One mole of a compound M(HCO3)2 has a mass of 162g. Calculate the relative atomic mass of M. [H = 1, C =12, O = 16]
Answer Details
The formula of the given compound is M(HCO3)2. The total mass of the compound is 162g per mole. We need to find the relative atomic mass of M. Let the relative atomic mass of M be x. The molecular weight of the compound will then be: Molecular weight = mass of 1 mole of the compound Molecular weight = 162g/mol The molecular weight can also be calculated as the sum of the atomic weights of all the atoms in the compound. The compound has 2 H atoms, 2 C atoms, and 6 O atoms. Using the atomic weights of H, C, and O as given in the question, we get: Molecular weight = 2x + 2(12) + 6(16) Molecular weight = 2x + 120 + 96 Molecular weight = 2x + 216 We can now equate the two expressions for the molecular weight to get: 2x + 216 = 162 2x = 162 - 216 2x = -54 x = -27 This is a non-sensical value for the relative atomic mass. The reason for this is that we made an error in the calculation. The actual molecular weight of the compound should be: Molecular weight = 2x + 2(1) + 2(12) + 6(16) Molecular weight = 2x + 122 Equating the two expressions for the molecular weight gives: 2x + 122 = 162 2x = 162 - 122 2x = 40 x = 20 Therefore, the relative atomic mass of M is 20. Answer: 40