Cov Lus Nug Piv Txwv Sib Tham Txog Kev Sib Npaug Tshuaj
Kev sib npaug ntawm cov tshuaj lom neeg yog ib lub tswv yim tseem ceeb hauv chemistry uas piav qhia txog lub xeev uas cov nqi ntawm cov tshuaj tiv thaiv pem hauv ntej thiab rov qab hauv cov tshuaj tiv thaiv yog sib npaug. Hauv qab qhov xwm txheej no, qhov concentration ntawm cov reactants thiab cov khoom tseem nyob ruaj khov. Tsab xov xwm no yuav muab ntau qhov piv txwv ntawm cov teeb meem thiab lawv cov kev daws teeb meem los pab nkag siab txog lub tswv yim ntawm kev sib npaug ntawm cov tshuaj lom neeg.
Cov Ntsiab Lus Tseem Ceeb ntawm Kev Sib Npaug Tshuaj
Kev sib npaug ntawm cov tshuaj lom neeg tshwm sim thaum cov tshuaj lom neeg tuaj yeem ua rov qab los yog ob qho tib si. Kev ua rov qab tuaj yeem ua cim raws li hauv qab no:
\[ \text{aA} + \text{bB} \rightleftharpoons \text{cC} + \text{dD} \]
Qhov twg:
- A thiab B yog cov tshuaj reactants,
- C thiab D yog cov khoom,
- a, b, c, thiab d yog cov coefficients stoichiometric ntawm txhua yam khoom.
Thaum mus txog qhov sib npaug, qhov nrawm ntawm qhov kev tshuaj tiv thaiv pem hauv ntej (tsim cov khoom) yog sib npaug rau qhov nrawm ntawm qhov kev tshuaj tiv thaiv rov qab (tsim cov tshuaj reactants). Ntawm lub sijhawm no, txawm hais tias qhov kev tshuaj tiv thaiv txuas ntxiv mus tas li, qhov concentration ntawm txhua yam khoom tseem tsis hloov pauv.
Kev Sib Npaug Tsis Tu Ncua (K)
Qhov sib npaug tas mus li \(K_c\) rau cov tshuaj tiv thaiv saum toj no tuaj yeem qhia tau tias:
\[ K_c = \frac{{[\text{C}]^c [\text{D}]^d}}{{[\text{A}]^a [\text{B}]^b}} \]
Qhov twg [X] yog qhov concentration ntawm cov tshuaj X. Thaum siv cov siab ib nrab hauv qhov sib npaug ntawm cov roj, qhov sib npaug tas li yog qhia ua \(K_p\).
Cov Lus Nug Piv Txwv Txog Kev Sib Npaug Tshuaj
Lo lus nug 1: Cov tshuaj tiv thaiv nrog cov ntaub ntawv concentration
Muab 1 mole ntawm N₂ thiab 3 mole ntawm H₂ tso rau hauv lub thawv 1-liter ntawm qhov kub thiab txias. Cov tshuaj tiv thaiv ua raws li nram no:
\[ \text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) \]
Tom qab mus txog qhov sib npaug, pom 0,8 mol ntawm N₂. Xam qhov sib npaug tas mus li \(K_c\).
Kev Sib Tham:
1. Txheeb xyuas qhov kev hloov pauv ntawm qhov concentration:
Thaum pib, tus naj npawb ntawm moles yog:
– \([\text{N}_2]_{initial} = 1 \, \text{mol/L}\]
– \([\text{H}_2]_{initial} = 3 \, \text{mol/L}\]
– \([\text{NH}_3]_{initial} = 0 \, \text{mol/L}\]
Thaum sib npaug, tus naj npawb ntawm moles:
- \([\text{N}_2] = 0,8 \, \text{mol/L}\]
Kev Hloov Pauv hauv N₂ = 1 – 0,8 = 0,2 mol/L
2. Stoichiometry ntawm kev hloov pauv:
\[
\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)
\]
Yog li, kev hloov pauv rau H₂ thiab NH₃:
– \([\text{H}_2] = 3 \cdot 0,2 = 0,6 \, \text{mol/L}\]
– \([\text{NH}_3] = 2 \cdot 0,2 = 0,4 \, \text{mol/L}\]
Mole equilibrium:
– \([\text{H}_2] = 3 – 0,6 = 2,4 \, \text{mol/L}\]
– \([\text{NH}_3] = 0 + 0,4 = 0,4 \, \text{mol/L}\]
3. Xam tus nqi \(K_c\):
\[
K_c = \frac{[\text{NH}_3]^2}{[\text{N}_2][\text{H}_2]^3}
\]
Hloov cov nqi:
– \([\text{NH}_3] = 0,4 \, \text{mol/L}\]
- \([\text{N}_2] = 0,8 \, \text{mol/L}\]
– \([\text{H}_2] = 2,4 \, \text{mol/L}\]
\[
K_c = \frac{(0,4)^2}{(0,8)(2,4)^3}
\]
\[
= \frac{0,16}{0,8 13,824}
\]
\[
= \frac{0,16}{11,0592}
\kwv yees li 0,0145
\]
Lo Lus Nug 2: Cov Nyhuv ntawm Kev Hloov Pauv hauv Kev Sib Sau Ua Ke
Ib qho N₂O₄(g) uas muaj ntau yuav lwj mus ua 2NO₂(g) hauv ib lub thawv kaw. Thaum muaj qhov kub thiab txias, qhov sib npaug tas mus li \(K_c\) yog 0,36. Yog tias qhov concentration pib ntawm N₂O₄(g) yog 1,0 M thiab tsis muaj NO₂(g) thaum pib, xam qhov concentration ntawm NO₂(g) thaum sib npaug.
Kev Sib Tham:
1. Siv ICE Rooj:
\[
\begin{aligned}
\text{Kev Tawm Tsam:} & \ \ \text{N}_2\text{O}_4(g) \rightleftharpoons 2\text{NO}_2(g) \\
\text{Initial:} & \ \ [\text{N}_2\text{O}_4]_{0} = 1.0 \, \text{M}, \ [\text{NO}_2]_{0} = 0 \\
\text{Hloov:} & \ \ [\text{N}_2\text{O}_4]_{eq} = 1.0 – x, \ [\text{NO}_2]_{eq} = 2x \\
\end{aligned}
\]
2. Txuas nrog \(K_c\):
\[
K_c = \frac{[\text{NO}_2]^2}{[\text{N}_2\text{O}_4]}
= \frac{(2x)^2}{1.0 – x}
= \frac{4x^2}{1 – x}
\]
3. Txheeb xyuas x:
\[
Kc = 0,36
\]
Yog li, kev hloov pauv:
\[
0,36 = \frac{4x^2}{1 – x}
\]
Kev sib tshooj hla:
\[
0,36(1 – x) = 4x^2
\]
\[
0,36 – 0,36x = 4x^2
\]
Tsiv txhua yam mus rau ib sab:
\[
4x^2 + 0,36x – 0,36 = 0
\]
4. Kev daws cov kab zauv plaub fab:
Siv cov qauv quadratic:
\[
x = \frac{-b^2 – 4ac}}{2a}
\]
Qhov twg a = 4, b = 0,36 thiab c = -0,36:
\[
x = \frac{-0,36 \pm \sqrt{(0,36)^2 – 4(4)(-0,36)}}{2(4)}
\]
\[
x = \frac{-0,36 \pm \sqrt{0,1296 + 5,76}}{8}
\]
\[
x = \frac{-0,36 \pm \sqrt{5,8896}}{8}
\]
Vim tias qhov kev sib sau ua ke tsis tuaj yeem yog qhov tsis zoo, peb xaiv cov hauv paus zoo:
\[
x \kwv yees li 0,36
\]
5. Kev sib xyaw ntawm NO₂:
\[
[\text{NO}_2]_{eq} = 2x = 2 \cdot 0,36 = 0,72 \, \text{M}
\]
Xaus
Kev nkag siab txog kev sib npaug ntawm cov tshuaj lom neeg yog qhov tseem ceeb rau kev kwv yees seb lub cev tshuaj lom neeg yuav ua li cas hauv qee qhov xwm txheej. Nrog kev xyaum thiab kev nkag siab zoo, peb tuaj yeem daws cov teeb meem uas cuam tshuam nrog lub tswv yim no, piav qhia txog qhov xwm txheej kawg ntawm lub cev, thiab nkag siab txog qhov sib txawv ntawm cov tshuaj lom neeg hauv lub cev kaw. Kev lees paub thiab siv qhov sib npaug tas mus li (K_c) yuav ua rau nws yooj yim dua los kwv yees qhov sib xyaw ntawm txhua hom tsiaj hauv lub cev ntawm qhov sib npaug.
