Chemistry, 05.11.2019 01:31, leahstubbs

Consider the following reaction:
fe3+(aq)+scn−(aq)⇌fescn2+(aq)
a solution is made containing an initial [fe3+] of 1.1×10−3 m and an initial [scn−] of 8.2×10−4 m. at equilibrium, [fescn2+]= 1.8×10−4 m .
calculate the value of the equilibrium constant (kc).
express your answer using two significant figures.

Answers: 3

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answered: plum65

Kc = 3.1x10²

Explanation:

At equilibrium, the velocity of product formation is equal to the velocity of reactants formation. For a generic reaction, the equilibrium constant (Kc) is:

aA + bB ⇄ cC + dD

$Kc = \frac{[C]^c*[D]^d}{[A]^a*[B]^b}$

Where [X] is the molar concentration of X, and the solid substances are not considered (because it's activity is 1, for the other substances, the activity is substituted for the molar concentration, which forms the equation above).

For the reaction given, let's make an equilibrium chart:

Fe³⁺(aq) + SCN⁻(aq) ⇄ FeSCN²⁺(aq)

1.1*10⁻³ 8.2*10⁻⁴ 0 Initial

-x -x +x Reacts (stoichiometry is 1:1:1)

1.1*10⁻³ -x 8.2*10⁻⁴ -x x Equilibrium

x = 1.8*10⁻⁴ M, so the molar concentrations at equilibrium are:

[Fe⁺³] = 1.1*10⁻³ - 1.8*10⁻⁴ = 9.2*10⁻⁴ M

[SCN⁻] = 8.2*10⁻⁴ - 1.8*10⁻⁴ = 6.4*10⁻⁴ M

[FeSCN⁺²] = 1.8*10⁻⁴ M

Kc = [FeSCN⁺²]/([Fe⁺³]*[SCN⁻])

Kc = (1.8*10⁻⁴)/(9.2*10⁻⁴*6.4*10⁻⁴)

Kc = 306 = 3.1x10²

answered: Guest

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is $1s^{2}2s^{2}2p^{6}3s^{1}$ and electronic configuration of phosphorous is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$ .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

$3na + p \rightarrow na_{3}p$

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.