Answer:
130 mL
Explanation:
2FeCl3(aq) + 3K2S(aq) -----> Fe2S3(s) + 6KCl(aq)
Percent yield = actual yield/theoretical yield × 100
actual yield = 2.75 g
Theoretical yield = x
65= 2.75/x × 100
x= 2.75 × 100/65
x= 4.2 g
Number of moles of FeCl3 = mass/molar mass = 4.2 g/ 162.2 g/mol = 0.026 moles
Then;
n= CV
n= number of moles
C= concentration
V= volume
V= n/C
V= 0.026 moles/ 0.200 M
V= 0.13 L or 130 mL
Which best describes a swimming pool?
A.
It is a solute.
• B.
It IS
solvent.
C.
It is solution.
D.
It is a reactant.
•
E.
It is a product.
Answer:
Swimming pool is an example of solution
Explanation:
It has water (solvent) and dissolve ion (solute)
Answer:
it is a solution
Explanation:
the combining of (water and Cl and other pool chemicals) make it a solution.
The table shows four reactions.
Reactions
Reaction Equation
1 C3H8 + 5O₂ → 3CO₂ + 4H₂O
2 C₂H4 + H₂ → C₂H6
3 AgNO3 + NaCl - AgCl + NaNO3
4 2Fe + O₂ → 2Feo
Which of the above reactions is an example of combustion of an organic substance?
a) 1
b) 2
c) 3
d) 4
Answer:its B
Explanation:
i have done this before! and i got 100 so i hope you got all the other questions right!
The table shows four reactions. The reaction That is an example of combustion of an organic substance is C₂H₄ + H₂ → C₂H₆. The correct option is b) 2.
What are combustion reactions?Combustion reactions are those reactions in which the reactant reacts with oxygen and produces heat and light. An example is the burning of wood, it happens in the presence of oxygen.
Organic compounds are those compounds that are made by carbons. They are made by carbon-carbon or carbon-hydrogen bonds. They are naturally present in nature.
C₂H₄ + H₂ → C₂H₆
The equation above shows the reaction between methane and hydrogen, which is forming ethane in the presence of oxygen.
Thus, the correct option is b) 2. C₂H₄ + H₂ → C₂H₆.
To learn more about combustion reactions, refer to the link:
https://brainly.com/question/12172040
#SPJ5
How would an increased level of acetyl-CoA be expected to affect the pyruvate dehydrogenase reaction
Answer:
The pyruvate dehydrogenase kinase enzyme activity would increase, resulting in an inhibition of pyruvate dehydrogenase activity. ... An in vitro study shows that isocitrate dehydrogenase is activated in the citrate cycle.
Explanation:
A 80°C la presion de vapor del benceno (C6H6) es de 1 atm. Calcula la cantidad de hexano (C6H14) que debemos añadir a 200g de benceno para que su presion de vapor sea de 700mm de Hg
Answer:
18,9g de hexano son necesarios
Explanation:
Basados en la ley de Raoult, la presión de vapor ejercida por una solución es:
P = P°*Xsolvente
Donde P es la presión de la solución deseada = 700mmHg, P° la presión de vapor de vapor del benceno = 1atm = 760mmHg y X es la fracción molar del solvente (Benceno).
Reemplazando:
700mm Hg = 760mmHg * X(Benceno)
0.9211 = X(Benceno)
La fracción molar de benceno se define como:
X = Moles benceno / Moles benceno + Moles hexano
Moles benceno -Masa molar: 78g/mol-
200g * (1mol/78g) = 2.5641 moles benceno
X = Moles benceno / Moles benceno + Moles hexano
0.9211 = 2.5641 moles benceno / 2.5641 moles benceno + Moles hexano
0.9211moles Hexano + 2.3618 = 2.5641
0.9211*Moles Hexano = 0.2023
Moles hexano = 0.2023/0.9211 = 0.2196 moles hexano.
Masa Hexano -Masa molar: 86g/mol-
0.2196 moles hexano * (86g/mol) =
18,9g de hexano son necesariosLa cantidad de hexano (C6H14) que se debe agregar a 200 g de benceno para permitir que la presión de vapor se convierta en 700 mm de Hg sería:
18.9 g
Usando la ley de Raoult, la presión de vapor que libera una solución se encuentra por:
P = P ° × X disolvente
Donde (P) denota la presión de la solución deseada
P ° denota la presión de vapor del benceno y
X denota la fracción molar del disolvente (benceno).
En el caso dado,
(P) = 700 mmHg,
P° = 1atm = 760mmHg
Fracción molar de benceno = 0,9211 (∵ 700/760)
La fracción molar de benceno (X) = Moles de benceno/Moles de benceno + Moles de hexano
Moles de benceno - Masa molar: 78g / mol - 200 g × (1 mol / 78 g)
= 2.5641 moles de benceno
X = Moles de benceno/Moles de benceno + Moles de hexano
0.9211 = 2.5641 moles Benceno/2.5641 moles Benceno + Moles de Hexano
⇒ 0,9211 × moles de Hexano + 2,3618 = 2,5641
⇒ 0.9211 × moles de Hexano = 0.2023
∵ Moles de Hexano = 0.2023/0.9211
[tex]= 0.2196 moles[/tex]
[tex]Hexane mass - Molar mass = 86g/mol - 0.2196 mole hexane[/tex] × [tex](86g/mole)[/tex]
[tex]= 18.9g[/tex]
Por tanto, 18,9 g es la respuesta correcta.
Learn more about "Benzene" here:
brainly.com/question/25798187
3. How many moles are present in 100 g of Ca(NO3)2?
PLEASEEE HELP ASAPP
0Answer: 0.6094
Explanation:
no of moles = mass / molar mass = 100/164.088= 0.6094 mole
Answer:
0.609 moles
Explanation:
mass in g ÷ atomic mass = moles
Ca(NO₃)₂ = 1 Ca 40.078 amu
2 N 28.0134 amu
+ 6 O 95.994 amu
____________________
164.0854 amu
100 g ÷ 164.0854 amu = 0.609 moles
three significant digits
every action produces an equal and opposite -- ---------- when one object exterts a force on another object,the second object pushes back with the same amount of---------
someone knows the answer
Which has more mass, 2 kg of steel or 5 kg of feather.
Answer:
5 kg of feather
Explanation:
The field around a negatively charged object is symbolized by vectors pointing toward the sphere because a test charge, which is ______ by definition, would travel along such a vector if released in the field.
Positive
Negative
Answer:
Positive
Explanation:
Gallium has two natural occuring isotopes: Ga-69 with 68.9256 amu and a natural abundance of 60.11%, and Ga-71 with mass 70.9247 amu and a natural abundance of 39.8%. Calculate the atomic mass of gallium.
why are metal containers not used for storing acids
Metal containers are not used for storing acid because most of the time acid reacts with almost every metal and produces salts or oxides which alters the acid characteristics making it useless....
A solar energy company learns of several recent cyber-attacks targeting other companies in their industry and realizes they could be next. The company initiates an analysis to weigh the measures needed to counter the potential threat and minimizing the impact to their business in case those are exploited. Which security principle is illustrated in this example?
You burn a log on a fire. You use fire to warm yourself and help you see to read a book. What energy transformation is taking place?
Answer:
heat energy to keep you warm and light energy to be able to read your book
Explanation:
radical example ....
1. When a solution of an acid contains larger amount of acid, it is said to be
Answer:
highly concentrated solution of acid
Which expression is equal to f(x) · g(x)?
Answer:
C. x⁴ + 6·x³ - 12·x - 72
Explanation:
The given functions are;
[tex]f(x) =\sqrt{x^2 + 12 \cdot x + 36}[/tex]
g(x) = x³ -12
We have that [tex]f(x) =\sqrt{x^2 + 12 \cdot x + 36}[/tex] = [tex]f(x) =\sqrt{(x + 6)^2}[/tex] = (x + 6)
Therefore;
f(x)·g(x) = [tex]\sqrt{x^2 + 12 \cdot x + 36}[/tex] × (x³ - 12) = (x + 6) × (x³ - 12)
(x + 6) × (x³ - 12) = x⁴ - 12·x + 6·x³ - 72 = x⁴ + 6·x³ - 12·x - 72
∴ f(x)·g(x) = [tex]\sqrt{x^2 + 12 \cdot x + 36}[/tex] × (x³ - 12) = x⁴ + 6·x³ - 12·x - 72
Hi, in some texts number of water molecules released during polymerization is 2n but in others 2n-1 , why?
Answer:
Explanation:
Because you only have one repeat unit, n=1. 2n-1 becomes 2(1)-1 which is equal to one, meaning one molecule of H2O is produced, as is shown by the top condensation polymerisation reaction.
If you had two repeat units, n=2 so 2n-1=3. Three H2O molecules are produced because you would need two molecules of each reactant so three condesation reactions would occur and three molecules of H2O would be released.
how to make a sponge
Answer:
Synthetic sponges are made of three basic ingredients: cellulose derived from wood pulp, sodium sulphate, and hemp fiber. Other materials needed are chemical softeners, which break the cellulose down into the proper consistency, bleach, and dye.
Explanation:
IDK, BUT HOPE IT HELPS?
A television wave has a_____
wavelength than an infrared wave
Answer:
Longer
Explanation:
:)
Dominic needs some bleach to clean up a spill. He finds a bottle of cleaning solution, but there is no label on it. What should he do
Answer:
He should ask an adult if they know what the solution is. if they dont, put it back and find a different cleaning solution to use
an organic compound on analysis yielded 2.04g carbon, 0.34g hydrogen, 2.73g oxygen. calculate the empirical formula
Answer:
CH2O
Explanation:
According to this question:
C = 2.04g
H = 0.34g
O = 2.73g
First, we divide the mass value of each element by its atomic mass to convert to moles.
C = 2.04g ÷ 12 = 0.17mol
H = 0.34g ÷ 1 = 0.34mol
O = 2.73g ÷ 16 = 0.17mol
Next, we divide by the smallest mole value (0.17):
C = 0.17mol = 0.17 = 1
H = 0.34mol ÷ 0.17 = 2
O = 0.17mol ÷ 0.17 = 1
The whole number ratio of C,H,O is 1:2:1, hence, the empirical formula is CH2O.
What are the steps for writing the formula for a molecular compound? Naming a molecular
compound?
Answer:
Your question was explained in my chemistry book so I just shared the picture
Hope that helps
For the equilibrium
2H2S(g) ⇋ 2H2(g) + S2(g) Kc = 9 .0X 10-8 at 700°C
the initial concentrations of the three gases are 0.300 M H2S, 0.300 M H2, and 0. 1 50 M S2' Determine the equilibrium concentrations of the gases.
Answer:
Equilibrium concentrations of the gases are
[tex]H_2S=0.596M[/tex]
[tex]H_2=0.004 M[/tex]
[tex]S_2=0.002 M[/tex]
Explanation:
We are given that for the equilibrium
[tex]2H_2S\rightleftharpoons 2H_2(g)+S_2(g)[/tex]
[tex]k_c=9.0\times 10^{-8}[/tex]
Temperature, [tex]T=700^{\circ}C[/tex]
Initial concentration of
[tex]H_2S=0.30M[/tex]
[tex]H_2=0.30 M[/tex]
[tex]S_2=0.150 M[/tex]
We have to find the equilibrium concentration of gases.
After certain time
2x number of moles of reactant reduced and form product
Concentration of
[tex]H_2S=0.30+2x[/tex]
[tex]H_2=0.30-2x[/tex]
[tex]S_2=0.150-x[/tex]
At equilibrium
Equilibrium constant
[tex]K_c=\frac{product}{Reactant}=\frac{[H_2]^2[S_2]}{[H_2S]^2}[/tex]
Substitute the values
[tex]9\times 10^{-8}=\frac{(0.30-2x)^2(0.150-x)}{(0.30+2x)^2}[/tex]
[tex]9\times 10^{-8}=\frac{(0.30-2x)^2(0.150-x)}{(0.30+2x)^2}[/tex]
[tex]9\times 10^{-8}=\frac{(0.30-2x)^2(0.150-x)}{(0.30+2x)^2}[/tex]
By solving we get
[tex]x\approx 0.148[/tex]
Now, equilibrium concentration of gases
[tex]H_2S=0.30+2(0.148)=0.596M[/tex]
[tex]H_2=0.30-2(0.148)=0.004 M[/tex]
[tex]S_2=0.150-0.148=0.002 M[/tex]
What are the prefixes for molecular compounds?
Answer:
In nomenclature of simple molecular compounds, the more electropositive atom is written first and the more electronegative element is written last with an -ide suffix.
The Greek prefixes are used to dictate the number of a given element present in a molecular compound.
Prefixes can be shortened when the ending vowel of the prefix “conflicts” with a starting vowel in the compound.
Common exceptions exist for naming molecular compounds, where trivial or common names are used instead of systematic names, such as ammonia (NH3) instead of nitrogen trihydride or water (H2O) instead of dihydrogen monooxide.
Terms
nomenclatureA set of rules used for forming the names or terms in a particular field of arts or sciences.
electronegativeTending to attract electrons within a chemical bond.
electropositiveTending to not attract electrons (repel) within a chemical bond.
Chemical Nomenclature
The primary function of chemical nomenclature is to ensure that a spoken or written chemical name leaves no ambiguity concerning to what chemical compound the name refers. Each chemical name should refer to a single substance. Today, scientists often refer to chemicals by their common names: for example, water is not often called dihydrogen oxide. However, it is important to be able to recognize and name all chemicals in a standardized way. The most widely accepted format for nomenclature has been established by IUPAC.
Molecular compounds are made when two or more elements share electrons in a covalent bond to connect the elements. Typically, non-metals tend to share electrons, make covalent bonds, and thus, form molecular compounds.
Rules for Naming Molecular Compounds:
Remove the ending of the second element, and add “ide” just like in ionic compounds.
When naming molecular compounds prefixes are used to dictate the number of a given element present in the compound. ” mono-” indicates one, “di-” indicates two, “tri-” is three, “tetra-” is four, “penta-” is five, and “hexa-” is six, “hepta-” is seven, “octo-” is eight, “nona-” is nine, and “deca” is ten.
If there is only one of the first element, you can drop the prefix. For example, CO is carbon monoxide, not monocarbon monoxide.
If there are two vowels in a row that sound the same once the prefix is added (they “conflict”), the extra vowel on the end of the prefix is removed. For example, one oxygen would be monooxide, but instead it’s monoxide. The extra o is dropped.
Generally, the more electropositive atom is written first, followed by the more electronegative atom with an appropriate suffix. For example, H2O (water) can be called dihydrogen monoxide (though it’s not usually). Organic molecules (molecules made of C and H along with other elements) do not follow this rule.
Here are the prefixes in naming molecular compounds:
Mono- 1
Di- 2
Tri- 3
Tetra- 4
Penta- 5
Hexa- 6
Hepta- 7
Octa- 8
Nona- 9
Deca- 10
Molecular compounds are named using a systematic approach of prefixes to indicate the number of each element present in the compound.
I hope it helps ●~●
#CarryOnLearningBalance the equation of. _C + _O2 -- _CO
Explanation:
2C +O2 = 2CO
this will be the answer
Suppose that you chose sodium carbonate to precipitate the chromium ions from a solution of chromium (III) chloride. Write and balance the equation of this double-displacement reaction.
If the solution has a volume of 520 mL and the concentration of chromium (III) chloride is 0.224 M, how many grams of sodium carbonate should you add to the solution to precipitate out all the chromium ions?
Answer:
18.5g Na2CO3
Explanation:
Chromium (III) chloride, CrCl3, reacts with Na2CO3 as follows:
2CrCl3 + 3Na2CO3 → Cr2(CO3)3(s) + 6NaCl
Where 2 moles of CrCl3 react with 3 moles of Na2CO3 to produce 1 mole of Cr2(CO3)3 -The precipitate-
To solve this question we need to find the moles of CrCl3 added. With the chemical equation we can find the moles of Na2CO3 and its mass as follows:
Moles CrCl3:
520mL = 0.520L * (0.224mol/L) = 0.116 moles CrCl3
Moles Na2CO3:
0.116 moles CrCl3 * (3 mol Na2CO3 / 2mol CrCl3) = 0.175 moles Na2CO3
Mass Na2CO3 -Molar mass: 105.99g/mol-
0.175 moles Na2CO3 * (105.99g/mol) = 18.5g Na2CO3
heyy guys, so basically i need help with stoichiometric calculation I will give you 100 points just to answer all of these answers accurately with working out (ps ill mark you brainliest x), thanks. PLEASE HELPPP. I'm desperate x
3. What masses of ethanol and ethanoic acid would need to be reacted together to give 1 g of ethyl ethanoate?
C^2H^5OH + CH^3CO^2 H → CH^3CO^2C^2H^5 + H^2O
4. What mass of iron(III) oxide would need to be reduced to produce 100 tonnes of iron in a blast furnace?
Fe^2^O^3 + CO → Fe + CO^2
5. What mass of silver nitrate as a solution in water would need to be added to 5 g of sodium chloride to
ensure complete precipitation of the chloride?
AgNO^3(aq) + NaCl (aq) → AgCl (s) + NaNO^3(aq)
6. Copper(II) oxide reacts with sulphuric acid to produce copper(II) sulphate. If this is allowed to crystallise the formula of the crystals is CuSO 4 .5H 2 O. What mass of copper oxide would be needed to produce 100 g of crystals?
CuO + H^2O + H^2SO^4 = CuSO^4 .5H^2O
7. In the following reactions calculate the mass of precipitate formed from 20 g of the metal salt in each case.
a. ZnSO^4 (aq) + 2NaOH → Zn(OH)^2(s) + Na^2SO^4(aq)
b. Al^2 (SO^4 ) 3(aq) + 6NaOH → 2Al(OH)^3(s) + 3Na^2SO^4(aq)
c. MgSO^4(aq) + 2NaOH → Mg(OH)^2(s) + Na^2^SO^4(aq)
Answer:
3. The mass of ethanol required is approximately 0.522869 g
The mass of ethanoic acid required is approximately 0.68156 g
4. The mass of iron (III) oxide required is approximately 285.952.189.095 tonnes
5. The mass of silver nitrate required is approximately 14.53 grams
6. The mass of copper oxide that would be needed is approximately 31.86 grams
7. a. The mass of the precipitate, Zn(OH)₂ formed is approximately 49.712 grams
b. The mass of the precipitate, Al(OH)₃ formed is approximately 13 grams
c. The mass of the precipitate, Mg(OH)₂, formed is approximately 14.579925 grams
Explanation:
3. The 1 mole of ethanol and 1 mole of ethanoic acid combines to form 1 mole of ethyl ethanoate
The number of moles of ethyl ethanoate in 1 gram of ethyl ethanoate, n = 1 g/(88.11 g/mol) = 1/88.11 moles
∴ The number of moles of ethanol = 1/88.11 moles
The number of moles of ethanoic acid = 1/88.11 moles
The mass of ethanol = (46.07 g/mol) × 1/88.11 moles = 0.522869 g
The mass of ethanoic acid in the reaction = 60.052 g/mol × 1/88.11 moles ≈ 0.68156 g
4. 1 mole of iron(III) oxide reacts with 1 mole of CO₂ to produce 1 mole of iron
The number of moles in 100 tonnes of iron= 100000000/55.845 = 1790670.60614 moles
The mass of iron (III) oxide required = 159.69 × 1790670.60614 = 285952189.095 g ≈ 285.952.189.095 tonnes
5. The number of moles of NaCl in 5 grams of NaCl = 5 g/58.44 g/mol = 0.0855578371 moles
The mass of silver nitrate required, m = 169.87 g/mol × 0.0855578371 moles ≈ 14.53 grams
6. The number of moles of CuSO₄·5H₂O in 100 g of CuSO₄·5H₂O = 100 g/(249.69 g/mol) ≈ 0.4005 moles
The mass of copper oxide required, m = 79.545 g/mol × 0.4005 moles ≈ 31.86 grams
7. a. The number of moles of NaOH in the reaction = 20 g/(39.997 g/mol) ≈ 0.5 moles
2 moles of NaOH produces 1 mole of Zn(OH)₂
0.5 moles of NaOH will produce 0.5 mole of Zn(OH)₂
The mass of 0.5 mole of Zn(OH)₂ = 0.5 mole × 99.424 g/mol = 49.712 grams
The mass of the precipitate, Zn(OH)₂ formed = 49.712 grams
b. 6 moles of NaOH produces 2 moles Al(OH)₃
20 g, or 0.5 mole of NaOH will produce (1/6) mole of Al(OH)₃
The mass of the precipitate, Al(OH)₃ formed, m = 78 g/mol×(1/6) moles = 13 grams
c. 2 moles of NaOH produces 1 mole of Mg(OH)₂, therefore;
20 g or 0.5 moles of NaOH formed (1/4) mole of Mg(OH)₂
The mass of the precipitate, Mg(OH)₂, formed, m = 58.3197 g/mol × (1/4) moles = 14.579925 grams
Answer:
Explanation:
i will show in details how 2 do the 1st Q n u can do the rest by following the way how it is done
3. given C^2H^5OH + CH^3CO^2H → CH^3CO^2C^2H^5 + H^2O
molar ratio of ethanol, ethanoic acid and ethyl ethanoate is 1 : 1 : 1
so mass = no. of moles * molecular mass
for same no. of moles, mass / molecular mass is the same
molecular mass of CH^3CO^2C^2H^5 = 12+1*3+12+16*2+12*2+5*1 = 88
molecular mass of C^2H^5OH = 12*2+1*5+16+1 = 46
molecular mass of CH^3CO^2H = 12+1*3+12+16*2+1 = 60
1 g of ethyl ethanoate = 1/88 mole
it requires 1/88*46 = 0.5227 g of ethanol; and
1/88*60 = 0.6818 g of ethanoic acid
to react together to form 1 g of ethyl ethanoate
Cuál o cuáles de las siguientes características son correctas para la mayoría de los compuestos del carbono?
I) Los compuestos del carbono son solubles en disolventes no polares como el hexano, benceno, éter, etc.
II) Los compuestos del carbono generalmente presentan puntos de fusión y de ebullición bajos
III) La gran mayoría de los compuestos del carbono son combustibles, sean estos, gaseosos, líquidos o sólidos
IV) El enlace covalente es característico de los compuestos del carbono
Todas son correctas
II
I y IV
I, III y IV
Answer:
Todas son correctas
Explanation:
I) Los compuestos del carbono son solubles en disolventes no polares como el hexano, benceno, éter, etc. VERDADERO. La mayoría de los compuestos de carbono son apolares, y basados en la regla: Similar disuelve similar, podemos presumir que la mayoría de compuestos de carbono se disuelven en solventes no polares.
II) Los compuestos del carbono generalmente presentan puntos de fusión y de ebullición bajos. VERDADERO. Al ser sustancias apolares, sus fuerzas electrostáticas son bajas. De la misma manera, como su masa atómica es pequeña, las fuerzas de Van der Waals son despreciables haciendo que sus puntos de fusión y ebullición sean bajos respecto a sustancias de estrucutra similar.
III) La gran mayoría de los compuestos del carbono son combustibles, sean estos, gaseosos, líquidos o sólidos. VERDADERO. Los gases (Como el gas natural) son combustibles usados para cocina. Los líquidos (Como la gasolina) son combustibles y bastante inflamables. Los sólidos (Como la madera) se usan como combustibles para hacer asados o son el combustible en incendios forestales.
IV) El enlace covalente es característico de los compuestos del carbono. VERDADERO. La polaridad del carbono es neutral haciendo que la mayoría de los enlaces que forma sean covalentes.
Todas son correctas
Explain how carbon’s bonding ability makes it unique.
[tex]\huge\fcolorbox{red}{pink}{Answer ♥}[/tex]
The carbon atom is unique among elements in its tendency to form extensive networks of covalent bonds not only with other elements but also with itself. ... Moreover, of all the elements in the second row, carbon has the maximum number of outer shell electrons (four) capable of forming covalent bonds.
Hope it helps uh ✌️✌️✌️
Gud mrng
Put these atoms in order from most negative overall charge to least negative
overall charge.
11 Atom X: 104 protons, 102 electrons
11 Atom B: 24 protons, 18 electrons
1 Atom Q: 15 protons, 16 electrons
11. Atom P: 7 protons, 10 electrons
Answer:
3 Protons, 2 Neutrons, & 3 Electrons. Is the charge of this atom positive, negative, or neutral?
Explanation:
Put these atoms in order from most negative overall charge to least negative
overall charge.
11 Atom X: 104 protons, 102 electrons
11 Atom B: 24 protons, 18 electrons
1 Atom Q: 15 protons, 16 electrons
11. Atom P: 7 protons, 10 electrons
9. Explain why you can't write the formula of the ionic compound that forms between Fe
and S?
Answer:
See explanation
Explanation:
According to Fajan's rules, the degree of covalent character of a bond depends on the relative polarizing power of ions.
Generally, ions become more polarizing when they are small and highly charged. Large negative ions are more polarizable than small ones.
A very small positive charge concentrated on a small area such as in Fe^2+ makes the ion highly polarizing. Also, a large negative ion such as S^2- is highly polarizable.
As a result of these FeS has considerable covalent character hence we can not simply write the formula of the ionic compound that forms between Fe and S?
