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.

Filter by
Sorted by
Tagged with
-1
votes
3answers
266 views

An aqueous solution of NaCl has a mole fraction of 0.21. What is the mass of NaCl dissolved in 100.0 mL of solution? [closed]

Work mole fraction of NaCl = 0.21/0.21+0.79 If there is 1 mol of total solution, there will be 0.21 mol NaCl and 0.79 mol H2O 0.21 mol NaCl = 12.27 g 0.79 mol H2O = 14.23 g this would yield a ...
1
vote
2answers
117 views

How much of Ag has formed on the Cu tile?

$\pu{9.547 g}$ $\ce{Cu}$ tile is added to an $\ce{AgNO3}$ solution. After some time, $\ce{Cu}$ was taken out of the solution, washed, dried and weighed. The mass appeared to be $\pu{9.983 g}$. How ...
1
vote
1answer
60 views

Mass fraction in a mixture of metal salts given the total mass of the metal

I am trying to solve a question in my study and I don't get the answer required. A mixture of $\ce{NaNO3}$ and $\ce{Na2SO4}$ weight $5.37$ grams, the $\ce{Na}$ = $1.61$ grams. What is the ...
0
votes
2answers
57 views

Determining the formula of zirconium oxide

I am doing the following question (from the 1988 HSC Chemistry paper): In the 19th Century the atomic weight of zirconium (Zr) was known but there was considerable doubt about the formula of ...
0
votes
2answers
99 views

Percent hydrogen and carbon [closed]

A 1 g sample of an organic compound was burned in a combustion analyzer and yielded 1.42 g carbon dioxide and 0.872 g of water. Calculate the percent carbon and hydrogen in the sample. From the ...
-1
votes
2answers
2k views

Finding mole fraction from molality

Calculate the mole fraction of ammonia in a $\pu{2.00 m}$ solution of $\ce{NH3}$ in water. What I know is that the formula for mole fraction is $$X = \frac{\text{no.-of-moles-of-solute}}{\text{(no.-...
1
vote
1answer
114 views

How does the pH of solutions of salts in which the cation is acidic and anion basic, depend only on the relation of their constants?

My book is not very explanative about it, I'm trying to get the equation: $$[\ce{H^+}]=\sqrt{K_\mathrm{w}\times\frac{K_\mathrm{a}}{K_\mathrm{b}}}$$ but I didn't succeed, can someone explain the ...
2
votes
1answer
423 views

What exactly is a reducing equivalent and what does it do?

I've encountered this term in the context of cellular metabolism, but I can't seem to find an explanation of what a reducing equivalent is or why it is named this way. Wikipedia was not really helpful,...
0
votes
1answer
55 views

Evaluate mass of salt needed to add to a buffer solution knowing only pH

This is an exercise taken from an old exam, I'm struggling with the resolution. To a solution of a generic weak acid $\ce{HA}$ were added $\pu{2.40 g}$ of a potassium salt of the $\ce{KA}$. The ...
0
votes
1answer
88 views

Determination of molecular formula of hydrocarbons by combustion analysis

So, I've this question in my textbook: $\pu{20 mL}$ of unknown gaseous hydrocarbon reacts with excess oxygen gas. It decreases by $\pu{30 mL}$ upon cooling down. It decreases farther $\pu{40 mL}$ ...
-1
votes
1answer
80 views

If the net ionic equation and complete equation balance differently, which one do you use? [closed]

Sometimes the full equation of a reaction and the net ionic equation balance out differently. If that is the case, which is the correct one to use? For instance, in the reaction between a solution of ...
0
votes
1answer
59 views

finding out fractions of ions(different valencies/charges) of an element in non-stoichiometric compounds

Analysis shows that nickel oxide has the formula $Ni_{0.98}O_{1.00}$. What fractions of nickel exist as $Ni^{2+} $and $Ni^{3+}$? What i did: Let the number of $Ni^{2+}$ and $Ni^{3+}$ atoms be $x$ ...
-1
votes
1answer
41 views

How to distinguish between iron and nickel based on the mass of precipitate formed with sodium hydroxide?

For the reactions shown below, we added $\pu{5.00 mL}$ of $\pu{0.0390 M}$ $\ce{NaOH}$ to a test tube containing one of the two cations $\ce{Ni^2+}$ or $\ce{Fe^3+}$ and recovered $\pu{0.00695 g}$ of ...
-1
votes
1answer
176 views

Finding the percent by mass of an unknown substance

I'm doing some chemistry homework and a the problem in question goes as follows: "A student performs an experiment to determine the percentage by mass of $\ce{MgCl2}$ in a $\pu{2.94g}$ sample of a ...
1
vote
1answer
26 views

How do I identify how many reactions are occurring when precipitating a mixture?

An example of a question is: After dissolving $x$ grams of a mixture of $\ce{Na2SO4}$ and $\ce{NaCl}$ in water, you add an excess of $\ce{BaCl2}$ solution. You filter off the precipitate which ...
0
votes
2answers
214 views

Calculate the concentration in milimoles per litre (mM) of a solution that is 20% H2SO4 by mass and that has a density of 1.198 g/L

Calculate the concentration in milimoles per litre ($\pu{mM}$) of a solution that is $\pu{20\%} \ce{H2SO4}$ by mass and that has a density of $\pu{1.198 g/L}$. For the answer, please provide two ...
1
vote
1answer
179 views

Finding mass percentage of components of a solid mixture

A workbook question asks: $\pu{2.184g}$ of a solid mixture containing only $\ce{K2CO3}$ ($\mathrm{FW = 138.2058}\pu{ g/mol}$) and $\ce{KHCO3}$ ($\mathrm{FW = 100.1154} \pu{g/mol}$) is dissolved in ...
-1
votes
1answer
220 views

Balancing the reaction of nitric acid with zinc using oxidation number method

In a previous question, there was confusion relating to what this "oxidation number method" is. So I will illustrate that before my question. Write the skeleton equation representing chemical ...
3
votes
2answers
826 views

What is the net ionic equation of the following?

Aqueous chlorine is added to a solution of aluminum bromide in a single replacement reaction which forms no precipitate and bromine liquid. Determine the net ionic equation. Since this is a single ...
2
votes
3answers
61 views

Copper Stoichometry Ratio Problem

I was given two equations as part of a problem into Copper Wiring production for planes: $$\ce{4CuFeS2 + 9 1/2 O2 + 4SiO2 \rightarrow Cu2S + Cu2O + 2SO2 + 4FeSiO3}$$ $$\ce{Cu2S + 2Cu2O \rightarrow ...
-1
votes
1answer
81 views

Balancing the intermolecular redox reaction

The redox reaction is: $\ce{SO2 + Na2CrO4 + H2SO4 -> Na2SO4 + Cr2(SO4)3 + H2O}$ This is what I tried(tho I got stuck at one point which is indeed the exact reason why I've asked this question): ...
2
votes
2answers
294 views

Does a stoichiometric coefficient represent molecules or moles of a substance?

I understand that the one mole of atoms is equal to $6.02\times10^{23}$ atoms. However, when I used various resources to learn about stoichiometry, they showed me a balanced equation: $$\ce{2H2O->...
1
vote
1answer
266 views

Concentration of excess reactant

If increasing/decreasing the concentration of an excess reactant influenced the percentage yield of a product experimentally, how could this be explained? I know that in theory, the excess shouldn't ...
4
votes
1answer
64 views

Is the kilogram still consistent with the old definition?

My old understanding was that a gram is the amount of mass in a cubic centimeter of water. But then I recently learned that the second was redefined to be some 9 billion cycles of a Caesium atom. ...
-4
votes
1answer
75 views

Stoicheometry questions: I've been having a bad time not understanding the questions and how the steps are to achieve the answer. please help [closed]

Cetyl palmitate (C32H64O2) is a waxy solid and is the main component of spermaceti, the once prized wax found in the skull of sperm wales. The heads of sperm whales can contain up to 1900 L of ...
-1
votes
1answer
1k views

Stoichiometric amounts

Can anyone inform me what the term stoichiometric amounts means. I know what stoichiometry means. It is the: The relationship between the relative quantities of substance taking part in a reaction ...
3
votes
1answer
108 views

Is it possible for me to derive Avogadro's number?

To my understanding the mole is the unit used to translate between mass on the atomic level and mass in the macro level, defined as the number of atoms in $12$ grams of Carbon-$12$, which apparently ...
-1
votes
1answer
53 views

Finding empirical formula [closed]

When determining the formula of a compound, why do we divide by the smallest number of moles once we already have calculated the number of moles for each element in order to find the empirical formua ...
1
vote
1answer
83 views

How did early chemists measure mass of atoms?

Here a book says that Berzelius measured atomic masses using a simple lab and his measurements was so close to modern results. Can someone explain how a person living in 19th century was able to ...
-1
votes
1answer
46 views

Is there a formula for density of any gaseous substance just based on its molar mass?

$\pu{112 ml}$ of hydrogen combines with $\pu{56 mL}$ of oxygen to form water. When $\pu{224 mL}$ of hydrogen is passed over heated cupric oxide, the cupric oxide loses $\pu{0.160 g}$ of its weight. ...
1
vote
1answer
144 views

Heat of Combustion

Methanol ($\ce{CH3OH}$) is regarded by many chemists as a possible liquid fuel for the future. The combustion of methanol occurs according to the equation: $$\ce{2CH3OH(g) + 3O2(g) -> 2CO2(g) +...
-2
votes
1answer
260 views

How to find the percentage composition of halogen using Carius method?

In the formula: $$\text{Percentage}=\frac{\text{atomic mass of halogen}}{\text{molecular mass of Agx}}\frac{\text{mass of AgX}}{\text{mass of compound}}\cdot100$$ here mass of compound is the mass ...
1
vote
0answers
49 views

Stoichiometry yielding negative volume

$15~ \textrm{mL}$ of $4 ~\textrm{N}$ hydrochloric acid, $ 25~ \textrm{mL}$ of $2~ \textrm{M}$ $\textrm{H}_3\textrm{PO}_3$ and a certain volume of $2.5~\textrm{M}$ sulphuric acid are mixed together and ...
1
vote
1answer
36 views

Why doesn't this question violate the conservation of mass?

Combustion of of $0.255 \space g$ of isopropyl alcohol produces $0.561 \space g$ of $\ce{CO_2}$ and $0.306 \space g$ of $\ce{H_2O}$. Determine the emperical formula of isopropyl alcohol. I'm not ...
-1
votes
2answers
1k views

KCl + CuCl2 in solution, is there a reaction?

I'm wondering if the reaction of $\ce{KCl + CuCl2}$ in solution (aq) will produce any products (have a net ionic equation/solid precipitate)? Using the metal activity series, I see that potassium is ...
1
vote
1answer
3k views

Balancing the reaction of potassium permanganate and sulfuric acid with hydrogen peroxide [duplicate]

A problem on redox reactions invites the reader to balance the actual reaction from which the redox simplification arose. After some hunting I found the balanced equation and attempted to re-derive ...
1
vote
1answer
44 views

Find amount of benzoic acid in dissolution

Solubility of benzoic acid in water at $\pu{0^\circ C}$ is $\pu{1.7 g/L}$ and given the fact that $\pu{37 mL}$ was used to dissolve $\pu{1 g}$ of benzoic acid. How much of the benzoic acid would be ...
3
votes
3answers
3k views

Is there always a limiting reagent in every equation?

Is there always a limiting reagent in every equation? For instance, is there a limiting reagent in $\ce{CaCl2 + Na2CO3 -> 2NaCl + CaCO3}$ where the same number of moles are reacting with each ...
5
votes
1answer
118 views

Mathematically balancing chemical equation yields weird results

I found this equation while testing my equation balancer: $$ \ce{a C7H6O3 + b C4H6O3 -> c C9H8O4 + d C2H4O2} $$ Obviously, $a = b = c = d = 1$ is a solution. However, if we were to bring in some ...
3
votes
2answers
1k views

What is the difference between ''1 C atom and 1 mole of C atoms?'' [closed]

Does 1 C atom mean 1 single C atom out of Avogadro's number of C atoms = 1 single C atom out of 6.023 X 10^23 numbers of C atoms? Does 1 mole of C atoms mean Avogadro's number of C atoms = 6.023 X 10^...
0
votes
1answer
187 views

What to say 'one mole of C atoms or one mole of C molecules?

What to say 'one mole of C atoms or one mole of C molecules in CO? Please point out if I am wrong here As we know, one molecule of CO = one mole of CO molecules = 6.223 X 10^23 number of CO molecules ...
-5
votes
1answer
535 views

What is the molecular formula of the hydrocarbon? [closed]

A hydrocarbon is burnt completely in excess oxygen to produce 0.04 mol of carbon dioxide and 0.72 g of water. What is the molecular formula of the hydrocarbon?
-1
votes
1answer
233 views

How to balance this manganese peroxide reaction with hydrogen peroxide? [duplicate]

I have the following equation, already written, with a few coefficients to write. $\ce{2MnO4^- + a H2O2 + b H+ -> 2Mn^2+ +c O2 + dH2O}$ I have put a = 1, b = 6, c = 3 and d = 4. The number of ...
0
votes
1answer
319 views

What is the volume of the produced SO2 gas at STP? [closed]

In a electricity producing plant $3.1\times10^7\ \mathrm{kg}$ coal with $2.4\ \%$ rhombic sulfur is burnt every year. What is the volume of the produced $\ce{SO2}$ gas at STP? My effort for solving ...
0
votes
1answer
87 views

Calculate the formula, and moles

If $\ce{1.84\times10^{-4}}$ moles of element A was completely reacted with element B to create $\ce{1.231\times 10^19}$ molecules of $\ce{(A3B2)_x}$ a hypothetical compound, what is the value of x? I ...
-1
votes
2answers
342 views

Molecular formula and decimal number

Today I did some stoichiometry exercise about finding the ratio between the elements. What confused me was that while the ratio was right, but it was decimal. Ex. Reducing $\pu{0.800 g}$ of lead ...
-2
votes
1answer
52 views

Where am I wrong in my calculations? [closed]

I am revisiting the concept of mole and I decided to figure out random values (for instance: mass of 1 molecule of water) to see how much I understand the concept of moles and how it relates to amu. ...
2
votes
2answers
856 views

How to find the molar mass of an iron compound based on its mass and mole fraction in the compound?

I'm trying to solve this question: We have a molecule composed of $3$ iron atoms, and $4$ atoms of another element. We are given the following information: it has $\pu{2.36 g}$ of iron for $\pu{3....
0
votes
1answer
124 views

Stoichiometry of incomplete combustion

Methane is burned with air in a continuous steady-state combustion reactor to yield a mixture of carbon monoxide, carbon dioxide and water. The feed to the reactor contains: $\pu{7.8 mole \% }\ce{...
2
votes
2answers
913 views

How can the number of moles in the product side be more than reactant?

A rigid stainless steel chamber contains $\pu{0.32 bar}$ of methane, $\ce{CH4}$, and excess oxygen $\ce{O2}$, at $\pu{200.0 °C}$. A spark is ignited inside the chamber, completely combusting the ...