Input interpretation
![nickel(II) chloride | relative molecular mass](../image_source/5cefdd7c857a515054b193d896743c04.png)
nickel(II) chloride | relative molecular mass
Result
![Find the relative molecular mass, M_r, for nickel(II) chloride: 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: NiCl_2 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i Cl (chlorine) | 2 Ni (nickel) | 1 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 Cl (chlorine) | 2 | 35.45 Ni (nickel) | 1 | 58.6934 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 Cl (chlorine) | 2 | 35.45 | 2 × 35.45 = 70.90 Ni (nickel) | 1 | 58.6934 | 1 × 58.6934 = 58.6934 M_r = 70.90 + 58.6934 = 129.59](../image_source/13d59202589a5485cf161267370af8e3.png)
Find the relative molecular mass, M_r, for nickel(II) chloride: 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: NiCl_2 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i Cl (chlorine) | 2 Ni (nickel) | 1 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 Cl (chlorine) | 2 | 35.45 Ni (nickel) | 1 | 58.6934 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 Cl (chlorine) | 2 | 35.45 | 2 × 35.45 = 70.90 Ni (nickel) | 1 | 58.6934 | 1 × 58.6934 = 58.6934 M_r = 70.90 + 58.6934 = 129.59
Comparisons
![≈ ( 0.18 ≈ 1/6 ) × relative molecular mass of fullerene ( ≈ 721 )](../image_source/d41a595fd35046361fa82cdfea18d72d.png)
≈ ( 0.18 ≈ 1/6 ) × relative molecular mass of fullerene ( ≈ 721 )
![≈ 0.67 × relative molecular mass of caffeine ( ≈ 194 )](../image_source/f905430d199414e3386c5954a07fd618.png)
≈ 0.67 × relative molecular mass of caffeine ( ≈ 194 )
![≈ 2.2 × relative molecular mass of sodium chloride ( ≈ 58 )](../image_source/2615a4f44fbaaaf92e227d356243cb2f.png)
≈ 2.2 × relative molecular mass of sodium chloride ( ≈ 58 )
Corresponding quantities
![Molar mass M from M = M_uM_r: | 130 g/mol (grams per mole)](../image_source/8563da77ba2809588fd18a96403851ac.png)
Molar mass M from M = M_uM_r: | 130 g/mol (grams per mole)
![Molecular mass m from m = M_rM_u/N_A: | 2.2×10^-22 grams | 2.2×10^-25 kg (kilograms)](../image_source/df6dcbbb80ac5bb53cab0f2268d82743.png)
Molecular mass m from m = M_rM_u/N_A: | 2.2×10^-22 grams | 2.2×10^-25 kg (kilograms)