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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Factors Affecting Rates of Reaction [closed]

1-Bromopropane reacts with sodium hydroxide solution to give propan-1-ol. The hydroxide ions replace the bromine in the organic molecule: $$\ce{CH3CH2CH2Br + OH- -> CH3CH2CH2OH + Br-}$$ This is a ...
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Writing a chemical equation with a reactant of unspecified chain length [closed]

Would appreciate it if I got some general tips and hints and not the solution cause I'm trying to learn from this question :) The question is as follows: FA1 is a solution containing $\pu{5.00 g dm-3}...
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Converting w/v to mole fraction

If I have 10 mL 0.9% w/v $\ce{NaCl}$ solution, I can deduce that the solution contains 0.09 g of $\ce{NaCl}$. Imagine that this is standard laboratory conditions and 1 ml = 1 g is acceptable. Is the ...
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Help with two containers problem, Xenon

In two containers we have Xenon. The volume of the first container is 2780 L, temperature is 300 degree Celsius, and n = 200 mol. Volume of the second container is 4000 L, temperature is 1300 degrees ...
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Is this stoichiometric question answerable? (unknown variable)

This question kind of borders on the fields of both semantics and math, as well as chemistry, but I still believe this is the right place to ask. On a test I took, a question was posed as such: Via ...
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Calculating change in Gibbs Free Energy for a specific type of problem

Can anyone describe what is going on here? $$Si(liq.)=Si_{(1 weight percentFe)}$$ I have come across this statement quite a few times in Metallurgical Thermodynamics.All that they ask for is change in ...
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Filling up a table about a chemical reaction

I am filling up this table but I'm not sure about what it means in the mass row, amount of substance, molecule quantity. In mass do I just have to repeat 16 in the second column or do I need to put ...
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When multiple sources give the content of an ingredient my an unqualified percentage, can I safely assume this is by weight? Or; it's not a wart

I am trying to make a simple scented shampoo and body soap for my own use and for Christmas gifts. I statr with a base of 32 oz – (a bit under a kg) of a mild commercial castille soap (Dr. Bronner’s ...
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Find the molecular formula of a gas

The problem is: A quantity of $\pu{35.2 g}$ if a certain hydrocarbon gas, occupies $\pu{13.2 L}$, measured at $\pu{1 atm}$ and at $\pu{323 K}$. Knowing that 85.5% of is C, find the molecular formula ...
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Molarity of a mix between solid and solution

$\pu{50 g}$ of solid $\ce{NaOH}$ is added to $\pu{1.5 L}$ of $\pu{2.4 M}$ $\ce{NaOH}.$ Water is then added to the mix until the solution reaches $\pu{5 L}.$ I need to find molarity of the final ...
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45 views

When blue vitriol is dissolved in water [closed]

when CuSO4.5H2O is dissolved in water, what physical and chemical effects happens to its water of crystallization? While solving a stoichiometric problem the ques was that 1litre of CuSO4.5H2O was ...
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60 views

Is this calculation of the amount of required hydrogen gas correct?

I was a bit hesitant to post this question for it may appear like a "homework help" type of question. But upon rethinking it felt like a genuine question. I was studying stoichiometry with ...
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Why does the Avogadro's number have the unit of reciprocal mole? [closed]

In my understanding, $$1 \ mol \equiv N_A \ (atoms)$$ (Don't say it might not be atoms but molecules and also don't say what's it's not even a unit) Then the unit should be $N_A = 1 \ mol/atoms = 1 \ ...
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What does the term 'by mass' mean with respect to different contexts?

I've seen the term 'by mass' being used in various sorts of contexts. Some, while explaining the law of definite proportions say, the 'same proportions by mass', some say 'constant chemical ...
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Combustion of methane and ethane

I'm having trouble with the following problem: A gas fuel of Methane ($\ce{CH4}$) and Ethane ($\ce{C2H6}$) is burned with atmospheric air, and the volumetric analysis of the products of combustion ...
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56 views

Finding the equivalent weights of the oxide and the metal when reduced by hydrogen [closed]

A metal oxide ($\pu{1.80 g}$) required $\pu{833 ml}$ of hydrogen at NTP to be reduced to its metal. What are the equivalent weights of the oxide and the metal? My attempt: $$\text{equivalent of metal ...
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How much grams oxygen is in 7 gram magnesiumnitrate? Mg(NO3)2 [closed]

I calculated this: molar mass (M) of Mg(NO3)2 is 148,32 (24,3 + 214,01 + 616) so when there is 7 grams Mg(NO3)2 there is 0,0472 mol (7/148,32) But how do i find out how much of that is oxygen? Do i ...
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87 views

What does the equilibrium constant mean for reactions with very small concentrations?

When you calculate the equilibrium constant for a reaction with a higher concentration of reactants, the answer is fairly intuitive. For example, for the reaction: $$\ce{A + B <=> C}$$ Where we ...
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Balancing a reaction where dichromate ion reacts with ethanol to give Cr(III) and carbon dioxide

I have only started to learn balancing redox reactions, and a recent question has me confused. The question is : Balance in both acidic medium and basic medium: $$\ce{Cr2O7^2- + C2H5OH -> Cr^3+ + ...
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Question about null space balancing method

I'm trying to use the null space method to balance the following equation: . I obtained the following composition matrix: $$\begin{bmatrix} 3 & 8 & 1 & 12 & 4 & 2 \\ 1 & 0 &...
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Finding the volume of carbon dioxide needed in formation of calcium carbonate

Carbon dioxide was bubbled into limewater (a solution of calcium hydroxide) and the solid calcium carbonate precipitated was filtered off, dried and weighed. If $\pu{0.50 g}$ of calcium carbonate were ...
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What is the liquid which has the most hydrogen atoms per volume?

What is the liquid which has the most hydrogen atoms per volume at STP ? Is there anything better than water? This answer does not answer this question because none of the compounds listed in it are ...
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Number of moles of acidified potassium dichromate required to liberate 6 moles of iodine from an aqueous solution of iodate ions

I came across this question in a recent exam I had taken: How many moles of acidified $\ce{K2Cr2O7}$ is required to liberate 6 moles of $\ce{I2}$ from an aqueous solution of $\ce{I-}$ ? So this is ...
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Stoichiometric calculation of composition of a compound

I have a question from a high school review package. I don't need the answer, but one thing that is bugging me is that, I feel as if I do not understand the question at all. I don't know what it wants ...
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109 views

Calculation of pH in acid base reaction

This problem(from ionic equiibrium) states: We are given $\pu{40 mL}$ of $\pu{0.1 M}$ $\ce{HCl}$ and $\pu{10 mL}$ of $\pu{0.45 M}$ $\ce{NaOH}$ in two separate beakers. These two solutions are mixed. ...
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Dissolution of iron(III) hydroxide

Problem From the theoretical tour of the Mendeleev Olympiad in Chemistry: a) Calculate the minimal amount of sulfuric acid that should be diluted with water to yield $\pu{100 mL}$ of solution that ...
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Why use 1.008 g/mol instead of 1.0079 g/mol calculating the number of moles in 75.0 g H_2 molecules? [closed]

Why are figures removed from the calculation for values that are known in more detail? E.g. if you want to calculate the number of moles in 75.0 g H2 molecules. Why should one here use for the ...
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Stoichiometry and percentage concentration [closed]

10 g of Mg(NO3)2 was dissolved in 120 g of water. The result is a solution with a density of 1.12 g / ml. Determine the percentage concentration (in %) and the molar concentration (in mol/L) of the ...
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67 views

How many kilograms of graphite are consumed while producing 4 kg of Al through Hall-Heroult process?

How many kilograms of graphite are consumed while producing 4 kg of $\ce{Al}$ through Hall-Heroult process? This looks like a simple stoichiometry problem: $$\ce{4Al^3+ + 12e- -> 4Al} \; \; \; \; \...
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Can the Belousov-Zhabotinsky reaction be simulated with the Brusselator?

I'm trying to simulate the Belousov-Zhabotinsky reaction mathematically, with a system of ODEs. I know how to do this with the Oregonator and now I'm looking for another model to simulate the BZ-...
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Does the property of additivity for the amounts of different substances hold up for ideal gas law?

A mixture contains $\pu{8.00 g}$ each of $\ce{O2},$ $\ce{CO2},$ and $\ce{SO2}$ at STP. Calculate the volume of this mixture. Which of the gases would exert the greatest pressure and why? Here is my ...
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Determining amount (in mols) of oxygen needed to fully combust coal

I'm trying to calculate the amount of oxygen needed to fully combust some coal. As an example, assume I have $\pu{1 kg}$ of coal which is, by mass fraction, 60% carbon ($\ce{C}$) 40% hydrogen ($\ce{...
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38 views

How to solve this dimensional analysis/stoichometry problem

This problem has been giving me a headache for the last hour on my homework. Does anyone have any pointers in the right direction? Finally, on January 28th, 2014, in Germany, a barn containing 90 ...
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Strong Base and weak acid reaction problem

I got the above problem correct by setting up the net ionic equation and finding the limiting reactant. I found that there were 0.01076 moles of NaOH left, and then calculated it's molarity which led ...
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Net production of CO2 in plants

I am trying to understand in a qualitative way photosynthesis. I am not a chemist so please have some patience. I read on the Wikipedia page for photosynthesis that the way plants use $\ce{CO2}$ is ...
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How to calculate “volume of gas” generated by a given ion ore in a blast furnace? [closed]

A blast furnace makes pig iron containing $3.6\% \; \ce{C}$, $1.4\% \; \ce{Si}$, and $95\% \; \ce{Fe}$. The ore is $80\% \; \ce{Fe2O3}$, $12\% \; \ce{SiO2}$, and $\ce{Al2O3}$. The blast furnace gas ...
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how much baking soda and vinegar will you need to fully fill a ziplock bag up without popping it? [closed]

EXACTLY how much baking soda and vinegar will you need to FULLY fill a ziplock bag up without popping it or it being deflated? I am really confused. That is all our teacher told us and he said that ...
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How to model the Belousov-Zhabotinsky (BZ) (in Maple) [closed]

I need to model the Belousov-Zhabotinsky reaction (or a different oscillating one). I found out about the Oregonator and the Brusselator reaction and now I want to model them in Maple (or similar ...
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241 views

How many significant figures should I report calculating volume concentrations? [closed]

Let's say a $\pu{300mL}$ solution of $\ce{CuCl_2}$ was diluted to $\pu{900mL}$. I am then asked to calculate the concentration of the new solution. My solution to the problem is as follows: $$\begin{...
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What is the precipitate of aqueous copper (II) and polysulfides?

So if you heat up a piece of sodium engulfed in a large excess of sulfur, what you would get (from what I've read) is sodium polysulfide $\ce{NaS_n}$. But how large can $n$ get? If you left sodium ...
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249 views

Preparation of potassium cyanide from potassium ferrocyanide via HCN

Does anyone have any experience with the preparation of potassium cyanide from potassium ferrocyanide via $\ce{HCN}$ method? I did some math and am going to proceed eventually, any advice would be ...
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Question on chemical equilibrium [closed]

8 moles of so2 and 4 moles of O2 are mixed in a closed vessel.the reaction proceeds at constant temperature. By the moment when equilibrium sets in,80% of the initial amount of so2 enters into the ...
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898 views

Can someone help me find the limting reagent? [closed]

Okay, so for home work i was given this problem. Suppose that 8.00g of CH4 reacts with 16.00g O2 to form CO2 and H2O, find the grams of CH4, H2o, and O2 left over Balanced Equation : CH4 + 2O2 = ...
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1answer
68 views

How to deal with the unit “Coulomb per equivalent”? [duplicate]

In a question that I came across they defined $1\,\pu{F}$ as 96500 coulomb per equivalent. Now as far as my knowledge is concerned $1\,\pu{F} = 96500\,\pu{C/mol}$. The question involved asks to ...
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If 40.0 grams of Aluminum and 25.0 gram of Cl2 reacted together how much AlCl3 can be produced? [closed]

The equation goes as follows: Al + Cl2 ----> AlCl3. The equation is unbalanced so I then balanced the equation. Heres what I did: 2Al + 3Cl2 ---> 2AlCl3 I then got the Molar mass of 40 g of Aluminum....
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Why Molecular Solids can be treated as Monoatomic in Reactions

I'm trying to figure out what is the precise rule for the formula of elemental substances in reactions. I'm afraid I can't word the question properly, so I'll try to give some examples. 1)Oxidation ...
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1answer
195 views

What did Richter mean regarding an acid base reaction?

Recently I've been reviewing concepts belonging to the history of chemistry. But I came stuck at trying to understand a passage which I read from wikipedia entry (and which it seems has been mentioned ...
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91 views

Indicators of Cu(I) or Cu(II)

We performed an experiment in class where we placed a piece of copper wire in a solution of silver nitrate, we were tasked with predicted the mass of copper that should react and the mass of silver ...
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What will be the number of molecules per mole in a set of different gases when compared with hydrogen? [closed]

The source of my question is due the nature of a problem which I found misleading in the way how it was presented. The problem is as follows: The molecular weight of hydrogen ($\ce{H2}$), helium ($...
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1answer
67 views

Determining sulfate content in Mohr's salt

I am practicing problems for my chemistry test and I am stuck on the following problem: The value of $x$ in $\ce{Fe(NH4)2(SO4)2 ⋅ xH2O}$ can be found by determining the amount, in moles, of sulfate ...

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