What is Stoichiometry: Definition and 164 Discussions
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.
Homework Statement
A student has 4.00g of Copper Chloride (CuCl2) and 25.0 g of Aluminum (Al). Calculate the mass of each reactant and product present at the end of the reaction. Show your calculations.
Homework Equations
3 CuCl2 + 2Al \rightarrow 3Cu + 2AlCl3
The Attempt at a...
1. Chromium(III) Oxide reacts with Hydrogen Sulfide(H2S) gas to form Chromium Sulfide and water.
CR2O3(s) + H2S(g) = Cr2S3(s) + H2O (l)
to produce 439g of Cr2S3.
a. How many moles of Cr2O3 are required?
b. How many grams of CR2O3 are required?
2. Not sure how to set this up...
Homework Statement
H2SO4 + Na2CO3 g Na2SO4 + H2O + CO2
Calculate the molarity of the H2SO4 solution if it takes 40.0 mL of H2SO4 to neutralize 46.7 mL of a 0.364 M Na2CO3 solution.
The Attempt at a Solution
The equation is balanced. My plan was...
Homework Statement
Calculate the volume of 0.108 M NaOH solution required to react completely with 145 mL of phosphoric acid solution that is 1.15x10^-2 M.
Homework Equations
n=MV
The Attempt at a Solution
NaOH \rightarrow Na^{+}+OH^{-}
H_{3}PO_{4} \rightarrow 3H^{+} + PO_{4}^{-}...
stoichiometry. Please help . Thanks!
1. how many grams of Lead(II) Sulfide will result from the combination of 146.0 grams of ammonium sulfide and excess Lead (II) Nitrate
Homework Equations
3. ooohhhkkaayyy .
I cannot even balance the equationn... sooo
this is what i have...
This is what I was given:
Answer all of the questions concerning the combustion of table sugar,
C_1_2H_2_2O_1_1(s) + 12O_2 (g)\rightarrow 11H_2O(g) + 12CO_2(g)
a. If (weird triangle shape thing(what is this thing anyways?))H for this reaction is -5645 kj/mol, how much heat is...
Stoichiometry... Did I work this problem correctly?
1. We dissolve 3.778 grams of a sample that contains some sodium oxalate, Na2C2O4, in water and acidify the solution with excess sulfuric acid. The sample requires 18.74 mL of 0.08395 M KMnO4, potassium permanganate, for complete reaction...
Chemistry Homework-- Stoichiometry: Volume and Particle Calculations
This is only to check my work, and I may be updating this post with more problems. There are ten questions total, and this is NOT graded. Therefore, the help I receive goes toward my understanding, not my score.
Homework...
Salutations,
The answer obtained below doesn't match any of the options given in the enunciation.
Thank you in advance.
Homework Statement
A sample of dolomitic limestone, containing 60% of calcium carbonate and 21% of magnesium carbonate, goes through decomposition when heated, according to...
Thank you in advance for the correction of the resolution.
Homework Statement
By reacting 225 g of hydrochloric acid with 300 g of calcium carbonate with 80% of purity, 34 L (litres) of gas were obtained, measured at 37oC and a pression of 0.82 atm. What is the yield of this reaction and what...
Thank you in advance.
Homework Statement
Nitrogen gas can be obtained from the reaction between sodium azide and iron oxide.
6NaN_3_{(s)}+Fe_2O_3_{(s)} \rightarrow 3Na_2O_{(s)}+2Fe_{(s)}+9N_2_{(g)}
a) What is the yield of this reaction, knowing that, from 390 g of azide and 400 g of...
Calculate the volume of 3.0 mol HCl required to react completely with 10.0g of Na2CO3.
Im confused about the "volume". What do they mean ?
Do I have to find the mass of HCl then convert it into a volume?
Homework Statement
0.800 g of silver nitrate and 0.473 g of potassium bromate are added to 238 mL water. Solid silver bromate is formed, dried, and weighed. What is the mass, in g, of the precipitated silver bromate? (Be careful to enter the correct number of significant figures. Do not...
Homework Statement
mixture of CaCO3 and CaO m=0.656 g, heated to produce CO2. After heating, only CaO solid remains and it weighs 0.485 g.
Assuming all the CaCO3 decomposed to CaO and CO2, calculate the mass percent of CaCO3 in the original mixture.
Homework Equations
The...
Homework Statement
I have to find the mass of HCl (in grams) that is produced given the below reaction yields 18.7g of H3PO4.
Homework Equations
PCl5 + 4H20 -> H3PO4 + 5HCl
The Attempt at a Solution
I calculated the # of mols for H3PO4.
I want to confirm if this mol value...
In a question I was asked to "Calculate the empirical formula and the molecular formula." The following question references "the above compound" in the statement. Which one should I be using in the calculations of the next question, the empirical or molecular formula?
Homework Statement
I don't understand this problem, i think he wants me to find the limeted reaction. If you could explain as good as possible. Thanks :smile:Homework Equations
Al(OH)3(s) + H2SO4(l) → Al2(SO4)3(aq) + H2O(l)
If 1.28 g of aluminum hydroxide reacts with 3.73 g of sulfuric acid...
Homework Statement
This problem is giving me trouble on many levels.
Gold III hydroxide is used for electroplating gold onto other metals. It can be made from the reaction of KAuCl4 (aq) with sodium carbonate and water.
a. Write a balanced equation for this reaction.
b. To prepare a...
Homework Statement
"How many grams of hydrogen are necessary to react completely with 50.0g of nitrogen in the below reaction?"
Homework Equations
N2+3H3 ---> 2NH3The Attempt at a Solution
16.1g H?
[SOLVED] Stoichiometry Solving for unknow
Ok so this should be a simple, I know the answer from the key but need to know how to get to that answer.
Q: When 1.187g of a metallic oxide is reduced with excess hydrogen, 1.054 grams of the metal is produced. What is the metallic oxide?
A)...
6.0 moles of N2 that's are mixed with 12.0 moles of H2 according to the following equation:
The equation is already balanced:
N2(g)+ 3H2(g) yields 2NH3 (g)
The questions asks for what is the chemical in excess? is it H2 or N2
I solved the problem but i want to make sure if it is right...
Homework Statement
Saponification is the process by which soap is made. A triglyceride is reacted with NaOH to produce a carboxylic acid salt (the soap) and glycerol
Lard, mostly made of trioleic acid (TOA) is used with Lye (NaOH) in homemade variations
molar mass of TOA is 848g/mol
molar...
Homework Statement
5.00g alloy of Magnesium and Aluminum is treated with excess HCl, forming MgCl2 and AlCl3 and 6.65L of H2 at 25 degrees celcius and 99.2kPa. What is the mass percent of Mg in the alloy?
Homework Equations
PV = nRT
The Attempt at a Solution
Using PV = nRT...
1. Oxalic acid, H2C2O4, reacts with dichromate ion, in acidic solution to produce carbon dioxide and chromium(III) ion.
If exactly 50.0 mL of an oxalic acid solution is required to react completely with 25.0 mL of a 0.0100 M dichromate solution, what is the molarity of the oxalic acid...
Hey Guys, I'm having a little trouble with this problem:
A mixture of Mg(NO3)2 and its hydrate Mg(NO3)2*2H2O has a mass of 1.7242 g. After heating to drive off all the water, the mass is only 1.5447 g. What is the percentage of Mg(NO3)2*H2O in the original mixture? Report your answer to 4...
The Title should actually be "Gravimetric Analysis"
srry about that but i can't change it now :(
1.
A 6.34-g geological sample, containing the mineral Boulangerite (Pb5Sb4S11) as the only lead-bearing compound, is subjected to chemical treatment in which the lead is quantitatively...
Homework Statement
Have to answer all of the following...
A. By titration, 15.0mL of 0.1008M Sodium hydroxide is needed to neutralize a 0.2053g sample of an organic acid. What is the molar mass of the acid if it is monoprotic?
B.An elemental analysis of the acid indicates that it is composed...
I'm trying to figure out where the often cited 14.7:1 stoich a/f ratio for gasoline comes from. I've always thought it was calculated from a primary reference fuel containing some mixture of iso-octane and n-heptane. But I've done the calculations for those hydrocarbons and my numbers don't...
I'm looking for some help with the stoichiometry of gasoline. 14.7:1 is commonly cited as the stoich ratio for gasoline and air. I believe this ratio is calculated using a primary reference fuel consisting of a mixture of n-heptane and iso-octane. Precisely what mixture is unknown to me...
Homework Statement
A sealed 1.00 L vessel contains 0.3475 g of argon gas and 6.766 g of an unknown gas at 350 K. If the total pressure of the gas mixture is 2.56 atm, and the unknown gas has an empirical formula of CH2, what is the molecular formula of the unknown gas?
Homework Equations
I...
Data Table
.........NaHC O3...CaCO3
1. Mass of micro plate.....2.05g....2.05g
2. Mass of micro plate +salt...3.05g...3.05g
3. Mass of Salt .....1g.....1g
4. Moles of salt.....1/84 mol...1/100 mol
5. Mass of unreacted setup...20.66g....17.9g
6. Mass of reacted setup.....20.58g...17.85g
7...
Data Table
.........NaHCO3...CaCO3
1. Mass of micro plate.....2.05g....2.05g
2. Mass of micro plate +salt...3.05g...3.05g
3. Mass of Salt .....1g.....1g
4. Moles of salt.....1/84 mol...1/100 mol
5. Mass of unreacted setup...20.66g....17.9g
6. Mass of reacted setup.....20.58g...17.85g
7...
is anyone familiar with the BCA (Before, Change, After) table?
if so i need someone to help explain the steps to solving an equation when you are only given the number of moles for one reactant
I need help for these questions... I do it tho, but some of them are wrong :/
1) The empirical formula of styrene is CH; the molar mass of styrene is 104.14 g/mol. What number of H atoms present in a 4.50g sample of styrene?
my answer is 8 because the ratio between C and H in styrene is...
Magnesium burns in oxygen gas to produce magnesium oxide. What mass of magnesium will react with a 0.25 L container of oxygen gas at 80oC and 770 mmHg? :confused:
I need to use stoichiometry to set up the pronlem and PV=nRT to solve.
I have three possible solutions, but I don't know...
Homework Statement
Given the balanced equation 2Al(NO3)3 + 3Mg ==> 3Mg(NO3)2 + 2Al , if 54.1 g of aluminum nitrate is reacted, what mass of magnesium nitrate is produced?
2. The attempt at a solution
I've been given an entire packet dedicated to stoichiometry, but nothing in here covers...
HELP! I've been having problems with Chemistry the past semester and a half, but stoichiometry is the hardest thing yet. Here's the problem:
Aluminum oxide is formed from the reaction of metallic aluminum with oxygen gas. How many moles of Aluminum are needed to form 3.4 moles of Aluminum...
Homework Statement
What is the molarity of 50.0mL sample of aluminum sulfite when it is reacted with 3.00M solution of barium chloride? The product of this double replacement is aluminum chloride and barium chloride.
Homework Equations
The first thing i did was balance(all number after...
This is the question:
How many phosphorus atoms are contained in 8.75 moles of H2P2O7? Put your answer in E-format with 1 number before and 2 numbers after the decimal place. e.g., 6.02 x 1023 would be input as 6.02E23.
the answer is : 1.05E25 (1.05 × 1025)
I really have no idea...
I need some help with this question.
A piece of chalk (mainly calcium carbonate) is placed in 250 mL of 0.293 M HCl. All the CaCO3 reacts, realising CO2 gas, and leaving a clear solution. 50.00 mL of the solution is pipetted into another flask. 87.1 mL of 0.0567 M NaOH is required to titrate...
I did this a bunch of times and did not understand what to do. Hopefully someone can shed some light. Our prof gave us hints, but they aren't really helping.
A mixture of KCr(SO3)2 and its hydrate KCr(SO4)2.12H2O has a mass of 1.6336 g. After heating (driving off water), the mass is 1.4659 g...
This is the full question:
Suppose you roast 2.00kg of Fe3S4. The equation:
4Fe3S4 + 25 O2 --> 6Fe2O3 + 16SO2.
a) How many kg of Fe2O3 will be produced?
b) How many kg of SO2 will be produced?
c) How many litres of air at 25 degrees C are required for roasting? Assuming air has 23% O2...
hello, i hope someone can help me.
i have a few questions.
The elements sulfur and chlorine react to give disulfur dichloride according to the equation:
S8 + 4Cl2 --> 4S2Cl2.
There are 0.5987 mol S8.
a) How many moles of Cl2 are needed for complete reaction?
b) What mass of S2Cl2 in...
Aluminum oxide is formed from the reaction of metallic aluminum with oxygen gas. How many moles of Aluminum are needed to form 3.4 moles of Aluminum oxide?
Hint: This is a simple ratio problem. Just use the molar ratio from the balanced equation. This was covered in 5.09. Mass is not involved...
I need some help with a stoichiometry problem from my basic Chem class.
Here it is: For the reaction: 2S(s) + 3O2 -> 2SO2(g)
How many moles of SO3 will be produced from 2.0 mol O2 and excess S?
This seems like a very simple conversion from moles O2 to moles SO3 - to which I have an answer...
Can someone show me how to calculate the number of moles of a given compound's molecules when given the mass in grams of the compund sample?
I am kind of confused by this because at first I thought it just asked for me to convert the grams into moles, but that isn't exactly what is being asked.
Hi. I need help on a stoichiometry problem:
When a particular hydrocarbon was burned in air, 0.467g of CO, 0.733g of CO2, and .450g of H2O were formed.
The question asks me to find the empirical formula of the hydrocarbon and the number of grams of O2 used in the reaction. The answers are...
Here is the example I was given:
------------------------------
Example:
How many liters of hydrogen gas can be produced at 290 K and 2.5 atm if 40.0 g of sodium react with excess water according to the following equations:
2 Na(s) + 2 H2O(l) --> 2 NaOH(l) + H2(g)...
Please help me I am so lost!
Here's the lesson. My writing is in Blue.
Where should I start? I am that confused; I feel like :cry:
Thanks for your help!
Hey there, I've been trying for the past 45 minutes to work on my online homework but I have made hardly any progress. Here are the 2 problems I'm having trouble with:
1- Calculate the number of molecules of NBr3 in 37.5 g NBr3. Use a molar mass with at least as many significant figures...