Advertisements
Advertisements
Question
The mass of one molecule of a substance is 4.65 × 10–23 g. What is its molecular mass ? What could this substance be ?
Advertisements
Solution
Given:
Mass of one molecule of a substance = 4.65 × 10-23
We know that the mass of a molecule of a substance is equal to the mass of 1 mole of that substance. 1 mole of a substance consists of 6.022 × 1023 molecules; therefore, the mass of a molecule of a substance is equal to the mass of 6.022 × 1023 molecules.
Therefore, to calculate the molecular mass of the substance, we need to calculate the mass of 6.022 × 1023 molecules of that substance.
Mass of 1 molecule of the substance = 4.65 × 10-23
Mass of 6.022 × 1023 molecules of the substance = 6.022 × 1023 × 4.65 × 10-23 = 28g
Hence, molecular mass of the substance is 28 u.
Nitrogen has a molecular mass of 28 u; therefore, the substance is nitrogen.
APPEARS IN
RELATED QUESTIONS
Calculate the molecular mass of H2.
The molecular formula of glucose is C6H12O6. Calculate its molecular mass. (Atomic masses : C = 12 u ; H = 1 u ; O = 16 u)
Calculate the molecular mass of hydrogen bromide (HBr). (Atomic masses : H = 1 u ; Br = 80 u)
Calculate the molecular masses of the following compounds :
Hydrogen sulphide, H2S
Define gram molecular mass of a substance. How much is the gram molecular mass of oxygen ?
Calculate:
The gram molecular mass of chlorine if 308cm3 of it at STP weighs 0.979 g.
Calculate:
The volume of 4g of H2 at 4 atmosphere.
An unknown gas shows a density of 3 g per litre at 273°C and 1140 mm Hg pressure. What is the gram molecular mass of this gas?
Urea [CO(NH2)2] is an important nitrogenous fertilizer. Urea is sold in 50 kg sacks. What mass of nitrogen is in one sack of urea?
The formula unit mass of Ca3 (PO4)2 is ————.
