等比定律
由于原子太小而无法观察，因此必须使用大量原子来确定它们的结构和行为。我们可以尝试根据这些研究的结果建立一个与真实事物相似的原子的假设模型。
共价（化学）键将分子中的一个或多个原子结合在一起。原子被表示为圆形，中间有一个原子核（包含质子和中子），周围环绕着一个或多个同心圆，代表原子的“壳”或“能级”，原子核周围的电子位于其中，标记表示原子核电子。每次。分子是物质的最小单位，仍然可以归类为同一物质。它由化学连接在一起的两个或多个原子组成。
质量守恒定律
A Mass cannot be generated or destroyed in an isolated system, but it can be converted from one form to another.
根据质量守恒定律，在低能热力学过程中，反应物的质量必须等于产物的质量。人们认为质量守恒是由经典力学的一些假设定义的。在量子力学和狭义相对论的帮助下，质量守恒定律后来被修正到能量和质量现在是一个守恒量的地步。质量守恒是由安托万·洛朗·拉瓦锡于 1789 年发现的。
Formula of Law of Conservation of Mass
In fluid mechanics and continuum mechanics, the law of conservation of mass can be stated in differential form using the continuity equation as:
∂ρ∂t +▽ (ρv) = 0
where;
- ρ is the density,
- t is the time,
- v is the velocity, and
- ▽ is the divergence.
质量守恒定律的例子
- 燃烧过程：木材的燃烧是质量守恒，因为木材的燃烧涉及氧气、二氧化碳、水蒸气和灰烬。
- 化学反应：为得到一分子分子量为10的H2O水，将分子量为2的氢气与分子量为8的氧气相加，从而保持质量。
质能守恒定律
The law of mass-energy conservation, which states that the total mass and energy of a system remain constant. The knowledge that mass and energy can be converted from one to the other is incorporated in this revision. because the amount of energy produced or used in a normal chemical reaction is so small In a reaction, the total number of atoms stays the same.
这个假设使我们能够将化学反应表述为一个平衡方程，其中方程两边的每个元素的摩尔数相同。该定律的另一个重要应用是确定气态反应物和产物的质量。如果已知固体或液体反应物和产物的总和，则任何残留质量都可以归因于气体。
尽管看起来燃烧会破坏物质，但在篝火之后仍会保留相同数量（或质量）的物质。当木材燃烧时，它会与氧气结合并转化为灰烬、二氧化碳和水蒸气等。气体漂浮在空气中，只留下灰烬。
恒比例定律
According to the law of constant proportions, chemical compounds are made up of elements that are present in a stable mass ratio. This means that regardless of the source, each pure sample of a chemical will always have the same elements in the same mass ratio.
例如，纯水总是具有恒定的氢氧质量比（一克水由大约 0.11 克氢和 0.88 克氧组成，比例为 1:8）。根据恒比例定律，化合物由具有恒定质量比的元素组成。这表明，无论来源如何，任何纯化学样品都将始终具有相同质量比的相同元素。
法国科学家约瑟夫·普鲁斯特（Joseph Proust）从他对硫化物、金属氧化物和硫酸盐的研究中，于 1794 年创造了恒定比例定律。在 18 世纪，这一规定遭到了科学界的强烈反对。道尔顿原子理论的引入支持了这一定律，瑞典化学家雅各布·贝采利乌斯在 1811 年证明了这两个概念之间的关系。
等比例定律的例外情况
恒定比例定律并不适用于所有化学物质，尽管它在化学发展中很重要。该法律有一些例外情况，如下所述。
- 某些非化学计量化合物中的成分组成因样品而异。相反，多重比例定律支配着这些化合物。
- 方铁矿是一种化学式为 FeO 的氧化铁，就是这样一个例子。铁与氧原子的比例可以在 0.83 和 0.95 之间变化。
- 这是由于样品中的晶体空隙，这是由混乱的原子排列产生的。
- 化合物组成元素的同位素组成可能因样品而异。质量比可能因此而波动。
- 由于许多深部地球和地壳过程中同位素的优先浓度，样品间质量比的变化在地球化学测年过程中非常有价值。
- 许多海军陆战队、大气，甚至天体过程都受此影响。尽管影响很小，但现代仪器已经解决了测量它们的障碍。
- 由于天然聚合物的成分范围很广，因此不同的样品可能具有不同的质量比例。
道尔顿定律
In his 1804 publication, A New System of Chemical Philosophy, English chemist and meteorologist John Dalton introduced the concept of multiple proportions, often known as Dalton’s law. It’s a stoichiometric rule. The law asserts that when elements form compounds, the proportions of the components in those chemical compounds can be stated in small whole-number ratios. It was based on Dalton’s observations of atmospheric gas reactions.
例如，碳原子和氧原子可以反应生成一氧化碳 (CO) 和二氧化碳 (CO 2 ) (CO 2 )。 CO 2中氧的量与碳的量相比具有1:2的固定比率，这是整数的比率。 CO 中的比例为 1:1。
道尔顿在他的原子结构和组成理论中提出了所有物质都是由原子的不同组合组成的想法，这些原子是物质不可分割的组成部分。这些规则为我们目前对原子结构和组成以及分子和化学方程式等概念的理解奠定了基础。
示例问题
问题 1：陈述质量和能量守恒定律。
回答：
Although mass and energy cannot be converted, their total remains constant during any physical or chemical transformation.
The mass of the products in a nuclear reaction is slightly less than that of the reactants. The reason for this is that the lost mass is transformed into energy using the following equation:
Here,
m = mass lost
c = velocity of light
问题 2：如果加热 4.2 g KClO3，结果是 1.92 g O 和 2.96 g KCl。证明这个结果符合质量守恒定律。
回答：
KClO3 → KCl + 3/2 O2
Sum of masses of products
1.92 + 2.96 = 4.88 g
The difference between the total mass of reactants and products and the sum of products is calculated as follows:
0.02 g = 4.9 – 4.88
问题3：在这种情况下，该值必须为零；然而，对于实验误差，质量守恒定律仍然适用。
如果它既不能被创造也不能被毁灭，那么终极能量的来源是什么？
回答：
The Big Bang is the source from which we obtain energy. At the beginning of time, all energy was produced. As the universe expanded, it created a variety of materials, which in turn produced energy.
问题 4：5.3 g 碳酸钠和 6 g 乙酸在一个过程中合并。最终产物为 2.2 g 二氧化碳、0.9 g 水和 8.2 g 乙醇钠。证明这些发现符合质量守恒定律。
乙酸钠 + 二氧化碳 + 水 碳酸钠 + 乙酸 乙酸钠 + 二氧化碳 + 水
回答：
Sodium carbonate interacts with ethanoic acid to generate sodium ethanoate, carbon dioxide, and water in the given reaction. 5.3 gram of sodium carbonate (Given)
Mass of sodium carbonate = 5.3 g (Given)
Mass of ethanoic acid = 6 g (Given)
Mass of sodium ethanoate = 8.2 g (Given)
Mass of carbon dioxide = 2.2 g (Given)
Mass of water = 0.9 g (Given)
Now, total mass before the reaction = (5.3 + 6) g= 11.3 g
After the reaction, the total mass is (8.2 + 2.2 + 0.9) g.(11.3 g)
Before the reaction, the total mass was = the total mass after the reaction.
As a result, the observations are consistent with the law of mass conservation.
问题5：质量守恒定律导致道尔顿原子论的哪个假设？
回答：
‘The relative number and types of atoms are constant in a given compound,’ according to Dalton’s atomic theory, which is based on the rule of conservation of mass. In a chemical reaction, atoms cannot be generated or destroyed.’
Postulates of Dalton’s atomic theory
- Atoms are the indestructible building blocks of matter..
- All of the atoms of a given element have the same properties, including mass. This can alternatively be expressed as an element’s atoms all having the same mass, whereas other elements have varying masses.
- Compounds are formed when atoms of different elements mix in specific proportions.
- Atoms do not make or destroy themselves. This means that no atoms are generated or destroyed during chemical processes.
- The rearrangement of existing atoms results in the production of new products (compounds) (reactants).
- The mass, size, and many other chemical and physical properties of an element’s atoms are all the same.
- Even so, the mass, size, and many other chemical and physical properties of atoms from two different elements differ.
问题6：当氢气和氧气以1:8的质量比混合时会形成水。与 3 g 氢气完全反应需要多少氧气？
回答：
It is given that the ratio of hydrogen and oxygen by mass to form water is 1:8.
Then, the mass of oxygen gas required to react completely with 1 g of hydrogen gas is 8 g.
Therefore, the mass of oxygen gas required to react completely with 3 g of hydrogen gas is 8 × 3 g = 24 g.
问题 7：质量守恒定律导致了道尔顿原子论的哪个假设？
回答：
The following is the postulate of Dalton’s atomic theory, which is based on the rule of mass conservation:
In a chemical reaction, atoms are indivisible particles that cannot be formed or destroyed.