Input interpretation
![potassium dihydrogen arsenate | molar mass](../image_source/cdbb07c8aae23e4a7a80b6c61d9ce8d8.png)
potassium dihydrogen arsenate | molar mass
Result
![Find the molar mass, M, for potassium dihydrogen arsenate: 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: KH_2AsO_4 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i As (arsenic) | 1 H (hydrogen) | 2 K (potassium) | 1 O (oxygen) | 4 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) As (arsenic) | 1 | 74.921595 H (hydrogen) | 2 | 1.008 K (potassium) | 1 | 39.0983 O (oxygen) | 4 | 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) As (arsenic) | 1 | 74.921595 | 1 × 74.921595 = 74.921595 H (hydrogen) | 2 | 1.008 | 2 × 1.008 = 2.016 K (potassium) | 1 | 39.0983 | 1 × 39.0983 = 39.0983 O (oxygen) | 4 | 15.999 | 4 × 15.999 = 63.996 M = 74.921595 g/mol + 2.016 g/mol + 39.0983 g/mol + 63.996 g/mol = 180.032 g/mol](../image_source/ba1b3b723b9ac5652812370fe5ea01de.png)
Find the molar mass, M, for potassium dihydrogen arsenate: 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: KH_2AsO_4 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i As (arsenic) | 1 H (hydrogen) | 2 K (potassium) | 1 O (oxygen) | 4 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) As (arsenic) | 1 | 74.921595 H (hydrogen) | 2 | 1.008 K (potassium) | 1 | 39.0983 O (oxygen) | 4 | 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) As (arsenic) | 1 | 74.921595 | 1 × 74.921595 = 74.921595 H (hydrogen) | 2 | 1.008 | 2 × 1.008 = 2.016 K (potassium) | 1 | 39.0983 | 1 × 39.0983 = 39.0983 O (oxygen) | 4 | 15.999 | 4 × 15.999 = 63.996 M = 74.921595 g/mol + 2.016 g/mol + 39.0983 g/mol + 63.996 g/mol = 180.032 g/mol
Unit conversion
![0.18003 kg/mol (kilograms per mole)](../image_source/212ba00b3a484e5084e20db533dbbc57.png)
0.18003 kg/mol (kilograms per mole)
Comparisons
![≈ ( 0.25 ≈ 1/4 ) × molar mass of fullerene ( ≈ 721 g/mol )](../image_source/3970ab47e75096dde7bb9906c6efaa0b.png)
≈ ( 0.25 ≈ 1/4 ) × molar mass of fullerene ( ≈ 721 g/mol )
![≈ 0.93 × molar mass of caffeine ( ≈ 194 g/mol )](../image_source/2121a8e67daed12c764981e2bc6fae8e.png)
≈ 0.93 × molar mass of caffeine ( ≈ 194 g/mol )
![≈ 3.1 × molar mass of sodium chloride ( ≈ 58 g/mol )](../image_source/5cfb249d75f7a49f55f91e7aa7406ede.png)
≈ 3.1 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
![Mass of a molecule m from m = M/N_A: | 3×10^-22 grams | 3×10^-25 kg (kilograms) | 180 u (unified atomic mass units) | 180 Da (daltons)](../image_source/ccd1dceb132642b78debdca1512f1cb4.png)
Mass of a molecule m from m = M/N_A: | 3×10^-22 grams | 3×10^-25 kg (kilograms) | 180 u (unified atomic mass units) | 180 Da (daltons)
![Relative molecular mass M_r from M_r = M_u/M: | 180](../image_source/aba56047094fd6393b6bce775258537e.png)
Relative molecular mass M_r from M_r = M_u/M: | 180