Final answer:
By dividing the given mass of calcium (120g) by its molar mass (40.08 g/mol), we find that the student has been given exactly 3 moles of calcium. This calculation is a basic principle of stoichiometry in chemistry, needed to quantify substances in terms of moles.
Step-by-step explanation:
The student has provided 120 grams of calcium and has asked how many moles of calcium this equates to. To calculate the number of moles, one would use the molar mass of calcium, which is approximately 40.08 grams per mole (g/mol). The calculation for the number of moles is as follows:
Number of moles = Mass (g) / Molar mass (g/mol)
For the given 120g of calcium, the calculation would be:
Number of moles = 120g / 40.08 g/mol
This simplifies to exactly 3 moles of calcium.
To add some context with a similar example given in the reference information, if you were to calculate the mass of calcium chloride (CaCl₂) with a molar mass of 110.98 g/mol for a given number of moles, you would multiply the number of moles by the molar mass. For instance, for 3.00 moles of CaCl₂, the calculation would be:
Mass = Number of moles × Molar mass
Mass = 3.00 moles × 110.98 g/mol = 332.94 grams of CaCl₂
Understanding how to convert grams to moles is a fundamental skill in chemistry, which allows for the quantification and comparison of different substances based on their molar amounts.