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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KSP Equilibrium determining Mass

Suppose that 50.0mL of 0.100M AgNO3 were added to 50.0mL of 0.5M NaCl. What is the weight of AgCl will be formed? What would be the final concentration of the Ag+ ions? Hey guys. I am currently ...
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Limiting Reactant- copper (II) chloride and aluminum metal [closed]

What is an easy, VISUAL observation you could make to determine which reactant is in EXCESS vs. which reactant is the LIMITING REACTANT when you mix an aqueous solution of copper (II) chloride with a ...
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Copper (II) Chloride and Aluminum Limiting Reactant and % Yield [closed]

When you mix an aqueous solution of copper (II) chloride with a solid piece of aluminum metal, what is an easy, VISUAL observation you could make to determine which reactant is in EXCESS vs. which ...
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Recycling Reactor

Given the synthesis reaction of methanol: $$\ce{CO2 + CO + 5H2 -> CH3OH + H2O}$$ In a reactor with a recycle stream contains all 4 components. When calculating the energy of reactants, do we ...
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Do you divide by 16, or by 32 when finding the amount of moles in Oxygen gas (magnesium oxide experiment)? [closed]

Magnesium + oxygen gas makes magnesium oxide. The formula for this is 2Mg + O2 --> 2MgO. If we had 0.18g of Magnesium and 0.18g Oxygen, to find the moles of both masses you divide by the molar mass. ...
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39 views

Calculate the percent composition of a sodium carbonate/sodium bicarbonate mixture

In a lab, we titrated a solid mixture of sodium carbonate and sodium bicarbonate with $\pu{0.1 M}\ \ce{ HCl}$. We are asked to calculate the percent composition by mass of sodium carbonate and sodium ...
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2answers
37 views

What does it mean to balance a redox reaction in acidic or basic mediums? [closed]

Until now it was clear to me what balancing a reaction was. Balancing redox reaction also make sense to me. What does it mean to balance a redox reaction in acidic or basic medium?
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Application of limiting reagents and acid-base stoichiometry

I'm having a bit of trouble with the latter questions of this problem. $\pu{15.0 mL}$ of $\pu{1.4 M}$ $\ce{HCl}$ was mixed with $\pu{1.00 g}$ of $\ce{CaCO3}$ until all the solid had dissolved. The ...
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1answer
41 views

Constructing chemical equations [closed]

When constructing chemical equations, how can you work out the subscript of each product. For example: $$\ce{3Ca + N2-> Ca3N2}$$ How do I know that it's $\ce{Ca}$ with a little 3 and N with a ...
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1answer
12k views

How to balance the reaction equation of potassium permanganate, calcium oxalate, and sulfuric acid step by step?

I have been desperately trying to balance the following equation, and finally (ultima ratio) used an online program to get it done (posted the same question there as well). $$\ce{KMnO4 + CaC2O4 + ...
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Preparation of Ca/PO4/acetate solution

EDIT: This is not a homework problem and we need this for an exploratory study on teeth demineralization. There is further work planned around this activity, which may not be relevant to the question. ...
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What is the mass of ozone present in 10.6 g of Na2CO3?

I got a question in my textbook asking for the mass of oxygen present in 10.6 grams of $\ce{Na2CO3}$. Why are they asking about the mass of oxygen? Does this refer to $\ce{O2}$? Shouldn't it be the ...
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3k views

How to assign oxidation number of sulfur in thiocyanate anion?

Recently I was trying to balance a redox chemical equation: $$\ce{CuSCN + KIO3 + HCl <=> CuSO4 + KCl + HCN + ICl + H2O}$$ The equation is in principle simple to solve; one element ($\ce{I}$) ...
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1answer
102 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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2answers
60 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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94 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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Balanced equation for Schweizer's reagent production?

In Thompson's Illustrated Guide to Home Chemistry Experiments the chemical formula for Schweizer's reagent is represented as $\ce{[Cu(NH3)4](OH)2}$ (although Wikipedia represents it as $\ce{[Cu(NH3)4(...
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Molar ratios not leading to complete reaction in Schweizer's reagent production

In my home lab, I've reacted $\ce{Cu(OH)2}$ with aqueous ammonia to produce Schweizer's reagent. However, I'm surprised by the amount of ammonia required to react with this amount of $\ce{Cu(OH)2}$. ...
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How to calculate the number of atoms of each element in a urea?

I have a stoichiometry question which I answered incorrectly and I am not sure where I went wrong. The question is as follows: Urea, $\ce{(NH2)2CO}$, is used for fertilizer and many other things. ...
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1answer
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Rate Expression with two products

Consider the two following cases Case 1: Two Same Products Given the following chemical reaction, $$A + B \rightarrow C + C$$ where C are radicals, therefore I am not writing $2C$ on the right ...
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1answer
58 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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How to calculate valence factor (n-factor) for a element?

Suppose I am given some reaction in which $$\ce{C6H12O6 -> CO2}$$ and I want to calculate n-factor for this reaction to ultimately calculate equivalent weight of carbon for this reaction. Since $$...
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1answer
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What is the amount of nitrate ions in 20 g of Fe(NO3)3?

What is the amount of nitrate ions in $20.0\:\mathrm{g}$ of $\ce{Fe(NO3)3}$? The chemical formula for the nitrate ion is $\ce{NO3}$, I think. The molar mass of $\ce{Fe(NO3)3}$ is $242~\mathrm{g~mol^{...
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1answer
878 views

what is the mass of chromium in this sample?

If the total number of atoms in a sample of potassium dichromate is $2.13\cdot10^{24}$ , then the amount of chromium in this sample is? the answer that I've come up with is $367.64\ \mathrm g$ but in ...
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1answer
7k views

How to find the number of hydrogen atoms in 0.5 mol of hydrogen gas?

How do I calculate the number of hydrogen atoms in $\pu{0.5 mol}$ of hydrogen gas? I presume the answer would probably somehow use the equation $$n = \frac{m}{M},$$ where $n$ is the amount of ...
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Law of Multiple Proportions: What is the significance of small whole numbers?

I'm new to Chemistry and in my textbook, it describes the Law of Definite Proportions (aka Proust's Law) and then goes on to describe the Law of Multiple Proportions. The example they give is carbon ...
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1answer
63 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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111 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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1answer
82 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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Air contain 20 % O2 by volume. How many cm³ of air will be required for oxidation of 100 cm³ of acetylene?

Air contain 20 % $\ce{O2}$ by volume. How many cm³ of air will be required for oxidation of 100 cm³ of acetylene? (a) 1064 cm³ (b) 212.8 cm³ (c) 500 cm³ (d) 1250 cm³ Answer: (d) My ...
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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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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
219 views

Multiple solutions in the balancing of redox reactions

While looking at the reaction between potassium permanganate and hydrogen peroxide in the presence of sulfuric acid a friend and I were attempting to find a general equation to yield the coefficients ...
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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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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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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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2answers
2k views

Sodium azide to Nitrogen ratio in airbags

I've been given this question and I don't know how to solve it. Airbags are designed to protect the occupants of a car during a collision. They use the decomposition of sodium azide, $\ce{NaN3}$. ...
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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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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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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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110 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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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
58 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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1answer
41 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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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
38 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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31k views

How to find the molecular formula for a hydrocarbon compound from known combustion products?

What is the molecular formula of a compound containing only carbon and hydrogen if combustion of $1.05~\mathrm{g}$ of the compound produces $3.30~\mathrm{g}~\ce{CO2}$ and $1.35~\mathrm{g}~\ce{H2O}$ ...
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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
85 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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404 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 ...