The formula of chromium(III) chloride is CrCl3. The molar mass of chromium(III) chloride is 158.36 g/mol. The molar mass of chromium(III) chloride hexahydrate is 266.45 g/mol
The Correct Answer and Explanation is:
Here are the correct answers for the chemistry questions:
The formula of chromium(III) chloride is CrCl₃.
The molar mass of chromium(III) chloride is 158.36 g/mol .
The molar mass of chromium(III) chloride hexahydrate is 266.45 g/mol .
Here is a detailed explanation of how these answers are determined.
Determining the Chemical Formula
To find the formula for chromium(III) chloride, we must first identify the ions involved. The name “chromium(III)” indicates the element chromium (Cr). The Roman numeral (III) signifies that the chromium ion has a positive charge of 3, written as Cr³⁺. The name “chloride” refers to the ion of the element chlorine (Cl). Chlorine is in Group 17 of the periodic table and typically forms an ion with a negative charge of 1, written as Cl⁻. In an ionic compound, the total positive charge must balance the total negative charge to create a neutral molecule. To balance the +3 charge of one chromium ion, three chloride ions are needed, as 3 multiplied by -1 equals -3. This results in the chemical formula CrCl₃.
Calculating Molar Mass of Chromium(III) Chloride
The molar mass of a compound is the sum of the atomic masses of its constituent elements, as found on the periodic table. For CrCl₃, we need the atomic masses of chromium and chlorine. The atomic mass of chromium (Cr) is approximately 51.996 g/mol , and the atomic mass of chlorine (Cl) is approximately 35.453 g/mol .
The calculation is as follows:
Molar Mass of CrCl₃ = (1 × Atomic Mass of Cr) + (3 × Atomic Mass of Cl)
Molar Mass = (51.996 g/mol ) + (3 × 35.453 g/mol )
Molar Mass = 51.996 + 106.359 = 158.355 g/mol .
Rounding this value to two decimal places gives 158.36 g/mol .
Calculating Molar Mass of the Hydrate
The term “hexahydrate” indicates that six (“hexa”) water (“hydrate”) molecules are attached to each formula unit of the salt. The chemical formula for this compound is CrCl₃·6H₂O. To find its molar mass, we add the mass of the six water molecules to the molar mass of the anhydrous CrCl₃. First, we calculate the molar mass of one water molecule (H₂O). Using atomic masses for hydrogen (H ≈ 1.008 g/mol ) and oxygen (O ≈ 15.999 g/mol ), the molar mass of H₂O is about 18.015 g/mol . The total mass for six water molecules is 6 × 18.015 g/mol = 108.09 g/mol .
Finally, we add the two parts together:
Molar Mass of Hydrate = Molar Mass of CrCl₃ + Molar Mass of 6H₂O
Molar Mass = 158.355 g/mol + 108.09 g/mol = 266.445 g/mol .
Rounding to two decimal places gives the final answer of 266.45 g/mol .
