📌 Quick Answer
The molar mass of HCl (hydrogen chloride) is 36.46 g/mol.
It is found by adding the atomic mass of hydrogen (1.008 g/mol) and chlorine (35.45 g/mol): 1.008 + 35.45 = 36.46 g/mol.
🔹 Key Takeaways
- Molar mass of HCl = 36.46 g/mol (often rounded to 36.5).
- Calculated as H (1.008) + Cl (35.45).
- 1 mole of HCl contains 6.022 × 1023 molecules.
- Used to convert between grams and moles of hydrochloric acid in chemistry calculations.
What Is the Molar Mass of HCl?
The molar mass of a substance is the mass of one mole of it, expressed in grams per mole (g/mol). For hydrogen chloride (HCl) — the gas that forms hydrochloric acid when dissolved in water — the molar mass is 36.46 g/mol.
How to Calculate the Molar Mass of HCl
HCl contains one hydrogen atom and one chlorine atom. Add the standard atomic masses of each element:
| Element | Atoms | Atomic mass (g/mol) | Total |
|---|---|---|---|
| Hydrogen (H) | 1 | 1.008 | 1.008 |
| Chlorine (Cl) | 1 | 35.45 | 35.45 |
| Molar mass of HCl | 36.46 g/mol | ||
Worked Example: Grams to Moles
How many moles are in 73 g of HCl? Using moles = mass / molar mass = 73 / 36.46 = 2 moles of HCl. Each mole contains 6.022 × 1023 molecules.
Worked Example: Preparing a 1 M Solution
To make 1 litre of a 1 molar (1 M) HCl solution you need 1 mole of HCl, which is 36.46 g. In practice concentrated hydrochloric acid is a liquid, so this mass is supplied by diluting the right volume of stock acid — but the molar mass is what tells you how many grams one mole weighs.
Key Properties of Hydrochloric Acid
| Property | Value |
|---|---|
| Chemical formula | HCl |
| Molar mass | 36.46 g/mol |
| Nature | Strong monoprotic acid |
| State (pure gas) | Colourless, pungent gas |
| Common form | Aqueous solution (hydrochloric acid) |
Why the Molar Mass of HCl Is Useful
The molar mass lets chemists convert between the mass and the number of moles of hydrochloric acid, which is essential for preparing solutions of a known concentration (molarity), balancing reactions and performing titrations. It is one of the most frequently used values in school and first-year chemistry calculations.
Frequently Asked Questions
What is the molar mass of HCl?
The molar mass of HCl (hydrogen chloride) is 36.46 g/mol.
How is the molar mass of HCl calculated?
By adding the atomic mass of hydrogen (1.008 g/mol) and chlorine (35.45 g/mol) to get 36.46 g/mol.
What is the molar mass of HCl rounded?
It is often rounded to 36.5 g/mol for quick calculations.
How many grams are in one mole of HCl?
One mole of HCl has a mass of 36.46 grams.
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