Reaction calculations · 反应计算
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| mole ratio/məʊl ˈreɪʃɪəʊ/ | 摩尔比 | mó ěr bǐ |
| yields/jiːldz/ | 产率 | chǎn lǜ |
Predicting how much you get
- A balanced equation is a recipe: it tells you exactly how much product a reaction makes.
- Reaction calculations use moles to work this out.
预测你得到多少
- 一个平衡的方程式是一个配方:它告诉你一个反应制造多少产物。
- 反应计算用摩尔算出这个。
Balance the equation · 配平方程式
Step the coefficients until every element has the same number of atoms on both sides. · 调整系数直到每种元素在方程式两边具有相同数量的原子。
Reaction calculation route · 反应计算路径
Follow a known mass through a balanced equation to the answer. · 根据已知质量通过配平的方程式推导出答案。
How many moles are in 4 g of hydrogen gas (Mr = 2)? · 4 g 氢气（Mr = 2）中含有多少摩尔？
moles = 4 ÷ 2 = 2. · moles = 4 ÷ 2 = 2。
The big numbers in a balanced equation give the ______ ratio. · 配平方程式中的大数字表示 ______ 比。
Reactions combine in whole-number mole ratios. · 反应物以整数摩尔比结合。
The mole ratio 摩尔比
- The big numbers in a balanced equation give the mole ratio of reactants and products.
- In 2H₂ + O₂ → 2H₂O, 2 moles of hydrogen make 2 moles of water.
A titration measures exactly how much acid reacts with a base
摩尔比
- 一个平衡方程式中的大数字给出反应物和产物的摩尔比(mole ratio)。
- 在 2H₂ + O₂ → 2H₂O 中,2 摩尔氢制造 2 摩尔水。
一次滴定测量恰好多少酸与一种碱反应
In 2H₂ + O₂ → 2H₂O, the mole ratio of H₂ to H₂O is: · 在 2H₂ + O₂ → 2H₂O 中，H₂ 与 H₂O 的摩尔比为：
2 moles of H₂ give 2 moles of water. · 2 摩尔 H₂ 生成 2 摩尔水。
Put the reaction-calculation steps in order. · 将反应计算步骤按正确顺序排列。
Mass → moles → ratio → moles → mass. · 质量 → 摩尔 → 比例 → 摩尔 → 质量。
The method
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- Find the moles of the substance you know (mass ÷ Mr).
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- Use the mole ratio to find moles of the substance you want.
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- Convert back to mass (moles × Mr) if needed.
Worked example. How much water from 4 g of hydrogen (Mr = 2) burning in oxygen? Moles of H₂ = 4 ÷ 2 = 2. The ratio H₂ : H₂O is 2 : 2, so 2 moles of water form. Mass = 2 × 18 = 36 g.
方法
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- 找出你知道的物质的摩尔(质量 ÷ Mr)。
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- 用摩尔比找出你想要的物质的摩尔。
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- 如果需要,转换回质量(摩尔 × Mr)。
例题。 4 g 氢(Mr = 2)在氧中燃烧得到多少水?H₂ 的摩尔 = 4 ÷ 2 = 2。比 H₂ : H₂O 是 2 : 2,所以形成 2 摩尔水。质量 = 2 × 18 = 36 g。
If 2 moles of water form (Mr of water = 18), what mass of water is that? · 如果生成了 2 摩尔水（水的 Mr = 18），其质量是多少？
mass = 2 × 18 = 36 g. · mass = 2 × 18 = 36 g。
Why it matters
- These calculations let chemists and factories work out yields 产率 and amounts needed.
- They avoid waste and predict exactly how much product to expect.
Use the mole ratio, not the mass ratio. Reactions combine in whole-number ratios of moles, not grams. Always convert mass to moles before applying the ratio from the equation.
为什么它重要
- 这些计算让化学家和工厂算出产率和需要的量。
- 它们避免浪费并恰好预测预期多少产物。
用摩尔比,不是质量比。 反应以摩尔的整数比结合,不是克。在应用方程式中的比之前,总是把质量转换为摩尔。
You've got it
- the balanced equation gives the mole ratio of reactants to products
- method: mass → moles → (ratio) → moles → mass
- always work in moles, not masses, when using the ratio
你掌握了
- 平衡的方程式给出反应物对产物的摩尔比
- 方法:质量 → 摩尔 →(比)→ 摩尔 → 质量
- 使用比时总是以摩尔工作,不是质量