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Molar mass is a key concept in chemistry that helps you convert grams of a substance to moles, which are more universal for chemical equations. The molar mass is the weight of one mole of a substance, usually measured in grams per mole \( ext{(g/mol)}\).Here's how it works:

• The molar mass of an element is its atomic weight from the periodic table.
• If you're dealing with a compound, add up the atomic weights of all the atoms in the formula.

In our exercise, you're given scandium with a mass of 2.25 grams. To convert this into moles, you'd divide by the molar mass of scandium, which is 44.96 g/mol. Likewise, for hydrogen, you have a mass of 0.1502 grams and a molar mass of 1.01 g/mol.Calculating these gets you the moles necessary to solve the problem:- Scandium: \(\dfrac{2.25 \, ext{g}}{44.96 \, \text{g/mol}} = 0.0500 \, \text{moles}\)- Hydrogen: \(\dfrac{0.1502 \, \text{g}}{1.01 \, \text{g/mol}} = 0.149 \, \text{moles}\)Understanding molar mass helps in determining how much of each element you have in a chemical reaction.

An empirical formula gives the simplest whole-number ratio of the atoms in a compound. It doesn't necessarily provide the precise number of atoms as they exist in the molecule (like a molecular formula does), but it opens the door to a deeper understanding of a compound's composition.To derive an empirical formula, you generally start by converting the mass of each element to moles, which you already have from the molar mass calculations. Then, you divide all the mole values by the smallest number of moles among them. This simplifies the ratios into whole numbers, which are then used as subscripts in the formula.In your problem: - After converting to moles, the next step is to compare scandium (0.0500 moles) and hydrogen (0.149 moles).- Dividing these by the smallest number of moles (0.0500 moles for scandium), will give you a simplified mole ratio of \(1:2.98\), which rounds to \(1:3\).This rounding leads to the empirical formula ScCl₃, indicating the simplest ratio of scandium to chloride based on the reaction data provided.

Mole ratios are crucial for understanding how substances react with one another in a chemical reaction. These ratios tell you the relationship between the amounts of reactants and products involved. In essence, they serve as a chemical recipe.To find the mole ratio, you look at the balanced chemical reaction equation or deduce it from experimental data by comparing the moles calculated from the molar mass of the reactants or products.In the given scenario:

• You start with moles from your molar mass calculations: 0.0500 moles of scandium and 0.149 moles of hydrogen.
• Dividing through by the smallest value, you discern a ratio of \(1:2.98\), which rounds to \(1:3\).

This implies one scandium atom pairs with three chloride atoms since each hydrogen atom represents a chloride in the formation of ScCl₃. Mole ratios like this dictate the stoichiometry of a reaction, allowing you to predict quantities of unknowns from knowns within complex chemical reactions.