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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My question is about stoichiometry, limiting reagent problems [closed]

So I'm really struggling with this particular concept of these problems. I know how to convert to moler mass and all that, but I don't know how to do the ratio part, I can do them when the ratio is 1/...
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906 views

Moles of Sodium Peroxoborate

The question involves the addition of $\pu{0.15 g}$ of an already prepared sample of sodium peroxoborate which is added to $\pu{100 mL}$ of $\pu{1 M}$ $\ce{H2SO4}$ and $\pu{2 g}$ of $\ce{KI}$. The ...
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1answer
467 views

Find the Relative Error in the Mass of the Product

I have the following question, A student was given the assignment of $4.00$ $\pu{mL}$ of $0.50$ $\pu{M}$ $\ce{KI}$ with $16.00$ $\pu{mL}$ of $0.50$ $\pu{M}$ $\ce{Pb(NO3)2}$ in a stoichiometry ...
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1answer
139 views

Grams of bicarbonate vs realeased CO2?

So, it's been a good two years since I've done chemistry and I have my first university lab in a few days and I'm sort of freaking out because I can't even remember how to do stoichiometry properly. ...
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1answer
87 views

Why one gramm of O and one gramm of O2 icludes same amount of oxygen atoms? [closed]

So there is a problem I can't understand why one gram of O and one gram of O2 includes same amount of oxygen atoms.
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Atomic weights of non-molecular and non-stoichiometric compounds [duplicate]

Consider a composition such as $\ce{FeCo4Sb12}$. The atomic weight for a mole of substance is usually simply calculated by looking up the atomic weights (g/mole) for each involved element and adding ...
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926 views

What is the analogue of “molecule” for ionic compounds?

In a system, if we have $\pu{18 g}$ of $\ce{H2O}$ ($M_\mathrm r = 18$), we can say we have a mole of water molecules or $6 \times 10^{23}$ molecules. But in another system, if we have $\pu{342 g}$ of $...
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What's the difference between reactant, excess reactant and limited reactant in a balanced equation?

In some reactions, the reactant is mentioned as being "excess". For example, "phosphorus pentoxide forms in excess oxygen" or "pentahalides form with excess halogen". But since the balanced equation ...
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Calculate the number of atoms of oxygen present in 1.3 mol of sulfuric acid

Calculate the number of atoms of oxygen present in $\pu{1.3 mol}$ of $\ce{H_2SO_4}$ 1 mol has $6.02\times 10^{23}$ atoms So $\pu{1.3 mol}$ must have $1.3 \times 6.02 \times 10^{23} = 7.826 \times 10^...
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Conservation rule in closed systems

In a closed system the reacting species interconvert but do not leave the system. Therefore the amounts of different species in the system would be bound by a conservation rule. A simple example: ...
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693 views

Why is the rate of a reaction proportional to the concentrations of reactants raised to their stoichiometric coefficients?

Consider a gaseous state elementary reaction $$\ce{aA(g) + bB(g)} \overset{k_\mathrm{f}}{\underset{k_{\mathrm{b}}}{\ce{<=>}}}\ce{ cC(g) + dD(g)}$$ I know that for this reaction, $$\Delta G = \...
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if you have 2.5 * 10^21 atoms of magnesium how many moles do you have? [closed]

If you have $\pu{2.5 * 10^21}$ atoms of magnesium, how many moles do you have?
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1answer
182 views

Calculating molar mass of an oxidant by iodometry

I am stuck on a question from the Australian Chemistry Olympiad involving molar mass, shown here: BTW, this whole paper is available online for free, and is distributed by its owners for free. Just ...
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1answer
10k views

How to calculate the vapour density of a mixture?

I have a gaseous mixture of $\ce{H2}$ and $\ce{CO2}$ which contains $66\%$ by mass of $\ce{CO2}$. I have to figure out the vapour density of the mixture (defined as mass of a certain volume of a ...
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76 views

How do I know how many molecules a solute will split into when it dissolves in a solvent?

I'm in high school and I'm learning about freezing point depression and boiling point elevation. I've been given this chemistry problem: Acetic acid has a boiling point elevation constant of 2.93 ...
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1answer
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How to calculate mass produced when a given gas is burned?

The equation below represents combustion of methane ($\ce{CH4}$, $\pu{16.04 g/mol}$). Balance the equation, and calculate the mass of water ($\pu{18.02 g/mol}$) formed when $\pu{40.0g}$ of methane is ...
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Need help with stoichiometry problem

I'm pretty new to chemistry and I've been stuck on it for hours. Question: $\pu{10g}$ of the hydroxide of a metal on ignition gave $\pu{8g}$ of oxide. The equivalent weight of the metal is: a) $\pu{...
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489 views

Why is there an increasing solubility in water for chlorides, chlorates, perchlorates in that order?

According to Wikipedia $\pu{100 mL}$ of water dissolve at $\pu{25 ^\circ{}C}$ about $\pu{35 g}$ of $\ce{NaCl}$ (1), but about $\pu{79 g}$ of $\ce{NaClO3}$ (2), and around $\pu{210 g}$ for $\ce{NaClO4}$...
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253 views

Parts Per Million

I am trying to calculate how many milliliters of a solution I cannot exceed to create $\pu{200ppm}$ in the air of isopropyl alcohol. The $\pu{26ml}$ bottle of solution is 70% isopropyl alcohol. Using ...
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774 views

Balanced equation for the hydration of cyclohexene to synthesise cyclohexanol [duplicate]

I'm trying to determine the full balanced equation for a hydration of cyclohexene to synthesise cyclohexanol using concentrated sulfuric acid as catalyst and distillation as the extraction method. I'm ...
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740 views

Finding the molar concentration of reactant used

We were given this problem at my university, and I can't seem to figure out how it was solved. The question says we have $\ce{NaHCO3}$ and 100 ml of $\ce{HCl}$ react and one of their products is $\ce{...
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How can I convert weight percentage of calcium chloride hexahydrate to calcium chloride dihydrate? [closed]

I have a chemical formula with $27\%$ $\ce{CaCl2.6H2O}$ and $43\%$ water with the balance of $30\%$ being other chemicals. I want to convert the $\ce{CaCl2.6H2O}$ and water percentage to $\ce{CaCl2....
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How is the the law of chemical equivalence defined and what are its limitations?

I've heard that the law of chemical equivalence states that the gram equivalence of each of the reactants equals the gram equivalence of each of the products. But I'm facing difficulties in ...
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1answer
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In a mixture of NaOH and Na2CO3, why doesn't phenolpthalein change its color until Na2CO3 is half neutralised?

Let us consider a mixture of $\ce{NaOH}$ and $\ce{Na2CO3}$. Based on what I have understood, double titration works in the below manner : Phenolpthalein turns pink when added to the mixture. As $\...
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1answer
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Calculate the molarity of Na+ ions in 20 mL of a .130 M solution of Na2Cr2O7?

The answer is $\pu{0.260 M}$, but I keep getting $\pu{0.0052 M}$ because I thought the right way to do it was by multiplying $\pu{0.130 M}$ by $\pu{0.02 L}$, then multiplying by $2$ moles of $\ce{Na+}$...
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How to calculate atoms of *each* element in a compound

I am trying to do the following exercise in a chemistry workbook. I have searched over internet but I couldn't find or understand it. How many atoms of each element are found in: 5 moles $\...
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How to determine an unknown metal based on the reaction products with oxygen and fluorine?

The following question is, as it will probably be obvious, a homework question, however I have absolutely no idea how to progress with it beyond what I have already done. This is the question: $\pu{...
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1answer
3k views

Equivalent weight for CaO

I was wondering how I'd go around calculating the equivalent weight of CaO. From my knowledge, the EW of a compound is its (given mass )/(valence factor, n). Since CaO has no charge and no change in ...
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1answer
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How much KMnO4 is required for the complete oxidation of ferric/ferrous oxalate in acidic medium?

Find out the amount of $\ce{KMnO4}$ required for the complete oxidation of $\pu{5 mol}$ of an equimolar mixture of ferric oxalate and ferrous oxalate. I understand that $\ce{MnO4-}$ will be oxidised ...
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On what factors does the true reaction Stoichiometry depend when there are multiple valid options?

Consider the following unbalanced reaction: $$\ce{XeF4 + H2O -> Xe + XeO2 + HF + O2}$$ There are six variables to be solved, but only four equations linking them. I solved the set of equations ...
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63 views

Molar ratio of two oxides of the same metal

A certain "metal oxide" is made of the oxides $A$ and $B$ of the same metal. In the oxide $A$, the metal is divalent, and in B, the metal is tetravalent. By reduction with hydrogen of a quantity $a$ ...
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1answer
48 views

Chemistry Calculation Dilutions of Acid

I was presented with the following problem in my lecture and I am confused as to what to do. You are required to prepare $\pu{250 cm3}$ of $\pu{0.100 mol dm-3}$ HCl by diluting $\pu{0.600 mol dm-3}...
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1answer
571 views

Precipitation reaction stoichiometry?

I have a question where I do not understand the final step to solve...here it is: What will be the Strontium ion concentration remaining after 30.0 mL of 0.10 M Na2SO4 solution are added to 70.0 mL ...
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1answer
194 views

Oxide and chloride of a metal [closed]

I found this problem: The oxide of a metal contains 60.0% metal and the chloride of the same metal contains 25.26% metal (in mass percents). What are the possible formulas for the oxide and the ...
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1answer
145 views

Why doesn't hydroxide concentration equal concentration of carbonic acid and bicarbonate in a sodium bicarbonate solution?

To find the pOH of solution of $\pu{0.42 M}$ of $\ce{NaHCO3}$, given a $\ce{Kb}$ of $\pu{2.4E-8}$, my solution manual does the following steps: Reaction is similar to : $\ce{HCO3- + H2O <=> ...
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1answer
184 views

How to balance the redox reaction between bismuth(III) sulfide and nitrate anion?

I have to solve the following redox reaction which occurs in an acidic environment, using the half-equation method. $$\ce {Bi2S3_{(s)} + NO3-_{(aq)} -> BiO3-_{(aq)} + SO4^2-_{(aq)} + NO_{(g)}}$$ ...
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491 views

Calculating stoichiometry of a reaction between xenon and fluorine

Xenon and fluorine were mixed in a 1:1 ratio by volume and sealed in a vessel attached to a barometer. After some time, crystals were found to have formed on the walls of the vessel and the barometer ...
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3answers
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Why is it wrong to calculate the amount of oxygen directly from the products of a combustion reaction?

I've been stumped by a question in my textbook concerning combustion analysis. A $\pu{0.5438g}$ sample of a liquid consisting of only $\ce{C}$, $\ce{H}$, and $\ce{O}$ was burned in pure oxygen, ...
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224 views

Calculating a theoretical degree of polymerisation of ethylene oxide

This is the problem: Researchers add 88 grams of ethylene oxide. This reacts fully to 92 grams of poly ethylene oxide. Calculate the degree of polymerisation. I thought: molecular weight of ethylene ...
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2answers
274 views

Help with uncertainties

When diluting a mixture of two reactants with lets say a 100ml of H2O, how do you add this to the uncertainties of the concentrations of the reactants? Should the relative uncertainty of the added H2O ...
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1answer
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How to determine the theoretical concentration of the acetic acid solution in mol dm-3 of vinegar

How do you determine the theoretical concentration of an acetic acid solution in mol dm-3 of vinegar that is 5% acetic acid, knowing that the density of vinegar is 1.000g cm-3?
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342 views

What is the best approach to balance this equation? Why I cannot do it efficiently?

What is the best approach to balance this equation? $$\ce{CO2 + H2O <--> C2H2 + O2}$$ I did it at first this way and I was not successful: \begin{align} \ce{4CO2 + H2O &<--> C2H2 + ...
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1answer
179 views

Why does one of Dalton's compound elements with oxygen and phosphor consists of four atoms instead of two?

I stumbled across a peculiar detail while reading the chapter about the Chemical Revolution in Bowler and Morus' book Making Modern Science. According to this book, Dalton argued that compound ...
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52 views

Theoritical amount of Sodium Bicarbonate

I have to find the theoretical amount of sodium bicarbonate. The steps I followed in order to produce it are: 15g $\ce{NaCl}$ are added to a beaker. Then we add 87.5 mL of $\ce{NH3}(12M)$ We add 115g ...
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Finding the formula of an alcohol with a given molecular mass

Deduce the molecular formula of the alcohol that has molecular mass 158. I tried dividing this molecular mass (158) by the molecular mass of ethanol (46) to get a ratio, and then multiply the formula ...
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2answers
146 views

If there are multiple bases in solution and a strong acid is added, will both bases react?

For example, if there is one mole of carbonate ions ($\ce{CO3 ^2-}$) and sulfate ions ($\ce{SO4 ^2-}$) in a solution, and one mole of hydrochloric acid ($\ce{HCl}$) is added, will the one mole of ...
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1answer
2k views

Calculation of empirical formula from elemental analysis

A compound contains 40.0% Carbon, 6.7% Hydrogen, and 53.3% Nitrogen (by mass). Calculate the empirical formula. I'm getting $\ce{C7H14N8}$, but my professor says it is $\ce{CH2N}$. Which is the ...
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Can equivalent mass be more than the molecular mass? Can it be applied to radical reactions?

Consider a reaction involving radicals: $$\ce{CH3^. + Cl^. -> CH3Cl}$$ Is the definition of equivalent mass applicable here? If yes, how? Are there reactions where equivalent mass of a reagent ...
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571 views

Neutralization Reaction problem

$\frac x4$ equivalent of $\ce{NaAl(OH)2CO3}$ is neutralized by $x$ equivalent of $\ce{HCl}$ Milliequivalent of $$\ce{HCl}=\mathrm{{160}\times{0.25}\times{1}\times{40}}/100=16$$ $1$ is for one $\ce{H+...
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1answer
240 views

'Rate' in the rate law

I am slightly confused about what the rate is that is given by the rate law. Is it the rate of reaction (I.e. the rate of loss of reactant or formation of product divided by its stoichiometric ...