Introduction to Titration · 滴定介绍
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| titration/taɪˈtreɪʃn/ | 滴定 | dī dìng |
| equivalence point/ɪˈkwɪvələns pɔɪnt/ | 等当点 | děng dāng diǎn |
Finding strength drop by drop
- How much acid is really in this vinegar?
- Add a known base, one careful drop at a time.
- The moment it neutralizes, an indicator flips colour.
- That exact volume reveals the unknown concentration.
一滴一滴地测出浓度
- 这瓶醋里到底有多少酸?
- 加入已知的碱,一次小心地滴一滴。
- 中和的那一刻,指示剂变色。
- 那个精确的体积揭示了未知的浓度。
What a titration does
- A titration 滴定 finds an unknown concentration.
- You add a known solution until the reaction is just complete.
- The volume added tells you the unknown amount.
滴定做什么
- 滴定用来求未知的浓度。
- 你加入一份已知的溶液,直到反应恰好完成。
- 加入的体积告诉你未知的量。
A titration is used to find... · 滴定用于测定...
You add a known solution to determine an unknown concentration. · 加入已知溶液以确定未知浓度。
In a titration you slowly add a solution of ____ concentration. · 在滴定中，你缓慢加入浓度 ____ 的溶液。
The titrant has a known concentration; the analyte is unknown. · 滴定剂有已知浓度；分析物是未知的。
The equivalence point
- The equivalence point 等当点 is where the moles exactly match the reaction ratio.
- An indicator changes colour near it, marking the endpoint.
- Read the volume of titrant added at that moment.
等当点
- 等当点是摩尔数恰好符合反应比例的地方。
- 指示剂在它附近变色,标记出终点。
- 读出那一刻加入的滴定剂体积。
The equivalence point is where... · 等当点是...
At equivalence the reactants are present in the exact ratio. · 在等当点时，反应物以确切的比例存在。
Working out the concentration
- At the equivalence point, moles of acid match moles of base (for a 1 : 1 reaction).
- $M_a V_a = M_b V_b$ lets you solve for the unknown.
- Rearrange it to find whichever concentration you need.
算出浓度
- 在等当点,酸的摩尔数与碱的摩尔数相等(对 1 : 1 反应)。
- $M_a V_a = M_b V_b$ 让你解出未知量。
- 整理它,求出你需要的任一浓度。
Run a titration · 进行滴定操作
Add base to acid and watch the pH rise through the steep equivalence point. · 向酸中加入碱，观察 pH 值通过陡峭的等当点上升。
A good indicator changes colour at the equivalence point. · 良好的指示剂应在等当点变色。
The endpoint should match the equivalence point. · 终点应与等当点一致。
$M_1V_1 = M_2V_2$ works directly only for a 1-to-1 mole ratio. · $M_1V_1 = M_2V_2$ 仅在 1:1 摩尔比时直接使用。
Other ratios need the coefficients from the balanced equation. · 其他比例需要配平方程式中的系数。
$25\ \text{mL}$ of acid is neutralized by $20\ \text{mL}$ of $0.1\ \text{M}$ base (1 : 1).
- $M_a V_a = M_b V_b$ gives $M_a (25) = (0.1)(20)$.
- $M_a = 2/25 = 0.08\ \text{M}$.
$25\ \text{mL}$ 的酸被 $20\ \text{mL}$ 的 $0.1\ \text{M}$ 碱中和(1 : 1)。
- $M_a V_a = M_b V_b$ 给出 $M_a (25) = (0.1)(20)$。
- $M_a = 2/25 = 0.08\ \text{M}$。
$30\ \text{mL}$ of acid is neutralized by $15\ \text{mL}$ of $0.2\ \text{M}$ base (1 to 1). The acid's molarity (in M)? · $30\ \text{mL}$ 的酸被 $15\ \text{mL}$ 的 $0.2\ \text{M}$ 碱中和（1:1）。酸的摩尔浓度（M）是多少？
$M_a(30) = (0.2)(15) = 3$, so $M_a = 0.1\ \text{M}$. · $M_a(30) = (0.2)(15) = 3$，所以 $M_a = 0.1\ \text{M}$。
The endpoint (the indicator's colour change) should match the equivalence point, so pick an indicator that flips there. $M_1V_1 = M_2V_2$ holds only for a 1 : 1 mole ratio; otherwise include the ratio from the balanced equation. And measure volumes carefully -- the whole method depends on precise readings.
终点(指示剂变色)应与等当点相符,所以要选一个在那里变色的指示剂。$M_1V_1 = M_2V_2$ 只对 1 : 1 摩尔比成立;否则要带入配平方程的比例。而且要仔细测量体积——整个方法都依赖精确的读数。
A titration finds an unknown concentration by adding a known solution until the reaction is complete. At the equivalence point the moles match the reaction ratio, marked by an indicator. For a 1 : 1 reaction, $M_a V_a = M_b V_b$ solves for the unknown.
滴定通过加入已知溶液直到反应完成来求未知浓度。在等当点摩尔数符合反应比例,由指示剂标记。对 1 : 1 反应,$M_a V_a = M_b V_b$ 可解出未知量。