Questions tagged [stoichiometry]

Stoichiometry refers to the relationship between the amounts of substances of the reactants and the amount of substances of the formed products. This tag should be used for specific questions about chemical reaction equations.

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1answer
23 views

Chemical reaction balance - High pH carbonic acid and calcium iodide solution [on hold]

Is it possible to write the following chemical reaction in one compact balanced form instead of being two separate sections at the right hand side? $\ce{CaI2(aq)}$ + $\ce{2NaOH(aq)}$ + ($\ce{2H+}$ + $...
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49 views

Equivalent weight of salts [on hold]

I was solving, my homework question, using chemical equivalence, question was this $448\ \mathrm{ml}$ of $\ce{SO2}$ at ntp are passed through $100\ \mathrm{ml}$ of a $0.2\ \mathrm N$ solution of $\...
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26 views

How does air being saturated with water affect combustion reaction in coke oven [on hold]

I am doing a question where A coke oven gas contains 40% CH4, 15% H2 and 45% CO. The feed air is saturated with water vapour at 80c. What is the volume of dry air required to completely burn 1m^3 (...
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0answers
22 views

Combustion problem, empirical and molecular problem set up? [closed]

I have a problem setting up the overall problem below I know the answer to part A (C2H3O3 or tartaric acid). Whenever work it out I never get the correct formula. I'm not sure if I'm messing up on one ...
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0answers
34 views

Finding the maximum mass of copper(II) nitrate that can be produced from a given mass of copper [closed]

I have the following chemical equation: $$\ce{Cu(s) + 4 HNO3(aq) -> Cu(NO3)2(aq) + 2 H2O(l) + 2 NO2(g)}$$ The mass of copper in the equation is 0.6355 g. I am trying to find the maximum mass of ...
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25 views

Difference between relative atomic mass, molar mass, and atomic mass unit? [duplicate]

They have the same numerical value. For example, Hydrogen has relative atomic mass of 1.01, molar mass of 1.01 g/mol, and atomic mass unit of 1.01 u. What is the difference between relative atomic ...
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1answer
50 views

What is the physical meaning of the statements like “weight percentage of FeO in Fe”? [closed]

I have always had the notion of calculating weight percentage of Fe in FeO. It always seems that we are to calculate at times the weight percentage of FeO in Fe.Particularly when one weight percentage ...
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1answer
57 views

How do I solve this problem on mass balance from blast furnace iron making?

Question An ironmaking blast furnace produces hot metal of the composition: $\pu{93.6\%}$ $\ce{Fe},$ $\pu{2.1\%}$ $\ce{Si},$ $\pu{3.6\%}$ $\ce{C},$ $\pu{0.7\%}$ $\ce{Mn}.$ The composition of the ...
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40 views

Why are the equilibrium exponents stoichiometric when the rate law's are not? [duplicate]

I'm learning about rate law and equilibrium, and the textbook really hammers in that the exponents for the rate law must be determined experimentally - you can't just use the coefficients from the ...
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17 views

Determining formula of potassium molybdate from the amount of metal deposited during electrolysis

$\ce{K2MoO_n}$ in an acidified solution is electrolysed, $\pu{0.112 L}$ of oxygen is liberated and $\pu{0.32 g}$ of $\ce{Mo}$ is deposited (Atomic mass = $96$). Find $n.$ Now for this, I calculated ...
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17 views

Question based on finding impurity of a sample of Sodium bicarbonate

12.5g of commercial sodium bicarbonate gives 3 g of carbon dioxide. What is the percentage in purity in the sample? $$\ce{2NaHCO_3 -> Na_2CO_3 + CO_2 + H_2O}$$ I have solved this question, but I ...
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1answer
77 views

How to calculate the relationship between the pressures of zinc, carbon monoxide, and carbon dioxide based on mole balance?

Zinc oxide is reduced at a constant temperature in a closed reactor using $\ce{ZnO(s)}$ and $\ce{C(s)}$ as the only starting materials. The following reactions are assumed to be at thermodynamic ...
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29 views

How do you find the heat capacity ratio of combustion products?

For example, if gaseous oxygen $(O_2)$ and paraffin wax $(C_{32}H_{66})$ were to stoichiometrically combust at STP, how would one go about finding the heat capacity ratio ($\gamma={c_p \over c_v}$) of ...
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1answer
47 views

Why do we need to use oxidation number in order to balance a complex chemical reaction easily in an acidic or alkaline medium? [closed]

I have been trying to balance this chemical reaction in an "acidic" medium without using oxidation number or ion electron method: [$\ce{Fe^2+ + Cr2O7^2- -> Cr^3+ + Fe^3+}$]. Though I can balance ...
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0answers
49 views

Finding initial mole fraction of ammonia in ammonia-hydrazine mixture using thermodynamic parameters before and after thermal decomposition

A mixture of $\ce{NH3}$ and $\ce{N2H4}$ is placed in a sealed container at $\pu{300 K}$. The pressure within the the container is $\pu{0.6 atm}$. The container is heated to $\pu{1000 K}$ where the ...
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30 views

Why decanted solution should be colorless when determining formula of unknown chloride?

I was following the guide “Stoichiometric Determination: Empirical Formula of Copper Chloride”. Under the Procedure section the following reaction is given: Producing solid $\ce{Cu}$ from a $\ce{Cu(...
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1answer
40 views

What is the cause of decrease in volume of gaseous mixture in the following problem? [closed]

I am studying Gaseous State. The problem says: A mixture of gas contains $\ce{N2}$ and $\ce{C2H2}$. $\pu{20 \\mL}$ of this mixture is added to $\pu{70\\mL}$ of $\ce{O2}$ and combustion is allowed to ...
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1answer
69 views

Will the volume occupied by a mixture of nitrogen and water be same as the volume occupied by them individually?

I am currently studying gaseous state and I encountered the following problem. A container with a volume 3 liter holds $\ce{N2(g)}$ and $\ce{H2O(l)}$ at $\pu{29 ^\circ C}$. The pressure is found to ...
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2answers
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Proust's law/Laws of definite proportion [closed]

As per laws of constant proportion/Proust's law,Ratio of elements by mass is always constant. But in case of H2+O2 →H2O Here when the chemists might have measured H2 and O2 individually they might ...
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1answer
53 views

Balancing chemical reactions, issues of Gauss's elimination method [duplicate]

I am trying to balance some chemical reactions by using the Gauss' elimination method and I noticed that this method does not work if the creation of a matrix with exactly one degree of freedom is not ...
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2answers
46 views

How do I do stoichiometry for 2 limiting reactants

The Drano reaction produces sodium aluminate along with hydrogen gas. If a typical container of Drano weighs 500 g which is 35% by weight by weight sodium (l) hydroxide and 2.5% by weight aluminum, ...
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19 views

Methods and observations that help you achieve complete decomposition of a compound in decomposition analysis [closed]

Different chemicals decompose in different ways to give different observations, but they usually involve heating the compound to high temperatures. My question is that what are your lab techniques ...
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1answer
40 views

Why are yields of some chemical reactions so dependent on the stoichiometry of the reagents? [closed]

Back in chemistry class in high school I was working with a partner doing a chemical reaction. We measured the amounts of reagents well, but not perfect, and our yield suffered greatly. On the other ...
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1answer
31 views

What value should I use for P in the ideal gas equation for an unknown molar quantity?

I did a chemistry lab, in which baking soda and vinegar were reacted in a ziplock bag, and I was to calculate the proper quantity of reactants to fill the bag with CO2. The molar quantity of gas was ...
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39 views

What does “at%” mean and how it differs from “mol%”?

Sorry if my question is a bit obvious, but for some reason I'm getting confused with the percentages in this question: Concentration of $\ce{A}$ is $\pu{80 at\%}$ and concentration of $\ce{B}$ is $...
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1answer
242 views

Reaction between copper(II) iodate and iodide

I was attempting the following question from IChO 1989, which involved balancing of redox equations. One may just expect this to be a typical iodate-iodide redox reaction, usually employed in ...
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29 views

Two different answers obtained by balancing this chemical equation!! Somehow [duplicate]

This is the concerned equation: $\ce{ XeF4 + H2O -> Xe + XeO3 + HF + O2}$ This can be balanced as $\ce{6 XeF4 + 12 H2O -> 4 Xe + 2 XeO3 + 24HF + 3 O2}$ or $\ce{5 XeF4 + 10H2O ->3 Xe + ...
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1answer
54 views

Why do we use coefficients for RFM (relative formula mass) in atom economy? [closed]

Usually when calculating using moles = mass / RFM, the coefficient is not multiplied by a compound's RFM to calculate RFM. But in calculations for atom economy, the (balanced) coefficient of a ...
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1answer
57 views

Equivant mass of double salt

What is the equivalent mass of double salt like dolomite? And what if the double salt is hydrated? Is a double salt taken as a single unit while equating the gram equivalent in any reaction? For ...
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Mass of H2 in a balloon

Question A balloon of diameter $\pu{2 m}$ has a volume of $\pu{4190 dm^3}.$ It floats since it is given an up thrust equal to the mass of air it displaces. (Given: average $M_\mathrm{r}$ of ...
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1answer
253 views

How to calculate the equivalent mass of Na2S2O3? [closed]

Let us consider the following reaction $$\ce{I2 + 2 Na2S2O3 -> 2 NaI + Na2S4O6}$$ Now, in order to calculate the equivalent mass of $\ce{Na2S2O3}$, first I need to calculate it's $n$-factor which ...
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2answers
95 views

Complete combustion of mixtures

I am working on my scholarship exam practice (around high school and first year university level). I could actually solve the problem below but my solution is pretty time consuming. It would be ...
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2answers
51 views

Finding molarity of hyposulfite solution used in titration

$\pu{0.1 g}$ of $\ce{KIO3}$ is treated with excess $\ce{KI}$ solution. The liberated iodine required $\pu{44 ml}$ of $x$ molar hypo solution. Calculate the value of $x$. I have used the equivalent ...
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1answer
304 views

How to calculate the equivalent weight of KMnO4?

Let us consider the following reaction $$\ce{2 KMnO4 + 16 HCl → 2 KCl + 2 MnCl2 + 8 H2O + 5 Cl2}$$ Now, in order to calculate the equivalent mass of $\ce{KMnO4}$, first I need to calculate it's $n$-...
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2answers
281 views

Why the concentration with respect to time equation of a first-order reaction does not depend on the stoichiometric coefficient of reactant?

According to my Chemistry textbook (Chemistry by Raymond Chang 10th edition, pg 570), for a first-order reaction of the type $$\ce{A->product}$$ the rate is $$rate=-\frac{[\Delta A]}{\Delta t}$$ ...
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2answers
89 views

Finding the sum of coefficients of the reaction

What is the sum of the coefficients $(a + b + c)$ in the following reaction? $$\ce{x Zn + y HNO3} -> {a Zn(NO3)2 + b H2O + c NH4NO3}$$ Here if the equation is balanced we get 1 mol of $\ce{Zn}...
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3answers
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Shouldn't the “law of conservation of mass” prevent equations from being unbalanced in the first place? [closed]

How is it that a chemical reaction produces an equation, that is essentially an impossibility, according to the law of conservation of mass? If the law is true, shouldn't all chemical reactions ...
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1answer
85 views

Equivalents of Oxalic acid

In this question the answer key given is A and C. But i think that D should also be wrong because equivalents = molecular mass / n factor = $\frac{90}{2} = 45 \neq 40 $ I believe I am correct but I ...
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145 views

Degree of Hardness Numerical

To remove the temporary hardness from $5\ \mathrm L$ of $\ce{H2O}$ $5.6\ \mathrm{mg}$ of lime is required. Calculate the degree of hardness due to $\ce{Ca(HCO3)2}$ present in water. My attempt: $$ \...
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1answer
54 views

How can normalities be interchangeably used?

So I was doing the following question on stoichiometry . The part $\pu{1.80N}\ \ce{HCl}$ can also be written as $\pu{0.9 N}\ \ce{ H_2SO_4}$ but I don't understand why . $\pu{10 g}$ sample of 'gas ...
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What type of acid (and how much) needed to generate Chlorine Dioxide gas when added to Sodium Chlorite (for odor removal)?

I have several lbs of Sodium Chlorite (flakes), which I would like to use to generate Chlorine Dioxide gas in order to remove odors from rooms, autos, boats, etc. There are commercial products sold ...
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2answers
58 views

Determining amounts of product and excess reagent remaining post reaction

$$\ce{2FeS2 + 11/2 O2 -> Fe2O3 + 4 SO2}$$ Mass of $\ce{FeS2}$ is $\pu{600 g}$ and mass of $\ce{O2}$ is $\pu{800 g}$. Find the amounts of $\ce{Fe2O3}$ and $\ce{SO2}$ and the remaining amount of ...
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31 views

About the percentage yield and purity

I was wondering why all of the percentages like mass percent composition, percentage yield and percentage purity are calculated using masses. Wouldn't it make more sense to use number of moles of the ...
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1answer
78 views

Gravimetric analysis

In a gravimetric determination of phosphorus an aqueous solution of dihydrogen phosphate ion is treated with the mixture of ammonium and magnesium ions to precipitate magnesium Ammonium Phosphate. ...
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1answer
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Help with question about mols in reactions

Consider the following reaction $$\ce{4H2O + 5I2O4 -> 8HIO3 + I2}$$ If 0.167 mol of $\ce{H2O}$ is added to 0.200 mol of $\ce{I2O4}$ what amount (moles) of $\ce{HIO3}$ can be formed, it ...
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1answer
35 views

Finding simplest formula of a compound with following specifications

I ran into the following problem, wherein I'm asked to find the simplest formula of a compound containing $50 \%$ of element $X$ (atomic wt. 10) and $50\%$ of element $Y$ (atomic wt. 20). I know ...
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2answers
152 views

What does it mean to calculate hardness in terms of ppm of calcium carbonate? [closed]

PPM means per part million or milligram per litre of solution.Calculation of ppm for a given compound say $x \pu{gms}$ of $\ce{Ca(HCO_3)}$ in 1 liter of water would be done like $$ppm= \frac{1000\...
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0answers
54 views

Stoichiometry based on addition of simultaneous equilibria

I read on another equilibrium question that if two equilibria occur at the same time, then it is not accurate with actual stoichiometry to add the two equations and multiply the equilibrium constants $...
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2answers
124 views

Derivation of Gibbs free energy formula

Okay, so I'm trying to derive an important formula which states that - ∆G(r) = ∆G° + RTln( RQ ) where ∆G(r) is the instantaneous rate of change of Gibbs energy with ...
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1answer
57 views

Why coefficient doesn't change amount of substance

$\ce{3Mg + 2As -> Mg3As2}$ ($10\ \mathrm g$ of $\ce{Mg}$ and $10\ \mathrm g$ of $\ce{As}$) I don't understand why coefficient doesn't change the amount of substance, here's what I did: $n_{\ce{Mg}...