Question

Which of the following statements is known as the Berzelius Hypothesis?
(A) Equal volumes of all the gases comprise an equal number of atoms under the similar conditions of the temperature and pressure.
(B) Equal volumes of all the gases comprise an equal number of moles under the similar conditions of the temperature and pressure.
(C) Equal pressures of all the gases comprise an equal number of atoms under the similar conditions of the temperature and volume.
(D) Equal pressures of all the gases comprise an equal number of moles under the similar conditions of the temperature and volume.

Answer 1

Hint: The Berzelius hypothesis was a contradiction to Dalton’s hypothesis. According to the Berzelius hypothesis, if similar conditions are imposed, equal volumes of gases will have equal atom numbers and the atoms could also be divisible.

Complete answer:
What is the Berzelius hypothesis?
First of all, let us know what the Berzelius hypothesis is. The Berzelius hypothesis was proposed by the Swedish chemist Jons Jacob Berzelius who was known as the father of Swedish chemistry.
According to the Berzelius hypothesis, equal volume of all gases will contain equal numbers of atoms under similar conditions of temperature and pressure.
When this concept of combining volume was applied, it directly indicated that the atoms are divisible which contradicted Dalton’s hypothesis.
Example:
Now, let us elaborate the hypothesis with the help of an example. Let us consider the reaction between hydrogen and chlorine atoms to produce hydrogen chloride molecules, the reaction can be given as follows:
$H + Cl\rightarrow HCl$
Now, if we consider that 1 volume of hydrogen and 1 volume of chlorine are reacting, then 2 volumes of hydrogen chloride will be produced. If 1 volume of hydrogen gas contains n number of atoms and 1 volume of chlorine gas also contains n number of atoms, then the produced hydrogen chloride will contain 2n number of molecules.
$H + Cl\rightarrow HCl$
$1V + 1V\rightarrow 2V$
$n(atoms) + n(atoms)\rightarrow 2n(molecules)$
Now, if we divide the above equation by 2n, then we will have:
$\dfrac{1}{2}(atom) + \dfrac{1}{2}(atom)\rightarrow 1(molecule)$
Hence, it can be stated that half hydrogen will react with half chloride atom to produce 1 hydrogen chloride molecule.
From the above equation, it is clear that when the Berzelius hypothesis is applied, then the atoms are supposed to be divisible which creates a direct conflict with Dalton’s hypothesis which stated that the atoms are indivisible and the ultimate particles of the elements.
Available answer options:
Now let’s check the available answer options.

• According to the hypothesis, under similar conditions, equal volume of all gases will contain equal numbers of atoms. Moles, in chemistry, are the fundamental unit that is used to determine the amount of substance. Moles are not atoms. Thus, option B cannot be true.
• This hypothesis talks about gases of equal volume, not equal pressure. Hence, option C is false.
• Option D is fully incorrect because it does not match with two aspects of the actual hypothesis, that is equal pressure (should be equal volume) and moles (should be atoms).
  Hence, option A is the correct answer to this question.

Note: Many students make mistakes between moles and atoms. It has already been mentioned that moles are the fundamental standard in chemistry which are used to determine the amount of substance. Atoms are the particles in the elements. Hence, this difference should be kept in mind while selecting an answer.