Input interpretation
![cobalt(II) chloride dihydrate | molar mass](../image_source/39bf02218116ad77c77570d3911f7e1d.png)
cobalt(II) chloride dihydrate | molar mass
Result
![Find the molar mass, M, for cobalt(II) chloride dihydrate: M = sum _iN_im_i 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: CoCl_2·2H_2O Use the chemical formula, CoCl_2·2H_2O, to count the number of atoms, N_i, for each element: | N_i Cl (chlorine) | 2 Co (cobalt) | 1 H (hydrogen) | 4 O (oxygen) | 2 Look up the atomic mass, m_i, in g·mol^(-1) for each element in the periodic table: | N_i | m_i/g·mol^(-1) Cl (chlorine) | 2 | 35.45 Co (cobalt) | 1 | 58.933194 H (hydrogen) | 4 | 1.008 O (oxygen) | 2 | 15.999 Multiply N_i by m_i to compute the mass for each element. Then sum those values to compute the molar mass, M: Answer: | | | N_i | m_i/g·mol^(-1) | mass/g·mol^(-1) Cl (chlorine) | 2 | 35.45 | 2 × 35.45 = 70.90 Co (cobalt) | 1 | 58.933194 | 1 × 58.933194 = 58.933194 H (hydrogen) | 4 | 1.008 | 4 × 1.008 = 4.032 O (oxygen) | 2 | 15.999 | 2 × 15.999 = 31.998 M = 70.90 g/mol + 58.933194 g/mol + 4.032 g/mol + 31.998 g/mol = 165.86 g/mol](../image_source/e4f3490b4803f3846c41177940628f20.png)
Find the molar mass, M, for cobalt(II) chloride dihydrate: M = sum _iN_im_i 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: CoCl_2·2H_2O Use the chemical formula, CoCl_2·2H_2O, to count the number of atoms, N_i, for each element: | N_i Cl (chlorine) | 2 Co (cobalt) | 1 H (hydrogen) | 4 O (oxygen) | 2 Look up the atomic mass, m_i, in g·mol^(-1) for each element in the periodic table: | N_i | m_i/g·mol^(-1) Cl (chlorine) | 2 | 35.45 Co (cobalt) | 1 | 58.933194 H (hydrogen) | 4 | 1.008 O (oxygen) | 2 | 15.999 Multiply N_i by m_i to compute the mass for each element. Then sum those values to compute the molar mass, M: Answer: | | | N_i | m_i/g·mol^(-1) | mass/g·mol^(-1) Cl (chlorine) | 2 | 35.45 | 2 × 35.45 = 70.90 Co (cobalt) | 1 | 58.933194 | 1 × 58.933194 = 58.933194 H (hydrogen) | 4 | 1.008 | 4 × 1.008 = 4.032 O (oxygen) | 2 | 15.999 | 2 × 15.999 = 31.998 M = 70.90 g/mol + 58.933194 g/mol + 4.032 g/mol + 31.998 g/mol = 165.86 g/mol
Unit conversion
![0.1659 kg/mol (kilograms per mole)](../image_source/10221c099c56887bd77e054fff9afb5c.png)
0.1659 kg/mol (kilograms per mole)
Comparisons
![≈ ( 0.23 ≈ 1/4 ) × molar mass of fullerene ( ≈ 721 g/mol )](../image_source/4c027bc2bc233d0bf0b40b6dca7aa9a3.png)
≈ ( 0.23 ≈ 1/4 ) × molar mass of fullerene ( ≈ 721 g/mol )
![≈ 0.85 × molar mass of caffeine ( ≈ 194 g/mol )](../image_source/dc100c9b14a9bb542fbb719f2118cdb2.png)
≈ 0.85 × molar mass of caffeine ( ≈ 194 g/mol )
![≈ 2.8 × molar mass of sodium chloride ( ≈ 58 g/mol )](../image_source/278cb8127a19719d68cef2b64d62be51.png)
≈ 2.8 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
![Mass of a molecule m from m = M/N_A: | 2.8×10^-22 grams | 2.8×10^-25 kg (kilograms) | 166 u (unified atomic mass units) | 166 Da (daltons)](../image_source/66b65c7e256e6c5d4c72b4f69e7de0be.png)
Mass of a molecule m from m = M/N_A: | 2.8×10^-22 grams | 2.8×10^-25 kg (kilograms) | 166 u (unified atomic mass units) | 166 Da (daltons)
![Relative molecular mass M_r from M_r = M_u/M: | 166](../image_source/5ceaa52d7f2e9824ee54e90ea92b4fe6.png)
Relative molecular mass M_r from M_r = M_u/M: | 166