Formula unit definition, (of an ionic compound that does not form molecules, as most salts) the chemical formula with the least number of elements out of the set of empirical formulas having the same proportion of ions as elements: NaCl is the formula unit for â¦ A formula unit in chemistry is the empirical formula of any ionic or covalent network solid compound used as an independent entity for stoichiometric calculations. (c) 32 g of sulphur = 1 mol. 1) The smallest repeating unit of a substance. 3. The mass and weight of an object are not the same. over Define formula unit mass - 31556982 Explanation. The mass formula is given as Mass = Ï × v. Where, Calculate formula unit mass of NaCI (Atomic mass of Na = 23 u, Cl = 35.5 u) Answer. It is related to the concept of an empirical formula, which is the simplest chemical formula expression for a non-ionic chemical compound. The unit of molar mass is kg/mol. Formula mass, or in other words relative atomic mass is the mass of an atom when compared to a standard atom, in this is Carbon-12. Significance of chemical formula - definition The chemical formula of the compound has quantitative significance. Question. Formula unit, or in other words empirical formula is the simplest ratio of atoms of each element in a compound. (a) Define atomic mass unit. = 2Na + 1C + 3O = (2 × 23) + (1 × 12) +( 3 × 16) = 46 + 12 + 48 = 106 u. A formula unit is the chemical formula representing an ionic compound in its simplest and most reduced terms. The formula unit mass of a substance is the sum of the atomic masses of all the atoms in the formula unit of an ionic compound. It is the lowest whole number ratio of ions represented in an ionic compound. Relative atomic mass of an element = the average mass of one atom of the element. Definition of formula unit. Formula unit mass of NaCI = (23 + 35.5) = 58.5 u. (b) Distinguish between molecular mass and molar mass. The formula unit mass is same as molecular mass which is equal to the sum of masses of atoms present in a formula unit. Question 10. 2. Define formula unit mass. Therefore its formula unit mass is the same as its molecular mass = 2 x 23 + 32 + 4 x 16 = 142 u (b) The mass of one mole of sulphur atoms = 32 u. When we multiply the number of moles to the molar mass, the unit 'moles' gets canceled, and we are left with the unit 'grams.' Was this definition helpful? The formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in the empirical formula. The units of formula mass âatomic mass unitâ (amu). Question. Empirical formulas reduce molecules to their simplest ratio of atoms. The molecule for nonionic substances. Answer: (a) Atomic mass unit (u) is 1/12 of the mass of one atom of C-12. 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