Question

If avogadro number $N_A$, is changed from ${6.022 \times 10^{23} \, mol^{-1} }$ to ${6.022 \times 10^{20} \, mol^{-1} }$ , this would change :

• A. the ratio of chemical species to each other in a balanced equation
• B. the ratio of elements to each other in a compound
• C. the definition of mass in units of grams
• D. the mass of one mole of carbon

Answer 1

The Correct Option is D

The question pertains to the concept of Avogadro's number and its impact on various chemical properties. Let's analyze the given options one by one.

1. Option 1: The ratio of chemical species to each other in a balanced equation

   The ratio of chemical species in a balanced chemical equation is determined by the stoichiometry of the reaction, which depends on the relative number of moles of reactants and products. Changing the value of Avogadro's number doesn't affect this stoichiometry, as it remains consistent irrespective of how many entities are present in one mole.

2. Option 2: The ratio of elements to each other in a compound

   In a given compound, the ratio of elements is defined by the molecular or empirical formula and remains unchanged. The chemical identity and the proportional composition of elements do not depend on the number of entities per mole, hence changing Avogadro's number does not impact this ratio.

3. Option 3: The definition of mass in units of grams

   The definition of mass units such as grams is a fundamental constant and part of the International System of Units (SI). It remains independent from Avogadro's number. Therefore, altering Avogadro's number does not redefine the unit of mass, which is grams.

4. Option 4: The mass of one mole of carbon

   Avogadro's number defines the number of atoms or molecules in one mole of a substance. If Avogadro's number is changed from \(6.022 \times 10^{23} \, \text{mol}^{-1}\) to \(6.022 \times 10^{20} \, \text{mol}^{-1}\), the absolute amount of substance that makes up one mole changes. Since one mole of carbon is traditionally defined as containing \(6.022 \times 10^{23}\) atoms, if this number changes, the mass which represents one mole of carbon also changes, because the number of carbon atoms constituting a mole is reduced by a factor of \(10^3\), thus altering the molar mass.

Therefore, the correct answer is Option 4: The mass of one mole of carbon. Changes in Avogadro's number would directly affect the molar mass calculations.