Stoichiometry Definition and 164 Threads

Stoichiometry is the calculation of reactants and products in chemical reactions in chemistry.
Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the total mass of the products, leading to the insight that the relations among quantities of reactants and products typically form a ratio of positive integers. This means that if the amounts of the separate reactants are known, then the amount of the product can be calculated. Conversely, if one reactant has a known quantity and the quantity of the products can be empirically determined, then the amount of the other reactants can also be calculated.
This is illustrated in the image here, where the balanced equation is:

Here, one molecule of methane reacts with two molecules of oxygen gas to yield one molecule of carbon dioxide and two molecules of water. This particular chemical equation is an example of complete combustion. Stoichiometry measures these quantitative relationships, and is used to determine the amount of products and reactants that are produced or needed in a given reaction. Describing the quantitative relationships among substances as they participate in chemical reactions is known as reaction stoichiometry. In the example above, reaction stoichiometry measures the relationship between the quantities of methane and oxygen that react to form carbon dioxide and water.
Because of the well known relationship of moles to atomic weights, the ratios that are arrived at by stoichiometry can be used to determine quantities by weight in a reaction described by a balanced equation. This is called composition stoichiometry.
Gas stoichiometry deals with reactions involving gases, where the gases are at a known temperature, pressure, and volume and can be assumed to be ideal gases. For gases, the volume ratio is ideally the same by the ideal gas law, but the mass ratio of a single reaction has to be calculated from the molecular masses of the reactants and products. In practice, due to the existence of isotopes, molar masses are used instead when calculating the mass ratio.

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  1. 9

    Stoichiometry, concentration of solutions: Ba(OH)2 and H3PO4

    Homework Statement What volume of 0.0521 M Ba(OH)2 is required to react completely with 24.50 mL of 0.141 M H3PO4? Phosphoric acid is a triprotic acid. Answer: volume of 0.0521 M Ba(OH)2 required = 99.5 mL 2. The attempt at a solution 1. I begin by balancing the equation: 3Ba(OH)2 +...
  2. Y

    Is This Stoichiometry Problem Truly Unsolvable?

    Homework Statement Toluene (C6H5CH3) is hydrogenated according to the two simultaneous chemical reactions C6H5CH3 + H2 → C6H6 + CH4 2C6H5CH3 + H2 → (C6H5)2 + 2CH4 Initially, the reactor contains 40% toluene and 60% H2 (% mole). At the end of the operation, the reactor contains 10% toluene and...
  3. W

    How Much Ice Remains When Water and Ice Reach Equilibrium in a Styrofoam Cup?

    A styrofoam cup contains 2.00x10^2 g of water at 21.0°C. A student adds 60.0g of ice at 0°C into this cup. Determine the mass of ice in the cup when the ice-water mixture reaches equilibrium. Qcold = -Qhot no idea where to start
  4. B

    [Chemistry] Chemical Reaction, limiting reactants and result stoichiometry

    Homework Statement 609.5 grams of vanadium (II) oxide, VO, and 832 grams of iron(III) oxide, Fe2O3, react according to the equation, which substance(s) and how many grams of each would be in the tube after the reaction completes? 3 points Homework Equations Equation: 2 VO + 3 Fe2O3 -> 6 FeO...
  5. A

    Weight % Nitrogen in 0.16 mol ATP: Calculate Now!

    C10H16N5O13P3 is the formula of ATP. What is the weight precentage of Nitrogen in 0.16 mol of ATP? Does it mean that in 0.16 mol of ATP I have 0.16 mol of N? or maybe of N5? I'm confused...
  6. jacksonpeeble

    Empirical Formula from Stoichiometry?

    Empirical Formula from Stoichiometry!? Homework Statement More than 1 billion pounds of adipic acid (MW 146.1 g/mol) is manufactured in the US each year. Most of it is used to make synthetic fabrics. Adipic acid contains only C, H, and O. Combustion of a 1.6380g sample of adipic acid gives...
  7. F

    Stoichiometry: Calculating Mass of HCl Neutralized by Milk of Magnesia

    1. Magnesium hydroxide, the active ingredient in milk of magnesia, neutralizes stomach acid, primarily HCl, according to the following reaction: Mg(OH)2(aq) + 2 HCl(aq) ---> 2 H2O(l) + MgCl2(aq) What mass of HCl, in grams, can be neutralized by a dose of milk of magnesia caontaining 3.26g...
  8. 5

    Stoichiometry hydrated NiSO4 question

    Homework Statement given that 40.14g sample of hydrated NiSO4 is reduced in mass to 22.14g upon heating. Show that the formula of the hydrate is NiSO4.7H20 Homework Equations n / M The Attempt at a Solution 22.14g/ 40.14g = 0.5516 (mol of NiSO4) 40.14g - 22.14 = (18 g H20 lost in heating)...
  9. M

    Calculating Oxygen Gas Released from Heating Calcium Chlorate

    Homework Statement How many millilitres of oxygen gas are released from heating 5.00 grams of calcium chlorate?Homework Equations Ca(ClO3)2→CaCl2+3O2 Ca(ClO3)2 =207.7g CaCl2=110.98g O2=22.4 g/L Mole ratio= 3mol O2/1mol Ca(Clo3)2 The Attempt at a Solution This is what I have but it is not...
  10. P

    Stoichiometry to find concentration and pH

    Homework Statement 15.1g of calcium hydroxide completely dissociates in distilled water forming 855ml of basic solution. a) Dissociation Equation b) Calculate the concentration of OH in the solution c)Calculate the pH of the above solution Homework Equations c=n/v pH=-log[H] The...
  11. T

    Stoichiometry with enzymes and temperature

    I'm currently doing an EEI with catalase and hydrogen peroxide. I'm just wondering about the effects of increasing the temperature of the catalase and h2o2. For example, if I get 50mL of oxygen produced when both are at 40°C and the reaction occurs for 8 seconds. If I decrease the temperature to...
  12. T

    Stoichiometry; calculation headaches

    Hi, I've been trying and trying but I can't seem to solve this. Hopefully, there's someone here kind enough to help me through :X 2.5g of impure CaCO3 was dissolved in 25.0cm^3 of 2.00 mol dm^-3 HCL in a 100cm^3 volumetric flask and made up to the mark with distilled water. This solution is...
  13. P

    Some Radiological Dating with Stoichiometry

    It's kind of baffling me when I'm encountering this question in this sub-chapter. It's just unusual. So I really need your help :D Homework Statement If a rock sample was found to contain 1.16 × 10-7 mol of argon-40, how much potassium-40 (t1/2 = 1.3 × 109 yr) would also have to be...
  14. MacLaddy

    Solving for NO2 in Nitric Acid Production Equation | Stoichiometry Assistance

    Homework Statement Nitric Acid is produced via the following equation: 3NO_2 + H_2O \rightarrow 2HNO_3 + NO How many grams of NO_2 are required to produce 7.50 grams of HNO_3? Homework Equations HNO_3 = 138 amu NO_2 = 126 amu The Attempt at a Solution I think I have a...
  15. T

    Introductory Stoichiometry Question

    A solution of KOH is prepared by dissolving 2.00g of KOH in water to a final volume of 250mL of solution. What volume of this solution will neutralize 20.0mL of 0.115 mol/L sulfuric acid? Homework Equations C=n/v C1V1=C2V2 n=m/M Attempt at solution First I balanced the equation...
  16. I

    Finding Mass through Stoichiometry of Ethanol in a chemical equation

    Homework Statement 1) What is the mass of 100% Ethanol? 2) How much ethanol would be expected from 18% glucose solution? 3) What else will be generated? How can we calculate this amount? Given: Fermentation Equation: C6H12O6(aq) + 2C2H5OH(aq) + 2CO2(g) + Heat...
  17. N

    How Much Ammonium Sulfate From 75kL Ammonia?

    ammonia reacts with sulfuric acid to form the important fertilizer, ammonium sulfate. what mass of ammonium sulfate can be produced from 75.0kL of ammonia at 10°C and 110 kPa? k so i actually have no idea of what to do, honestly we've never covered this in my class before and we have a test o...
  18. J

    Solution Stoichiometry Question?

    Solution Stoichiometry Question? Homework Statement When 300 mL of a 2 M solution of sodium hydroxide is mixed with 500 mL of 1M aluminum Nitrate a precipitate results. Determine the concentrations of all ions remaining in solution. I can do easier versions of these kinds of questions but...
  19. S

    Comparing Gas Stoichiometry Approaches: Which One is Correct?

    So iv solved all these problems, id just like someone to take a look at them and see which approach is right. The question is in the attachment. first approach is i use molar volume for SATP which is 24.76L and multiply 65L with it and i get 1609.4L then i use this in the universal gas...
  20. C

    What Volume of CO2 is Produced from H3PO4 and Na2CO3 Reaction?

    Homework Statement What volume of CO2 at 333 K and 90 kPa is produced when 0.4 L of 0.6 M solution of H3PO4 reacts with 36 g of Na2CO3? Homework Equations The Attempt at a Solution I calculated the moles for Na2CO3 and H3PO4 but I am lost
  21. B

    How to Solve the Second Problem in Solution Stoichiometry?

    Homework Statement The description of the problem is in the given link: http://s906.photobucket.com/albums/ac261/Bashyboy/?action=view&current=2011-10-11_21-13-53_241.jpg Homework Equations The Attempt at a Solution Well, I as was able to find the answer to the first problem...
  22. jacksonpeeble

    Introductory Solution Stoichiometry: Acids/Bases

    Homework Statement How many grams of solid calcium hydroxide are needed to react with 14.2 mL of a 1.62 M nitric acid solution? Assume that the volume remains constant when the calcium hydroxide is added. Ca(OH)2 + 2 HNO3 Ca(NO3)2 + 2 H2O Homework Equations Molarity=moles of...
  23. Q

    Stoichiometry - 0.7g of Na2CO3.xH2O were dissolved in water

    Homework Statement 0.7g of Na2CO3.xH2O were dissolved in water and the volume was made to 100 ml, 20 ml of this solution required 19.8 ml of N/10 HCl for complete neutralization. The value of x ? Homework Equations Na2CO3 + 2HCl = 2NaCl + H2O + CO2 The Attempt at a Solution I...
  24. Q

    How Do You Calculate the Normality of KMnO4 in This Stoichiometry Problem?

    Stoichiometry problem Homework Statement 1 g of H2O2 solution containing x % of H2O2 by weight required x ml of KMnO4 for complete oxidation in acid medium. What is the normality of KMnO4 solution? Homework Equations H2O2 + KMnO4 => 2KOH + 2MnO2 + 2O2 The Attempt at a Solution...
  25. Q

    Solving Potassium Dichromate Homework Problem

    Homework Statement How many grams of potassium di chromate (K2Cr2O7) are present in 1 lit of its N/10 solution in acid medium?Homework Equations gram eq = NV = g/E = xg/M The Attempt at a Solution gram eq = NV = 0.1 * 1 = 0.1 g = gram eq * mol wt / valence factor (The valence factor I have...
  26. P

    How Do Stoichiometry Calculations Reveal Chemical Quantities and Composition?

    1.nitric acid reacts with potassium carbonate according to the following reaction 2(HNO3) + k2CO3 ----> 2(KNO3) + H2O + CO2 if nitric acid is reacted with 50.0 g of potassium carbonate, find the mass of water produced 2. manganese is added to steel to increase strength and resistance to...
  27. T

    Stoichiometry to find the concentration of O2?

    2 Mn2+ + O2 + 4 OH- -> 2 MnO2 + 2 H2O ***** Use the stoichiometry of the chemical reaction to calculate the concentration (mg/L) of O2(aq) and concentration of O2 (aq) (Molarity). DI Water (22 degrees C) Initial Buret Reading: 20.0ml Final Buret Reading: 28.7 ml Volume Na2S2O8 to reach the...
  28. N

    How to Convert Natural Gas into Butadiene with Catalytic Reactions?

    Homework Statement A neutral gas sample contains 84% ( by volume ) of CH4 , 10 % of C2H6 , 3 % of C3H8 and 3% of N2 . If a series of catalytic reacns cud be used for converting all the C atoms of the gas into butadiene , C4H6 , with 100% efficiency , how much butadiene cud be prepared frm 100...
  29. O

    Taking Engineering Classes. eg. CBEE 211 (material balances and stoichiometry)

    okay, Through lurking, I've gotten a better understanding of how to tackle math, physics, and chemistry classes. My question is then how would you tackle Engineering classes? namely my CBEE 211 class. I know the key is practice, but this class takes a ridiculous amount of time. It's nice to...
  30. N

    Calculating Percent Yield for a Chemical Reaction

    Homework Statement 1. If we mix 25 grams of sodium bromide with a large amount of potassium chloride, what will our theoretical yield of sodium chloride be? 2. If our actual yield from this reaction was 18 grams of sodium chloride, what would our percent yield for this reaction be...
  31. A

    How Much Propylmagnesium Bromide is Needed for This Grignard Reaction?

    I'm in organic chemistry 1. We haven't gone over the Grignard reaction in class, but there was a stoichiometry problem assigned about one and I don't know how to get it started. Homework Statement The following Grignard reaction is performed. Calculate how much of a 0.50M solution...
  32. B

    How Do You Calculate the Mass of CO2 in a Baking Soda and Vinegar Reaction?

    the question is: Sodium Hydrogen carbonate (baking soda) is reacted with excess acetic acid (vinegar) with a concentration of 0.500mol/L in an Erlenmeyer flsk. The proucts are sodium acetate, water and carbon dioxide gas. The gas produced is collected in a balloon attached to the flask, tied...
  33. K

    Stoichiometry of Precipitation Reactions

    Homework Statement What mass of iron(III) chlorate is needed to precipitate all the chromate ions from 234 mL of a 0.100 M lithium chromate solution. Homework Equations The Attempt at a Solution we just started precipitates and my teacher didnt explain the procedure very well...
  34. A

    Reaction of gases/ gas stoichiometry

    Homework Statement The reaction of 50 mL of H2 gas and 50 mL of N2 gas via the equation: 3H2 + N2 ---> 2NH3 will produce how many mL of product? A reaction of 25 mL of Hydrogen gas and 75 mL of Nitrogen gas? Assume that temperature and pressure are constant. Homework Equations...
  35. G

    How Deep Would the Water Ice Layer Be on the Moon?

    Homework Statement During the Apollo missions, each lunar module decelerated toward the surface of the moon by the oxidation of "Aerozine-50" fuel. Aerozine-50 is a blend of hydrazine, N2H4, and dimethylhydrazine, CH3()2N2H2, 50% by mass in each component (known to infinite precision)...
  36. M

    What is the Molar Ratio for Dissolving Aluminum with Sulfuric Acid?

    Homework Statement sulfuric acid dissolves aluminum metal according to 2 Al(s) + 3 H2SO4 ---- Al2(SO4)3 (aq) + 3 H2 find minimum mass of H2SO4 in g if you wanted to dissolved aluminum block with mass of 15.2 g Homework Equations see above The Attempt at a Solution 15.2 g Al x...
  37. R

    Stoichiometry Help: Calculating NaOH for CO2 Removal in a Spacecraft

    As early as the 1938, the use of NAOH was suggested as a means of removing CO2 from the cabin of a spacecraft according to the reaction: 2NaOH+CO2--->Na2CO3+H2O If the average human body discharges 592g of CO2 per day, how much NaOH is needed each day for each person in the spacecraft ?
  38. A

    How much work is done during the combustion of 1.0 mol of octane at 1.0 atm?

    Homework Statement The change in internal energy for the combustion of 1.0 mol of octane at a pressure of 1.0 atm is 5084.5 Kj. If the change in enthalpy is 5074.2 Kj, how much work is done during the combustion? Find work in Kj. Homework Equations \DeltaE=\DeltaH + (-P\DeltaV)...
  39. R

    Need help on two questions (electron configuration and stoichiometry

    A compound is analyzed and it contains H,N,O and C. The original sample is 1.3957 grams. The sample is burned in excess oxygen to form 2.24 grams of CO2. 0.04 grams H is evaluated in the original sample. a. What are the grams of oxygen in the original sample? b. The original compound contains...
  40. D

    Stoichiometry: confused about the question

    Homework Statement a 4.22g mixture of CaCl2 and NaCl was dissolved, and then treated to precipitate all of the Ca as CaCO3, which was then heated to drive off CO2, leaving a sample of pure CaO which was found to weigh 0.969g. What percentage of the original mixture was CaCl[/SUB]2[/SUB]? I...
  41. D

    How Do You Calculate the Molecular Formula of a Gas Compound in Stoichiometry?

    Homework Statement a sample of gas compound is made up only of B and H weighing 0.596g occupies 484 mL at STP. *then burned in excess O2, it yields 1.17g of H2O and all of the boron is converted to B2O3 what is a) its empirical formula? b) its molecular weight? c) its molecular formula? d)...
  42. K

    What Volume of Copper Sulfate Solution is Needed for 1.110g of Iron?

    URGENT Chemistry Stoichiometry Help :S Homework Statement Suppose that you use 1.110g of iron in this experiment. What is the minimum volume of 1.0M copper sulfate solution that you should add? Homework Equations Fe(s) + Cu2+(aq) --> Fe2+(aq) + Cu(s) (1) 2Fe(s) + Cu2+(aq)...
  43. W

    What is the difference between O and O2 in stoichiometry calculations?

    Homework Statement Hi, 4Al + 3O2 --->2Al2O3 Given 20g of Al and 15g Oxygen which is limiting factor? Homework Equations My question is the difference between O2 and Oxygen. Do I start with a mole of O or O2 in my calcs? Since the question is framed "15g of oxygen" (verbatim from a...
  44. H

    Losing my mind over Stoichiometry

    Alright, here we go... First off I just want to warn you all that I'm very bad @ math, so this might take a little explanation. I'm currently in a Gen Chem class and can't get a grasp on this Stoichiometry stuff. One of the ?'s I'm looking at is this: 1.2g AgNO3 + 0.5g Cu + 100ml H2O --->...
  45. N

    Cell Stoichiometry: Mass of Na Deposited in 2h

    Homework Statement Determine the mass of sodium deposited at the cathode of a molten NaCl(l) electrolytic cell if 10.0 A flow through the cell for 2.00h. Homework Equations The Attempt at a Solution For the mole ratio, Na+ +e --> Na 2Cl- --> Cl2 + 2e Should I balance the...
  46. D

    Which Professions Utilize Stoichiometry in Their Daily Work?

    Hi guys, I was just wondering, what professions include Stoichiometry. I learned it in class, but found it pretty useless in real life. I have been told that historians require the use of Stoichiometry, but I couldn't find out how. Can someone explain how Historians can use this concept...
  47. B

    Gas Stoichiometry: Calculate Volume of Wet Acetylene

    Homework Statement Calcium carbide reacts with water to produce acetylene gas: CaC2 (s) + 2H2O (l) >> Ca(OH)2 (aq) + C2H2 (g). What volume of wet acetylene is collected at 25C and 715 torr when 5.20g CaC2 is reacted with an excess of water? (Vapor pressure of water at 25C = 23.8 torr)...
  48. S

    Solve Redox Stoichiometry Homework: AgCl + ZnI2

    Homework Statement a 0.245 mol/L silver chloride solution is mixed with 50.0 mL of 0.200 mol/L zinc iodide solution. what volume of silver chloride solution is needed for a complete reaction? (answer is 81.6mL) Homework Equations The Attempt at a Solution Ag+ is the strongest OA, I- is the...
  49. T

    Electrolytic reduction of iron ore - Stoichiometry

    Homework Statement Calculate the maximum mass of aluminum that can be made from 408 tonnes of alumina, assuming that aluminum is produced by electrolysis. Homework Equations At the cathode: Al^{3+} (l) + 3e^{-} \Rightarrow Al (l). At the anode: O^{2-} (l) \Rightarrow O_2 (g) + 4e^{-}. Is...
  50. T

    How Do You Solve These Chemistry Stoichiometry Problems?

    1. Graphite is a crystalline form of carbon used in "lead" pencils. How many moles of carbon are in 315mg of graphite? 2. 315mg = .315g 0.315 g C (1 mol C / !2 g C) 3. 0.026 mol C 2.1 Manganese is a transition element essential for the growth of bones. What is the mass in grams of 3.22 x 10^20...
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