relative molecular mass of 1,1-bis(3,4-dimethylphenyl)ethane

1, 1-bis(3, 4-dimethylphenyl)ethane | relative molecular mass

Find the relative molecular mass, M_r, for 1, 1-bis(3, 4-dimethylphenyl)ethane: M_r = sum _iN_im_i/m_u Plan: • Write the chemical formula and gather atomic masses from the periodic table. • Determine values for N_i and m_i using these items. • Finally, compute the mass. Write the chemical formula: [(CH_3)_2C_6H_3]_2CHCH_3 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i C (carbon) | 18 H (hydrogen) | 22 Look up the atomic mass, m_i, in unified atomic mass units, u, for each element in the periodic table. Since m_i is divided by the atomic mass constant, m_u, the result is a unitless relative atomic mass: | N_i | m_i/m_u C (carbon) | 18 | 12.011 H (hydrogen) | 22 | 1.008 Multiply N_i by m_i/m_u to compute the relative mass for each element. Then sum those values to compute the relative molecular mass, M_r: Answer: | | | N_i | m_i/m_u | relative mass C (carbon) | 18 | 12.011 | 18 × 12.011 = 216.198 H (hydrogen) | 22 | 1.008 | 22 × 1.008 = 22.176 M_r = 216.198 + 22.176 = 238.374

≈ 0.33 × relative molecular mass of fullerene ( ≈ 721 )

≈ 1.2 × relative molecular mass of caffeine ( ≈ 194 )

≈ 4.1 × relative molecular mass of sodium chloride ( ≈ 58 )

Molar mass M from M = M_uM_r: | 238 g/mol (grams per mole)

Molecular mass m from m = M_rM_u/N_A: | 4×10^-22 grams | 4×10^-25 kg (kilograms)