Question

How many chloride ions are in \(2 \mathrm{~mol}\) of \(\mathrm{CaCl}_{2}\) ?

Short answer

There are \( 2.4088 \times 10^{24} \) chloride ions in 2 moles of \( \mathrm{CaCl}_{2} \).

Step-by-step solution

Determine the number of units in 2 moles

One mole of any substance contains \( 6.022 \times 10^{23} \) entities. This is known as Avogadro's number. Therefore, in 2 moles of \( \mathrm{CaCl}_{2} \), there will be \( 2 \times 6.022 \times 10^{23} = 1.2044 \times 10^{24} \) units of \( \mathrm{CaCl}_{2} \).

Determine the number of chloride ions

From the formula \( \mathrm{CaCl}_{2} \), it is clear that there are two chloride ions in each unit. So, there will be \( 1.2044 \times 10^{24} \) units \( \times 2 = 2.4088 \times 10^{24} \) chloride ions in 2 moles of \( \mathrm{CaCl}_{2} \).

Key concepts

Avogadro's Number

The concept of Avogadro's number is a fundamental cornerstone in chemistry. Simply put, Avogadro's number, usually denoted as \( 6.022 \times 10^{23} \), names the quantity of atoms, ions, or molecules in one mole of a substance. Understanding this massive number helps us bridge the gap between the atomic scale and the macro scale that we can measure in the laboratory.

For instance, if we have one mole of chloride ions, it means we have \( 6.022 \times 10^{23} \) chloride ions. This constant is crucial when converting from moles to the number of particles and back, making it a staple in chemical calculations and stoichiometry.

Mole Concept

The mole concept is a method of quantifying matter used in chemistry. A mole represents a specific number of particles, whether they're atoms, molecules, or ions, similar to how a dozen represents twelve items. This concept allows chemists to count by weighing, since weighing out one mole of a substance gives you a specific mass that contains the same number of particles as a mole of any other substance contains Avogadro's number of particles.

Relating to our exercise, when it's stated that there are '2 moles' of \(\mathrm{CaCl}_{2}\), we are referring to twice the amount of Avogadro's number of calcium chloride formula units, making calculations of particles much more tangible.

Stoichiometry

Stoichiometry is the section of chemistry that deals with the relative quantities of reactants and products in chemical reactions. It's all about the ratios and proportions of elements and compounds as they transform during chemical processes. The principles of stoichiometry apply not only to reactions but also to converting moles of a compound to moles of its constituent elements or ions.

In the case of converting 2 moles of \(\mathrm{CaCl}_{2}\) to chloride ions, stoichiometry tells us that each formula unit yields two chloride ions. Therefore, multiplying the total number of \(\mathrm{CaCl}_{2}\) units by two, we determine the overall amount of chloride ions produced.

Chemical Formula

A chemical formula, such as \(\mathrm{CaCl}_{2}\) for calcium chloride, provides vital information about the composition of a chemical compound. It indicates the elements present and their respective proportions. Breaking down the formula of \(\mathrm{CaCl}_{2}\), we understand that each molecule consists of one calcium atom and two chlorine atoms.

This insight is indispensable for calculations in our exercise, where understanding that '2' following 'Cl' in the formula means there are twice as many chloride ions as calcium ions in any sample of calcium chloride. Therefore, once we know the number of \(\mathrm{CaCl}_{2}\) units, we can simply double that number to find the total number of chloride ions.