Formula Unit Mass Definition
Formula unit mass is the sum of the atomic masses of all the atoms represented in the chemical formula of a substance. This term is primarily used for ionic compounds, which exist as extended crystal lattices rather than discrete molecules. The formula unit represents the simplest whole-number ratio of ions in the compound.
Analyzing the Options
-
Option D: The total mass of all atoms in one formula unit of a compound
This is the correct definition. For instance, the formula unit mass of Magnesium Chloride (MgCl2) is calculated by summing the atomic mass of one Magnesium (Mg) atom and the atomic masses of two Chlorine (Cl) atoms.
Calculation: Formula Unit Mass (MgCl2) = Atomic Mass (Mg) + 2 * Atomic Mass (Cl) -
Option A: The mass of a single molecule of an element
This describes molecular mass, which applies to substances that exist as molecules (e.g., O2, H2O). -
Option B: The mass of a single atom of an element
This describes atomic mass. -
Option C: The mass of one mole of a substance
This describes molar mass, representing the mass of Avogadro's number of particles.
Based on these definitions, Option D accurately explains the term 'formula unit mass'.
Important Questions from Basic Concepts of Chemistry
Which of the following pair is correct?
I. Isotopes – different mass numbers
II. Isobars – different atomic numbers
Which of the following is a zone of a flame?
I. Dark
II. Luminous
III. Non-Luminous
Sphalerite is an ore of:
If formula of sodium salt of an anion X is \(Na_2X\) , then the formula of its aluminium salt would be
Which of the following set contains same number of molecules?
A. 1 gram O 2, 2 grams SO 2
B. 1 gram CO 2, 1 gram N 2O
C. 1 gram O 2, 1 gram O 3
