Overview
- Hydrochloric acid is a clear colorless aqueous solution of hydrogen chloride (HCl) that can be supplied as a 37% (w/w) hydrogen chloride solution.
- 37% (w/w) hydrochloric acid means that 100 g of hydrochloric acid contains 37 g of hydrogen chloride.
- The density of 37% (w/w) hydrochloric acid is 1.2 g/ml at 25° C. This means the weight of the 1 ml of hydrochloric acid is 1.2 g at 25°C.
- Molarity refers to the number of moles of the solute present in 1 liter of solution.
- In simple words, 1 mole is equal to the atomic weight of the substance. For example, 1 mole of hydrogen chloride is equal to 36.46 g of hydrogen chloride (molecular weight = 36.46).
- Precautions: Concentrated HCl is a very strong acid that will burn your skin instantly upon contact! Wear gloves, goggles, and lab coat.
Preparation
Step 1:
Calculate the volume of 100 grams of Hydrochloric acid.
Formula:
Density = weight / volume or
Volume = weight / density
Volume of 100 gram of Hydrochloric acid = 100/1.2 = 83.33 ml
Note: 37% (w/w) Hydrochloric acid means that 100 grams of Hydrochloric acid contain 37 grams of Hydrogen chloride.
The volume of 100 grams of Hydrochloric acid is 83.33 ml. That means 37 grams of Hydrogen chloride is present in 83.33 ml of Hydrochloric acid.
Step 2:
Calculate how many grams of Hydrogen chloride is present in 1000 ml of Hydrochloric acid.
83.33 ml of Hydrochloric acid contains = 37 g of Hydrogen chloride.
1 ml of Hydrochloric acid will contain = 37/83.33 g of Hydrogen chloride.
1000 ml of Hydrochloric acid will contain = 1000 x 37/83.33 = 444.01776 g of acetic acid
1000 ml of Hydrochloric acid will contain 444.01776 g of Hydrogen chloride.
Step 3:
Calculate the number of moles of Hydrogen chloride present in 444.01776 g of Hydrogen chloride.
36.46 grams of Hydrogen chloride = 1 mole
1 gram of Hydrogen chloride = 1/36.46 moles
444.01776 grams of Hydrogen chloride = 444.01776 x 1/36.46 = 12.178 moles
Therefore, we can say that 1 liter of Hydrochloric acid contains 12.178 moles (rounded to 12.18 M) or in other words molarity of 37% (w/w) Hydrochloric acid is equal to 12.18 M.
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