Question

Calculate the molar mass of \(\mathrm{MgBr}_{2}\)

Short answer

The molar mass of \(\mathrm{MgBr}_{2}\) is 184.1 g/mol.

Step-by-step solution

Recall the atomic mass of each element

Consult the periodic table to find the atomic mass of each element: magnesium (Mg) and bromine (Br). The atomic mass is usually written below the element symbol.

Convert atomic mass to molar mass

Since the molar mass of an element is numerically equivalent to its atomic mass, we have: Molar mass of Mg = 24.3 g/mol Molar mass of Br = 79.9 g/mol

Find the molar mass of each element in the compound

Multiply the molar mass of each element by the number of atoms of that element in the chemical formula. In \(\mathrm{MgBr}_{2}\), there is 1 atom of Mg and 2 atoms of Br. Molar mass of 1 Mg = 24.3 g/mol Molar mass of 2 Br = 2 * 79.9 g/mol = 159.8 g/mol

Calculate the molar mass of \(\mathrm{MgBr}_{2}\)

Add the molar mass of Mg and Br in the compound to find the total molar mass: Molar mass of \(\mathrm{MgBr}_{2}\) = Molar mass of Mg + Molar mass of Br Molar mass of \(\mathrm{MgBr}_{2}\) = 24.3 g/mol + 159.8 g/mol = 184.1 g/mol The molar mass of \(\mathrm{MgBr}_{2}\) is 184.1 g/mol.

Key concepts

Atomic Mass

Understanding atomic mass is fundamental when trying to calculate the molar mass of a compound. But what is atomic mass? Simply put, atomic mass is the weighted average mass of an atom of an element based on its isotopes and their abundance. It is usually measured in atomic mass units (amu), where one atomic mass unit is defined as one-twelfth of the mass of a carbon-12 atom.

When you look at the periodic table, you'll find the atomic mass of an element typically listed below its chemical symbol. For instance, magnesium (Mg) has an atomic mass of about 24.3 amu, and this is a key figure in calculating the molar mass of compounds containing magnesium. When it comes to the molar mass, scientists have agreed on a convenient truth: the molar mass in grams per mole (g/mol) is numerically equal to the atomic mass in amu for any element. This makes calculations much more straightforward once you have grasped the concept of atomic mass.

Periodic Table

The periodic table is not just a chart; it's a powerful tool that organizes all known elements according to their properties. It's laid out in rows, called periods, and columns, known as groups or families. Elements are listed in order of increasing atomic number (the number of protons in an atom's nucleus).

For those endeavoring to calculate molar mass, the periodic table serves as an invaluable reference, providing essential data such as atomic mass and element symbols. As you delve into the periodic table, you'll notice that each element's atomic mass is displayed, usually below the chemical symbol. Knowing how to use this information is crucial for tasks such as calculating the molar mass of a compound. Beyond atomic mass, the periodic table offers insight into element reactivity, electronegativity, and other chemical properties, all of which are fundamental to understanding chemistry as a whole.

Chemical Formula

A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. It identifies each type of element by its chemical symbol and indicates the number of atoms of each element present in the compound. For example, in the chemical formula for magnesium bromide, \(\mathrm{MgBr}_{2}\), Mg stands for magnesium, and Br stands for bromine. The subscript '2' tells you there are two atoms of bromine for every atom of magnesium.

When calculating molar mass, the information in the chemical formula is crucial. You need to multiply the atomic mass of each element (as found in the periodic table) by the number of atoms of that element in the formula. Then, sum those values to obtain the molar mass of the entire compound. This underscores the importance of both being able to interpret a chemical formula and understanding the significance of the subscripts it uses.