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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2
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2answers
911 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 ...
9
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3answers
1k views

Unknown notation relating to stoichiometry

I have never seen the highlighted symbol before. What is the name of the symbol itself, and what does it mean in this context?
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2answers
125 views

Weight of sodium acetate required to get to certain pH

How many grams of $\ce{CH3COONa}$ we need to dissolve in $\pu{2.50 L}$ of water to get a solution with $\mathrm{pH} = 9.00$? Given $K_\mathrm{a}(\ce{CH3COOH}) = 1.75\cdot 10^{-5}$ Like solving a ...
2
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1answer
1k views

Mixing Ca(OH)2 with Ca(NO3)2

Mixing $\ce{Ca(OH)_2}$ with $\pu{0.1 M}$ concentration of $\ce{Ca(NO3)2}$. What will actually happen in the process? What I will see with my eyes? I know that $\ce{Ca^2+}$ cation with concentration ...
0
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1answer
315 views

Stoichiometry question

I tried solving the following question but am not sure I did so correctly and simply wished to verify it here. In 50.3 gr of a compound whose formula is $Na_2X_4O_7$ (where X is an unknown atom) are ...
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1answer
50 views

Can i calculate the solution of the problem in more simple way?

and i got a serious question. During my exercises at home, i found that im struggling a lot while solving simple problem`s like this one: I have an aquatic substance with 0.100 M of $\ce{Mg(NO3)2}$ ...
0
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1answer
249 views

Equivalent weight of the anhydrous acid [closed]

The cupric salt of a monobasic acid contains $3$ molecules of water of hydration per atom of $\ce{Cu}$. $\pu{1 g}$ of hydrated salt yielding on strong heating $\pu{0.3306 g}$ of $\ce{CuO}$. What is ...
0
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1answer
125 views

Mass of iron from the reduction of iron(III) oxide [closed]

Given the equation $$\ce{Fe2O3 + 3H2 -> 2Fe + 3H2O},$$ determine how many grams of $\ce{Fe}$ can be produced from $\pu{16.5 g}$ of $\ce{Fe2O3}$. I've already determined the masses of each ...
2
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1answer
143 views

Volume of nitrogen gas produced during taking off

The fuel in the buster rockets of the Space Shuttle is constituted of a mixture of ammonium perchlorate, $\ce{NH4ClO4}$, and aluminum powder. One of the reactions taking place during taking off is ...
6
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1answer
100 views

How much additional hydrochloric acid should be added to arrive at ‘excess acid’?

I am an IB student. And I am trying to find the mass percentage of $\ce{NaHCO3}$ in antacid. I am dissolving the antacid in $\pu{0.1 M}$ $\ce{HCl}$ solution. So, first of all I conducted some ...
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0answers
173 views

Validity of Law of Equivalence

Is law of equivalence valid for partial displacement reactions? 【I found this in my textbooks: According to the law of equivalence, whenever two substances react, the equivalents of one will be equal ...
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1answer
113 views

Is there a specific chemical reaction between capsaicin and casein? Is there a stoichiometric relationship between them? [closed]

I am trying to establish the reaction between capsaicin and casein in order to neutralize the effects of the capsaicin. Therefore, I must determine if there is a reaction and a stoichiometric relation....
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2answers
133 views

Neutralization of alkali solution by a mix of strong acids

$\pu{0.1 M}$ $\ce{HCl}$ and $\pu{0.2 M}$ $\ce{H2SO4}$ solutions are mixed in equal volume. This solution is diluted to double the volume. Find the volume of $\pu{0.1 M}$ $\ce{NaOH}$ which can be ...
-1
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1answer
54 views

What are the percentages of isotopes? [duplicate]

The average atomic mass of a sample of an element 'X' is 16.2u. What are the percentages of isotopes $\ce{^16_8X}$(atomic number = 8, atomic mass = 16) and $\ce{^18_8X}$(atomic number = 8, atomic ...
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1answer
93 views

Uncertainty in measuring the mass of the palm oil and the base in saponification

I am a student coming from the domain of mathematics, and I am working on error analysis and uncertainty, but I have a question in the domain of chemistry. I am studying the effect of the ...
-1
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1answer
1k views

Confusion in n-factor calculation

How do we calculate the equivalent weight of a compound, in a case where certain fraction of an element of the compound is getting reduced, while the other fraction is unaffected (no change in ...
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2answers
223 views

Calculation for buffer of pH 5 in sodium fluoride solution

From a journal: $\pu{500 mL}$ of $\pu{50 ppm}$ fluoride at $\mathrm{pH}~5$ was prepared by mixing $\pu{0.0552 g}$ of sodium fluoride with $\pu{4.1057 g}$ of sodium acetate and $\pu{1.65 mL}$ of ...
2
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0answers
88 views

Chain reaction vs single reaction

I am considering the following chain reaction: $$\begin{align} \ce{A_0 + B <=>[$N\cdot k_+$][$k_-$]A_1\\ A_1 + B <=>[$(N-1)\cdot k_+$][$2\cdot k_-$]A_2\\ A_2 + B <=>[$(N-2)\cdot k_+$]...
1
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1answer
753 views

Effective rate constants

I have the following reversible bimolecular reactions $$\begin{align} \ce{A_0 +B &<=>[$3k_+$][$k_-$] A_1} \\[5pt] \ce{A_1 +B &<=>[$2k_+$][$2k_-$] A_2} \\ \ce{A_2 +B &<=>[...
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1answer
2k views

Calculating n factor of SO2

I'm having a hard time trying to figure out n factor of $\ce{SO2}$ in the reaction $$\ce{FeS2 + O2 → Fe2O3 + SO2}\qquad \text{(unbalanced)}$$ To balance it, I saw that in 1 mole of $\ce{FeS2}$, it ...
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1answer
432 views

Concentration of ammonium phosphate if dissolved in water [closed]

If $\pu{2.54 mg}$ of ammonium phosphate is dissolved in enough water to make $\pu{300 mL}$ of the solution, what is the molar concentration of the solution? The answer is $\pu{5.68e-5 mol L-1}$. ...
1
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1answer
85 views

Concentration of mercury in body

Symptoms of mercury poisoning become apparent after a person has accumulated $\pu{20 mg}$ of mercury. If a person ingested $\pu{30 mg}$ of mercury, what concentration of mercury in parts per million, ...
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1answer
3k views

How do you write the ionization equation for calcium hydroxide?

This is a base that would ionize completely, and the dissociation equation would look like this: $$\ce{Ca(OH)2 <--> Ca^2+ + 2OH-}$$ but how would I write the Brønsted equation with water? $$\ce{...
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0answers
128 views

Using Avogadro's law to find gas volumes

An important step in the preparation of sulfuric acid involves the production of sulfur trioxide ($\ce{SO3}$) from sulfur dioxide ($\ce{SO2}$) and oxygen. $$\ce{2 SO2 (g) + O2 (g) -> 2 SO3 (g)}...
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0answers
47 views

Can I approximate the CO concentration of a combustion product, if I know the CO2 and O2 concentration?

Assume I have the product (exhaust gas) from a combusted air/petrol mix. The mixing ratio was richer than stoichiometric (i.e., air:fuel < 14.67 in this case), so there was no excess of oxygen. I ...
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1answer
35 views

Calculating percentage of use

In the following reaction, $\pu{14g}$ of $\ce{KClO3}$ produces $\pu{1.4g}$ of $\ce{KCl}$ $$\ce{2 KClO3 -> 2 KCl + O2}$$ What is the % of use? So first we balance the equation: $$\ce{2 KClO3 -&...
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0answers
24 views

Do we use volumes of both solutions if they have different densities to find cocentration of ions

So essentially lets say I am given a mixture of hexane, water and nickel chloride(masses also given) in a beaker, and am asked to find the concentration of the chloride ions in the aqueous layer of ...
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2answers
310 views

What's the best way to interconvert between molarity and percentage?

Let's say that I want to convert concentration of an acid from % to molarity. One way I found to do this is by using the following formula: percentage = (molarity * molar mass) / 10. Another way is ...
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1answer
389 views

What is the meaning of fractional coefficients in reaction equations? [duplicate]

There is a chemical reaction describing the oxidation of $\ce{Fe3O4}$ (magnetite) to $\ce{Fe2O3}$ (hematite). It is: $$\ce{2Fe3O4 (s) + 1/2 O2 (g) ->[\Delta] 3 Fe2O3 (s)}$$ My question is what ...
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0answers
216 views

Where to find good worksheets for balancing chemical equations

I am preparing for the Chemistry SAT in a couple of weeks. I am looking for worksheets like this that will give me practice balancing complex chemical equations with lots of compounds. Is there any ...
5
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1answer
693 views

Finding average Mr of a gaseous mixture

A 2 g mixture of cyclohexanol, acetone and pentanal is completely burnt in oxygen. When the gaseous product is passed through $\ce{P2O5}$, the mass of $\ce{P2O5}$ increased by 1.998 g. Find the ...
2
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0answers
130 views

Problem regarding failure of equivalence concept

Chile salt peter, a source of $\ce{NaNO3}$ also contains $\ce{NaIO3}$. The $\ce{NaIO3}$ can be used as a source of iodine, produced in the following reactions. \begin{align} \ce{IO3- + 3 HSO3- &...
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1answer
70 views

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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0answers
697 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
402 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
120 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
83 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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0answers
46 views

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 ...
15
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1answer
903 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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2answers
1k views

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 ...
3
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2answers
16k views

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^...
2
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1answer
67 views

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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2answers
586 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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1answer
424 views

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?
2
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1answer
142 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 ...
2
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1answer
8k 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 ...
0
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1answer
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 ...
3
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1answer
2k views

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 ...
0
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2answers
70 views

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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2answers
438 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 $\ce{NaClO4}$...