Question

Вычислите относительную молекулярную массу сульфида лития Li2S найдите массовые доли химических элементов для указного вещества

Answer 1

Молекулярная масса Li = 6,941, S = 32,064. Молекулярная масса Li2S = 6,941×2+32,064=45,946 г/моль. Массовая доля Li = 6,941×2×100÷45,946=30,214 %, S = 32,064×100÷45,946=69,786 %.

Answer 2

Calculation of Relative Molecular Mass of Lithium Sulfide (Li2S)

To calculate the relative molecular mass of lithium sulfide (Li2S), we need to consider the atomic masses of lithium (Li) and sulfur (S) and the number of atoms present in the compound.

The atomic mass of lithium (Li) is approximately 6.94 g/mol, and the atomic mass of sulfur (S) is approximately 32.06 g/mol.

The formula for lithium sulfide (Li2S) indicates that there are two lithium atoms and one sulfur atom in each molecule.

To calculate the relative molecular mass, we can sum up the atomic masses of each element in the compound:

Relative Molecular Mass of Li2S = (2 * Atomic Mass of Li) + Atomic Mass of S

Substituting the atomic masses:

Relative Molecular Mass of Li2S = (2 * 6.94 g/mol) + 32.06 g/mol

Calculating the values:

Relative Molecular Mass of Li2S = 13.88 g/mol + 32.06 g/mol

Relative Molecular Mass of Li2S = 45.94 g/mol

Therefore, the relative molecular mass of lithium sulfide (Li2S) is approximately 45.94 g/mol.

Mass Percentages of Elements in Lithium Sulfide (Li2S)

To find the mass percentages of the elements in lithium sulfide (Li2S), we need to calculate the mass of each element in the compound and then divide it by the total mass of the compound.

The molar mass of lithium sulfide (Li2S) is 45.94 g/mol, as calculated earlier.

To find the mass of lithium (Li) in Li2S, we multiply the molar mass of Li by the number of moles of Li in the compound (which is 2):

Mass of Li = (2 * Atomic Mass of Li) = (2 * 6.94 g/mol) = 13.88 g

To find the mass of sulfur (S) in Li2S, we multiply the molar mass of S by the number of moles of S in the compound (which is 1):

Mass of S = Atomic Mass of S = 32.06 g/mol

Now, we can calculate the mass percentages:

Mass Percentage of Li = (Mass of Li / Molar Mass of Li2S) * 100

Mass Percentage of Li = (13.88 g / 45.94 g/mol) * 100

Mass Percentage of Li ≈ 30.23%

Mass Percentage of S = (Mass of S / Molar Mass of Li2S) * 100

Mass Percentage of S = (32.06 g / 45.94 g/mol) * 100

Mass Percentage of S ≈ 69.77%

Therefore, the mass percentages of lithium (Li) and sulfur (S) in lithium sulfide (Li2S) are approximately 30.23% and 69.77%, respectively.

Please note that the values provided are approximate and may vary slightly depending on the exact atomic masses used.