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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27 views

Finding mass of MnF3 is produced in a reaction

The question is as follows: If $\pu{1.23 g}$ of $\ce{MnI2}$ reacts with $\pu{25.0 g}$ of $\ce{F2}$, what mass of $\ce{MnF3}$ is produced? $$\ce{2 MnI2 + 13 F2 -> 2 MnF3 + 4 IF5}$$ I think this ...
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22 views

Finding amount of CaCl2 produced in a reaction

The question is as follows: Calcium reacts with chlorine gas to form solid calcium chloride. If $\pu{5.3g}$ of calcium reacts with excess chlorine. Find out how much calcium chloride will be ...
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1answer
22 views

Calculation of Density change [closed]

How can I find out the change in density of water when $\pu{4mg}$ of $\ce{Ca(OCl)2}$ is added to $\pu{1L}$ of water?
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52 views

How to determine the composition of a gas mixture after a combustion?

The problem is as follows: A mixture of gases consisting of $\ce{CH4}$ and $\ce{C2H4}$ is let to pass over red hot $\ce{CuO}$. Then $\pu{0.6g}$ of $\ce{H2O}$ is collected along $\pu{1.185g}$ of ...
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1answer
56 views

Oxidation of toluene to benzoic acid [closed]

On Wikipedia I found the reaction of the oxidation of toluene to benzoic acid: $$\ce{5 C_6H_5CH_3 +6 KMnO_4 +9 H_2SO_4} \to \ce{5 C_6H_5COOH +14 H_2O +3 K_2SO_4 +6 MnSO_4}$$ which involves $35\, \ce{...
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17 views

Stoichiometry Limiting Reagent and Mass of One of the Products

0.3 g of ethanoic acid (CH3COOH) reacts with a solution of containing 0.00450 moles of sodium hydrogencarbonate. (I'm not so sure what is missing in the question after "of" in solution of containing) ...
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1answer
48 views

Question On Balancing [closed]

I recently worked on a lab which involved the following reaction: $$\ce{HCl(aq) + CuO(s) -> CuCl2(aq) + H2O(l)}$$ In my description of the reaction I wrote the following "The equation shown ...
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1answer
39 views

Calculate the mass of iron in the original mixture!

I seemingly can't solve the following problem, I've spend over 30 mins on it, no progress, can any of you geniusses give a step by step solution to me? Thank you so much Problem: A mixture of ...
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1answer
39 views

Finding molecular formula with limited information given

I have recently stumbled upon a question I can't seem to solve : Chlorine can also be used to synthesise a bromine-containing oxoanion that is mainly used in continuous or batch dyeing processes. ...
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Does it make a difference to use moles, grams or liters to find the required mass of an element from a reaction with water vapor?

I'm confused if the required mass from a two step reaction can be found using moles, grams or liters. This happened when attempting to solve a gas reaction with a solid. The problem is as follows: ...
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1answer
17 views

How does the vapor pressure in a vessel affects the total pressure after a combustion reaction?

The problem is as follows: A sealed container of $3\,L$ in capactity is filled with hydrogen and oxygen at $314\,torr$ each one at a temperature of $27^{\circ}C$. A spark produces the reaction ...
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1answer
23 views

How do you find the bond enthalpy from an equation?

Which equation represents the $\ce{N-H}$ bond enthalpy in $\ce{NH3}?$ $$ \begin{align} &\textbf{A.} &\ce{NH3(g) &-> N(g) + 3 H(g)}\\ &\textbf{B.} &\ce{1/3 NH3(g) &-> ...
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1answer
46 views

What is Meant by Mole Percent?

I am attempting to interpret an experimental section on a scientific paper. The paper calls for 0.51 mmol of 3,5-dimethoxy phenol, 1.0 mmol of 3-methyl-3-butenal, 5 mol% of phenylboronic acid, 20 mol% ...
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1answer
35 views

A “function of proportionality” in a rate law [closed]

I am currently studying rate laws and the determination of the order of a reaction. So first-order reactions remind me of linear functions $f(x)=kx$ while second-order reactions remind me of quadratic ...
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I have a solution of citric acid, tartaric acid, water and glucose. How do I find the concentration of the citric acid present in the solution?

If I try to find the concentration of citric acid through back titration or reverse titration, the base I would use, like NaOH, would react with both acids to form sodium citrate and sodium tartrate, ...
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1answer
38 views

How are atomic masses determined? [closed]

The atomic mass (ma) is the mass of 1 atom of an element. Elements have isotopes. Therefore, there must be an atomic mass (ma) associated with each isotope of an element. How do we know the atomic ...
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1answer
62 views

Is there a difference between (HO)2 and H2O2?

To me, it looks like the same thing. Is (HO)2 and H2O2 the same compound? When performing stoichiometric calculations, do they get treated the same?
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1answer
55 views

Finding percent weight

I have a mixture of $\ce{NO2(g)}$ and $\ce{N2O4(g)}$ at $63\ \mathrm{^\circ C}$ and $750\ \mathrm{mmHg}$. I need to find the weight percent of the first compound. Density $d=1.98\ \mathrm{g/L}$. I ...
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138 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
49 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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1answer
42 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
56 views

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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2answers
162 views

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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54 views

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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1answer
41 views

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
78 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
149 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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55 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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57 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
84 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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33 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
52 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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96 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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71 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
51 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
133 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
59 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
51 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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21 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
43 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
40 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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78 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
455 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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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
98 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
112 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 ...