Heat Capacity and Calorimetry · 热容与量热法
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| specific heat capacity/spəˈsɪfɪk hiːt kəˈpæsɪti/ | 比热容 | bǐ rè róng |
| calorimetry/ˌkælɔːˈrɪmətri/ | 量热法 | liàng rè fǎ |
Why water is so hard to heat
- Sand at the beach burns your feet while the sea stays cool.
- Same sunshine, wildly different temperatures.
- Some materials soak up lots of energy per degree; others little.
- A simple formula captures exactly how much.
为什么水这么难加热
- 海滩上的沙子烫脚,而海水却保持凉爽。
- 同样的阳光,温度却天差地别。
- 有些材料每升高一度就吸收大量能量;有些则很少。
- 一个简单的公式精确抓住这个量。
Specific heat capacity
- Specific heat capacity 比热容 is the energy to warm 1 g by 1 degree.
- Water's is high, so it heats and cools slowly.
- The bigger it is, the more energy each degree costs.
比热容
- 比热容是把 1 g 升高 1 度所需的能量。
- 水的比热容高,所以它加热和冷却都很慢。
- 它越大,每一度花费的能量越多。
Water's high specific heat means it resists changes in temperature. · 水的高比热意味着它抵抗温度变化。
A high $c$ means lots of energy is needed per degree. · 高$c$意味着每度需要大量能量。
A substance with a high specific heat warms up ____ than one with a low value. · 比热高的物质升温比比热低的物质____。
High specific heat means more energy per degree, so slower warming. · 高比热意味着每度需要更多能量，因此升温较慢。
The heat equation
- The heat absorbed or released is:
- Here $m$ is mass, $c$ the specific heat, and $\Delta T$ the temperature change.
热量方程
- 吸收或放出的热量是:
- 这里 $m$ 是质量,$c$ 是比热容,$\Delta T$ 是温度变化。
In $q = mc\Delta T$, the symbol $\Delta T$ is the... · 在$q = mc\Delta T$中，符号$\Delta T$代表...
Use the change in temperature, not the absolute value. · 使用温度的变化量，而不是绝对值。
A metal absorbs $500\ \text{J}$, warming $50\ \text{g}$ by $20$ degrees. Its specific heat $c$ (in J/g per degree, 2 decimals)? · 金属吸收了 $500\ \text{J}$, 温度升高了 $50\ \text{g}$ 度。它的比热容为 $20$ 度。其比热 $c$ （单位为 J/g·度，保留 2 位小数）？
$c = q/(m\Delta T) = 500/(50\times20) = 0.5$.
Calorimetry
- Calorimetry 量热法 measures heat by watching a temperature change.
- Heat lost by one thing equals heat gained by another.
- That balance lets us find an unknown quantity.
量热法
- 量热法通过观察温度变化来测量热量。
- 一样东西损失的热等于另一样得到的热。
- 这种平衡让我们求出未知量。
Heat needed to warm water · 加热水所需的热量
The heat needed depends on mass, specific heat capacity and temperature change (q = mcΔT). · 所需热量取决于质量、比热容和温度变化 (q = mcΔT)。
In calorimetry, the heat lost by the hot object equals the heat... · 在量热法中，热物体失去的热量等于冷物体...
Energy is conserved -- heat lost equals heat gained. · 能量守恒——失去的热量等于获得的热量。
Heat $200\ \text{g}$ of water ($c = 4.18$) by $10$ degrees. How much heat?
- $q = mc\Delta T = 200 \times 4.18 \times 10$.
- $q = 8360\ \text{J}$.
把 $200\ \text{g}$ 水($c = 4.18$)加热 $10$ 度。需要多少热量?
- $q = mc\Delta T = 200 \times 4.18 \times 10$。
- $q = 8360\ \text{J}$。
Heat $100\ \text{g}$ of water ($c = 4.18$) by $5$ degrees. The heat (in J)? · 水的$100\ \text{g}$（$c = 4.18$）升高$5$度。所需热量（单位：J）是多少？
$q = mc\Delta T = 100 \times 4.18 \times 5 = 2090\ \text{J}$.
Use the temperature change ($\Delta T$), not the absolute temperature, in $q = mc\Delta T$. Water's high specific heat is exactly why it resists temperature change. And in calorimetry, the heat lost by the hot object equals the heat gained by the cold one, because energy is conserved.
在 $q = mc\Delta T$ 中用温度变化($\Delta T$),而不是绝对温度。水高的比热容正是它抵抗温度变化的原因。而且在量热法中,热物体损失的热等于冷物体得到的热,因为能量守恒。
Specific heat capacity is the energy to warm 1 g by 1 degree, and the heat is $q = mc\Delta T$ (using the temperature change). Calorimetry measures heat from a temperature change, using the rule that heat lost equals heat gained.
比热容是把 1 g 升高 1 度所需的能量,而热量是 $q = mc\Delta T$(用温度变化)。量热法通过温度变化来测量热量,利用"损失的热等于得到的热"这条规则。