Question

Concentrated hydrochloric acid is made by pumping hydrogen chloride gas into distilled water. If concentrated HCl contains 439 g of HCl per liter, what is the molarity?

Short answer

The molarity of the concentrated hydrochloric acid can be calculated using the following steps: 1. Find the molar mass of HCl: Molar mass of HCl = Molar mass of H + Molar mass of Cl = 1.008 g/mol + 35.453 g/mol = 36.461 g/mol 2. Calculate the moles of HCl: moles of HCl = mass of HCl / molar mass of HCl = 439 g / 36.461 g/mol = 12.043 mol 3. Calculate the molarity: Molarity = moles of solute / volume of solution in liters = 12.043 mol / 1 L = \(12.043 M\). Therefore, the molarity of the concentrated hydrochloric acid is \(12.043 M\).

Step-by-step solution

Find the molar mass of HCl

To convert the mass of HCl to moles, we will first need to determine the molar mass of HCl. The atomic masses of hydrogen (H) and chlorine (Cl) can be found on the periodic table: Molar mass of H = 1.008 g/mol Molar mass of Cl = 35.453 g/mol The molar mass of HCl = Molar mass of H + Molar mass of Cl.

Calculate the moles of HCl

Now that we know the molar mass of HCl, we can use it to convert the given mass of HCl (439 g) to moles. Use the formula: moles of HCl = mass of HCl / molar mass of HCl

Calculate the molarity

To find the molarity, use the formula: Molarity = moles of solute / volume of solution in liters We have the moles of HCl and the volume of the solution (1 L), so we can plug these values into the formula to calculate the molarity.

Key concepts

Hydrochloric acid

Hydrochloric acid, often abbreviated as HCl, is a strong acid that is commonly used in various industrial and laboratory applications. This acid is formed by dissolving hydrogen chloride gas in water. It is known for its pungent smell and ability to dissociate completely in water to release hydrogen ions, making it a strong acid.

• Use in Laboratories: It is usually used for cleaning and refining processes due to its ability to react with metals and other compounds.
• Natural Occurrence: Hydrochloric acid is naturally found in the gastric acid in our stomachs, aiding in digestion.

Understanding how HCl is prepared and calculated in solutions is crucial for various fields of study and many practical applications.

Molar mass

Molar mass is a fundamental concept in chemistry, representing the mass of one mole of a substance. It is usually expressed in grams per mole (g/mol). To find the molar mass of a compound like hydrochloric acid, we add together the molar masses of all the atoms in the molecule. For HCl:

• The molar mass of hydrogen (H) = 1.008 g/mol.
• The molar mass of chlorine (Cl) = 35.453 g/mol.

Add these together to get the molar mass of HCl: \[Molar \ mass \ of \ HCl = 1.008 \ g/mol + 35.453 \ g/mol = 36.461 \ g/mol\]
This value will help us convert the mass of HCl to moles, which is essential for calculating the molarity of a solution.

Chemical solution

A chemical solution is a homogeneous mixture composed of two or more substances. Specifically, in our case, hydrochloric acid is a solution where the solute (hydrogen chloride) is dissolved into the solvent (water). Understanding the composition and properties of solutions is essential, especially when dealing with acids like HCl.

• Concentration: This describes how much solute is present in a given volume of solvent, often expressed as molarity, which is moles per liter.
• Preparation: Concentrated solutions such as HCl are carefully prepared to ensure the desired concentration of solute is achieved.

Recognizing how chemical solutions are prepared and measured allows chemists to precisely control reaction conditions and produce desired results.

Moles conversion

Converting between mass and moles is a key skill in chemistry. It allows chemists to understand and predict how substances will react in a chemical equation. Moles serve as a bridge between the microscopic world of atoms and the macroscopic world we observe.
For hydrochloric acid, the process to convert grams of HCl to moles involves using its molar mass:
\[\text{Moles \ of \ HCl} = \frac{\text{mass \ of \ HCl} \ (439 \,g)}{\text{molar \ mass \ of \ HCl} \ (36.461 \ g/mol)}\]
This conversion allows calculation of the concentration, or molarity, of the solution since molarity is defined as moles of solute per liter of solution. Understanding and performing these conversions is critical for tasks such as calculating reactants and products in chemical reactions.