂CO₃. R

12 Problems: Stoichiometry, Yield and Substance Remaining

Calculate how many moles of each product would be complete conversion of 1.25 mol of the reactant indicated in boldface, what is the mole ratio used. C2H3OH (I) + 302(g)  2CO2(g) + 3H2O(g) N2(g) + O2(g)  2NO(g) 2NaClO2(s) + Cl2(g)  2ClO2(g) + 2NaCl(s) 3H2(g) + N2(g)  2NH3(g) Calculate the m

Balanced equations for the various steps in synthesizing lidocaine

The reduction of 1,3-dimethyl-2-nitrobenzene to 2,6-dimethylaniline involves two steps. I am having difficulty balancing the equations, and I have no idea of the mechanism involved. Ar(CH3)2 + SnCl2.2H2O +HCl --> Ar(CH3)2(+)Cl(-) + SnCl4 (step 1) Ar(CH3)2(+)Cl(-) + KOH --> Ar(CH3)2NH2 (step 2) I could also use help with the

Ascorbic Acid: Acidity, Titration, and Ionic Concentrations

1. Calculate the molarity of the ascorbic acid solution: (a) Mass of ascorbic acid used: 0.1 (b) Moles of ascorbic acid (MW=176.1 g/mol): not sure (0.000568g/moL) (c) Volume of solution (mL): 100.01mL (d) Ascorbic acid concentration (mol/L): 2. For each titration, record and calculate the following:

Heat in Reactions

[show your work and note what formulas you used] A mercury mirror forms inside a test tube by the thermal decomposition of mercury(II) oxide. 2 HgO(s) 2 Hg(l) + O2(g) Hrxn = 181.6 kJ 1. How much heat is needed to decompose 505 g of the oxide? 2. If 270. kJ of heat is absorbed, how many grams of mercury form?

Balance Equations and Mass Percent

Problem: Iodine is present in Chilean saltpeter as iodate anion (IO3-). The amount of iodate anion in a particular sample may be determined by dissolving the sample and then reacting the IO3-(aq) with excess aqueous sodium bisulfite (NaHSO3(aq)) via: 2 IO3-(aq) + NaHSO3 (aq) -----> I2(aq) + Na+(aq) + 5SO4-2(aq) + H+(aq) + H2O(l)

Mole Consumption

In equation: N2+3H2 > 2NH3, how many moles of hydrogen are required to produce 556g ammonia?

Stoichiometry and Multiplying Electrons

Complete and balance the following reaction: As(s)+ClO3^-(aq) (right arrow) H3AsO3(aq)+HCLO (aq) I have the following options: -split into 1/2 reactions -balance all but H and O -balance O by adding H20 -balance H+ by adding protons -balance charge by adding electrons I am stuck, after adding equations to get electro

Stoichiometry/balancing redox reactions

I need help on how to balance redox reactions in a systematic way. I already have the answers, I need to know step-by-step how to get there...thanks! Example: cCmplete and balance the following reaction: H2O2+Cl2O7 (right arrow) Clo2^- +O2 (which occurs in basic solution) Also - how do you tell what was oxidized and what wa

Stoichiometry Reaction Maximum Amount

I have a couple of problems that I am struggling with. For the reaction 2NO+O2->2 NO2 what is the maximum amount (in g's) of NO2 which could be formed from 6.49g of NO and 18.8 g or O2? For the reaction 2CO+O2->2CO2 what is the maximum amount (in units of mol.) of CO2 which could be formed from 16.02g of CO and 1.16g of

Using Stoichiometry Ratios

Reaction: 5C + 2SO2 -> CS2 + 4CO Questions: 1) How many moles of CS2 are there for when 2.7 moles of C reacts? 2) How many moles of carbon are needed to react with 5.44 moles of SO2? 3) How many moles of carbon monoxide form at the same time that .246 moles of CS2 forms? 4) How many moles of SO2 are required to make 118

Stoichiometry Question

Stoichiometry Question NASAs long term plans for sending astronauts to Mars involves an ISRU strategy. ISRU is in-situ resource utilization and means that to the extent possible, chemical resources already on Mars will be utilized. The Martian atmosphere contains about 95.3% carbon dioxide. According to one NASA plan, hydroge