Equilibrium constants · 平衡常数
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| equilibrium constant/ˌiːkwɪˈlɪbrɪəm ˈkɒnstənt/ | 平衡常数 | píng héng cháng shù |
| partial pressure/ˈpɑːʃl ˈpreʃə/ | 分压 | fēn yā |
| mole fraction/məʊl ˈfrækʃn/ | 摩尔分数 | mó ěr fēn shù |
Putting a number on balance
- The equilibrium constant 平衡常数 links the amounts of products and reactants.
- For concentrations we use $K_c$; for gases, $K_p$.
- Only temperature changes its value.
给平衡定一个数
- 平衡常数(equilibrium constant)联系产物和反应物的量。
- 对浓度我们用 $K_c$;对气体,$K_p$。
- 只有温度改变它的值。
The equilibrium constant in terms of concentrations is written as . · 用浓度表示的平衡常数写作。
Kc = products over reactants, each raised to its mole number. · Kc = 产物除以反应物,每个提升到它的摩尔数。
$K_c$
For $a\text{A} + b\text{B} \rightleftharpoons c\text{C} + d\text{D}$:
- Square brackets mean concentration in $\dfrac{\text{mol}}{\text{dm}^3}$; the powers are the equation's numbers.
Dynamic equilibrium: forward and reverse rates become equal and the concentrations stay constant
$K_c$
对 $a\text{A} + b\text{B} \rightleftharpoons c\text{C} + d\text{D}$:
- 方括号表示浓度,单位 $\dfrac{\text{mol}}{\text{dm}^3}$;幂是方程的系数。
动态平衡:正反应和逆反应速率变得相等,浓度保持恒定
Le Chatelier and Kc · 勒夏特列原理与 Kc
Change temperature, pressure or concentration and watch the equilibrium shift · 平移 to oppose it — Kc itself only changes with temperature. · 改变温度、压强或浓度,看平衡移动以对抗这一改变——而 Kc 本身只随温度变化。
In the expression for Kc, the concentrations of the products are: · 在 Kc 的表达式中,产物的浓度是:
Kc = [products]^powers / [reactants]^powers, with the powers taken from the balanced equation. · Kc = [产物]^幂 / [反应物]^幂,幂取自配平的方程。
$K_p$ and partial pressure 分压
- For gases we use partial pressures ($K_p$).
- The partial pressure of a gas is its share of the total:
$K_p$ 和分压
- 对气体我们用分压(partial pressures,$K_p$)。
- 一个气体的分压是它占总压的份额:
The partial pressure of a gas equals: · 一个气体的分压等于:
Partial pressure = mole fraction × total pressure; Kp is written using these. · 分压 = 摩尔分数 × 总压;Kp 用这些写出。
Kp is written using partial pressures rather than concentrations. · Kp 用分压而不是浓度写出。
For gas-phase equilibria, Kp uses the partial pressures of the gases. · 对气相平衡,Kp 用气体的分压。
What changes K
- Only temperature changes the value of $K_c$ or $K_p$.
- Changing concentration or pressure, or adding a catalyst, shifts the position but leaves $K$ unchanged.
什么改变 K
- 只有温度改变 $K_c$ 或 $K_p$ 的值。
- 改变浓度或压强,或加入一个催化剂,移动位置但使 $K$ 不变。
Which change alters the value of the equilibrium constant? · 哪个改变改变平衡常数的值?
Only temperature changes K; the others shift the position of equilibrium but leave K unchanged. · 只有温度改变 K;其他的移动平衡位置但使 K 不变。
You've got it
- $K_c = \dfrac{[\text{C}]^c[\text{D}]^d}{[\text{A}]^a[\text{B}]^b}$ (powers from the equation; $\dfrac{\text{mol}}{\text{dm}^3}$)
- $K_p$ uses partial pressures = mole fraction 摩尔分数 × total pressure
- only temperature changes $K$; concentration/pressure/catalyst shift the position only
你掌握了
- $K_c = \dfrac{[\text{C}]^c[\text{D}]^d}{[\text{A}]^a[\text{B}]^b}$(幂来自方程;$\dfrac{\text{mol}}{\text{dm}^3}$)
- $K_p$ 用分压 = 摩尔分数 × 总压
- 只有温度改变 $K$;浓度/压强/催化剂只移动位置