What Is the Law of Reciprocal Proportion With Definition Formula Proof and Examples
German chemist Jeremias Richter devised a simple method for comparing compounds and determining how two elements will combine to make another chemical in the late 18th century.
Law of Reciprocal Proportion
Jeremias Ritcher put forward the law of reciprocal proportions in 1792. According to the law of reciprocal proportions, we may calculate the proportion of elements in compound AC if we know the proportion of elements in compounds AB and BC. This law aided in our understanding of stoichiometry, which is the process of calculating the amounts of reactants and products in relation to reactions.
History of The Scientist
Jeremias Benjamin Richter (1762 - 1807)
Name: Jeremias Benjamin Richter
Born: 10 March 1762
Died: 4 May 1807
Field: Chemist
Nationality: German
What is the Law of Reciprocal Proportion?
The rule of reciprocal proportions is another name for the law of reciprocal proportions, which is also referred to as the law of equivalent proportions or permanent ratios.
According to Ritcher, "When two elements combine independently with a fixed mass of the third element, the ratio of their masses at that time is either the same or some whole number multiple of the ratio they mix."
Law of Reciprocal Proportion Examples
Let's take methane and calculate the ratio of the components. Hydrogen has a molecular weight of 1 g/mol, and carbon has a molecular weight of 12 g/mol. Since there are 4 hydrogen atoms for every carbon atom, the ratio is 12:4, which can be expressed as 3:1.
Therefore, both hydrogen and another element can be found in methane and water. This law states that the ratio of carbon to oxygen, which makes up the other element in both molecules, should be 3:8, or a straightforward multiple of that ratio.
We obtain 3:8 because water has an oxygen to carbon ratio of 8, and methane has an oxygen to carbon ratio of 3. Let's check to see whether this is accurate: the ratio of carbon to oxygen in carbon dioxide is 12:32.
Let's look at another illustration, beginning with sodium chloride. The molecular weights of sodium and chloride are 23 and 35 g/mol, respectively. This makes the ratio 23:35.
Let's now examine hydrochloric acid with a 35:1 ratio. The ratio we would anticipate to observe if we combined salt and hydrogen is 23:1. Yes, these come together to produce sodium.
Limitations of Law of Reciprocal Proportion
Differences similar to those seen in the law of constant proportions are produced by the element's isotopes. The synthesis of a number of chemicals should thus use the same isotope or a combination of isotopes.
The law only applies to a tiny subset of products that exhibit the disputed property since there are only a finite number of elements that will combine with the third element and also with one another.
Applications of Law of Reciprocal Proportion
We can now understand stoichiometry thanks to this law. This is how the quantities of the reactants and products in relation to the reaction are calculated. The law that exists now makes sense because every element has a specific molecular weight. To create an elemental compound, each element is added in a ratio of whole numbers.
Solved Examples
1. What made the law of reciprocal proportions significant?
It aided in the discovery of novel chemicals
It contributed to our current understanding of stoichiometry.
It assisted scientists in determining complex sizes.
The periodic table was made possible by it.
Ans: The correct answer is option B. As the law of reciprocal proportions plays an important role in studying and understanding the basic rules of stoichiometry.
2. Carbon is found in three different compounds: carbon dioxide (27.27%), carbon disulfide (15.79%), and sulphur dioxide (50%) Clearly demonstrate how the data exemplifies the law of reciprocal proportions.
Ans:
Carbon Compound
Let us take Carbon dioxide.
The percentage of carbon is 27.27
Percentage of oxygen (100 – 27.27) is 72.73
27.27 g of carbon reacts with 72.73 g of oxygen.
1 g of carbon joins with 72.73 / 27.27 => 2.67 g of oxygen.
Let us take Carbon disulfide.
Percentage of carbon = 15.79
Percentage of sulphur (100 – 15.79) is 84.21
15.79 g of carbon reacts with 84.21 g of sulphur.
Hence, 1 g of carbon reacts with \[\frac{84.21}{15.79}\] = 5.33 g of sulphur.
The ratio of different masses of sulphur and oxygen joining with a fixed mass of carbon is 5.33: 2.67.
That is, 2: 1. —> [1]
Let us take Sulphur Dioxide,
Percentage of sulphur = 50
Percentage of oxygen = 100 – 50 = 50
50 g of sulphur reacts with 50 g of oxygen.
The ratio of the mass of sulphur to oxygen is 50: 50,
That is, 1:1 —> [2]
A straightforward whole-number multiple of the first ratio is the second ratio. The information serves as an example of the law of reciprocal proportions.
3. Different oxygen content ratios in the various nitrogen oxides demonstrate the following law:
The Law of reciprocal proportions
The Law of multiple proportions
The Law of constant proportions
The Law of conservation of mass
Ans: Option A offers the right response. The law of multiple proportions, which states that when two elements combine in more than one proportion to form one or more compounds, the weight of one element that combines with the given weight of other elements is in the ratio of the small whole number, is demonstrated by the different proportions of oxygen in the various oxides of nitrogen.
Important Points to Remember
The rule of reciprocal proportions is another name for the law of reciprocal proportions, which is also referred to as the law of equivalent proportions or permanent ratios.
One of the fundamental laws of stoichiometry, along with definite and various proportions laws, is this one.
German physicist Jeremias Richter proposed the statute in 1791.
Conclusion
With the law's consent, tables of equivalent element weights might be made. These equivalent weights were frequently used by chemists in the nineteenth century. Two further stoichiometric laws are the law of definite proportions and the law of many proportions. The law of definite proportions is the formula for any compound formed between components A and B.
FAQs on Law of Reciprocal Proportion in Chemistry Explained Clearly
1. What is the Law of Reciprocal Proportion?
Law of Reciprocal Proportion states that when two elements combine separately with a fixed mass of a third element, the masses of the two elements that combine with each other are in the same ratio or a simple whole-number multiple of that ratio. This law is also called the Law of Reciprocal Proportions or Richter’s Law.
- It relates the combining masses of three elements.
- It supports the atomic theory and the concept of fixed combining ratios.
- It is closely connected to the Law of Multiple Proportions.
2. Who gave the Law of Reciprocal Proportion?
The Law of Reciprocal Proportion was proposed by Jeremias Benjamin Richter in 1792.
- Richter studied the quantitative relationships in chemical reactions.
- His work laid the foundation for stoichiometry and atomic mass relationships.
- The law is sometimes referred to as Richter’s Law in his honor.
3. Can you give an example of the Law of Reciprocal Proportion?
A common example of the Law of Reciprocal Proportion involves hydrogen, oxygen, and carbon forming H2O and CO2.
- In H2O, 2 g of H combine with 16 g of O.
- In CO2, 12 g of C combine with 32 g of O.
- So, 16 g of O combine with 2 g of H and 6 g of C (since 32 g O combine with 12 g C).
- The ratio of H:C = 2:6 = 1:3.
- In methane (CH4), 12 g of C combine with 4 g of H, giving H:C = 1:3.
4. How is the Law of Reciprocal Proportion related to the Law of Multiple Proportions?
The Law of Reciprocal Proportion is an extension of the Law of Multiple Proportions because both deal with simple whole-number mass ratios in chemical combinations.
- The Law of Multiple Proportions compares different compounds formed by the same two elements.
- The Law of Reciprocal Proportion compares masses of two elements that separately combine with a fixed mass of a third element.
- Both laws support Dalton’s atomic theory.
5. What is the formula statement of the Law of Reciprocal Proportion?
The formal statement of the Law of Reciprocal Proportion is: if element A combines with fixed mass of B and also with fixed mass of C, then the ratio of masses of B and C that combine with A is the same or a simple multiple of the ratio in which B and C combine with each other.
- Let A combine with B and C separately.
- If mass of B = x and mass of C = y (for fixed A), then B:C = x:y.
- When B and C combine, their ratio will be x:y or a simple whole-number multiple.
6. Why is the Law of Reciprocal Proportion important in chemistry?
The Law of Reciprocal Proportion is important because it supports the concept that elements combine in simple whole-number ratios based on atomic masses.
- It provides experimental evidence for Dalton’s atomic theory.
- It helps in understanding stoichiometric relationships.
- It confirms the consistency of chemical combination laws.
7. How do you verify the Law of Reciprocal Proportion using experimental data?
To verify the Law of Reciprocal Proportion, compare the masses of two elements that separately combine with a fixed mass of a third element and then compare their ratio when they combine with each other.
- Step 1: Record mass ratios in compounds AB and AC.
- Step 2: Calculate the ratio of B:C for a fixed mass of A.
- Step 3: Compare this ratio with the mass ratio in compound BC.
- Step 4: Check if the ratios are equal or simple whole-number multiples.
8. What is the difference between Law of Definite Proportions and Law of Reciprocal Proportion?
The Law of Definite Proportions states that a compound always contains elements in a fixed mass ratio, whereas the Law of Reciprocal Proportion compares mass ratios across three different elements.
- Definite Proportions: Concerned with one compound only.
- Reciprocal Proportion: Involves three elements and multiple compounds.
- Both describe fixed and simple mass relationships in chemical reactions.
9. What are the limitations of the Law of Reciprocal Proportion?
The Law of Reciprocal Proportion mainly applies to simple chemical compounds and may not clearly apply to complex or non-stoichiometric compounds.
- It assumes pure substances and accurate mass measurements.
- It may not directly apply to compounds with variable composition.
- Modern atomic theory explains it more precisely using atomic masses.
10. How does the Law of Reciprocal Proportion support Dalton’s atomic theory?
The Law of Reciprocal Proportion supports Dalton’s atomic theory by showing that elements combine in simple whole-number ratios based on fixed atomic masses.
- Atoms combine in fixed numerical ratios.
- Mass ratios reflect relative atomic masses.
- The law provides quantitative evidence for the atomic nature of matter.
