Energy Diagrams · 能量图
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| enthalpy/enˈθælpi/ | 焓 | hán |
Drawing heat as height
- Picture reactants and products as blocks at different heights.
- The higher one holds more stored chemical energy.
- Drop from high to low and heat spills out.
- Climb from low to high and heat must be poured in.
把热画成高度
- 把反应物和产物想象成不同高度的方块。
- 更高的那个储存更多的化学能。
- 从高落到低,热就溢出。
- 从低爬到高,就必须注入热。
Reactants and products as levels
- An energy diagram draws reactants and products as horizontal levels.
- Their heights show how much enthalpy 焓 (stored energy) each holds.
- The gap between them is $\Delta H$.
反应物和产物作为能级
- 能量图把反应物和产物画成水平的能级。
- 它们的高度显示各自储存多少焓(储存的能量)。
- 它们之间的间隔就是 $\Delta H$。
The vertical gap between the reactant and product levels is $\Delta H$. · 反应物与产物能级之间的垂直差即为$\Delta H$。
That height difference is the enthalpy change. · 那个高度差就是焓变。
The exothermic shape
- Exothermic: the products sit lower than the reactants.
- Energy is released as the reaction "falls."
- So $\Delta H$ is negative.
放热的形状
- 放热:产物比反应物低。
- 反应"下落"时放出能量。
- 所以 $\Delta H$ 为负。
On an energy diagram, products below reactants means the reaction is... · 在能量图上，产物低于反应物意味着该反应是...
Lower products mean energy was released -- exothermic. · 产物较低意味着能量被释放——这是放热反应。
An exothermic reaction has a negative $\Delta H$. · 放热反应具有负的 $\Delta H$。
Products lower than reactants gives a negative $\Delta H$. · 产物低于反应物给出负的$\Delta H$。
The endothermic shape
- Endothermic: the products sit higher than the reactants.
- Energy is absorbed as the reaction "climbs."
- So $\Delta H$ is positive.
吸热的形状
- 吸热:产物比反应物高。
- 反应"上爬"时吸收能量。
- 所以 $\Delta H$ 为正。
An endothermic energy diagram · 吸热能量图
When a reaction absorbs energy, the products sit higher than the reactants. · 当反应吸收能量时，产物的位置高于反应物。
An endothermic reaction has products that are... · 吸热反应的产物是...
Absorbing energy raises the products above the reactants. · 吸收能量使产物位置高于反应物。
Products at $30\ \text{kJ}$, reactants at $80\ \text{kJ}$. Exothermic or endothermic?
- The products are lower, so energy was released.
- $\Delta H = 30 - 80 = -50\ \text{kJ}$, which is exothermic.
产物在 $30\ \text{kJ}$,反应物在 $80\ \text{kJ}$。放热还是吸热?
- 产物更低,所以放出了能量。
- $\Delta H = 30 - 80 = -50\ \text{kJ}$,是放热的。
Reactants at $60\ \text{kJ}$, products at $90\ \text{kJ}$. The value of $\Delta H$ (in kJ)? · $60\ \text{kJ}$ 处为反应物，$90\ \text{kJ}$ 处为产物。$\Delta H$ 的值（单位为 kJ）是多少？
$\Delta H = 90 - 60 = +30\ \text{kJ}$ (endothermic). · $\Delta H = 90 - 60 = +30\ \text{kJ}$（吸热）。
$\Delta H$ equals products minus . · $\Delta H$等于产物减去。
$\Delta H$ = final (products) minus initial (reactants). · $\Delta H$ = 终态（产物）减去初态（反应物）。
Read $\Delta H$ as products minus reactants (final minus initial). Products lower means exothermic and a negative $\Delta H$; products higher means endothermic and positive. Do not confuse this enthalpy diagram (heights are stored energy) with a kinetics profile's activation-energy hump.
把 $\Delta H$ 读作产物减反应物(末减初)。产物更低意味着放热、$\Delta H$ 为负;产物更高意味着吸热、为正。别把这张焓图(高度是储存的能量)与动力学图的活化能山峰混淆。
An energy diagram draws reactants and products as levels whose heights are their enthalpy. Products lower than reactants means exothermic (negative $\Delta H$); products higher means endothermic (positive $\Delta H$). The vertical gap, products minus reactants, is $\Delta H$.
能量图把反应物和产物画成能级,高度是它们的焓。产物比反应物低意味着放热($\Delta H$ 为负);产物更高意味着吸热($\Delta H$ 为正)。竖直间隔,即产物减反应物,就是 $\Delta H$。