# OVERVIEW

- A 70% (w/w) Perchloric acid is a clear colorless aqueous solution of HClO
_{4}. It can be purchased from many commercial suppliers. - % refers to solution concentration in percentage and “(w/w)” refers to solute and solution amount given in grams (i.e., percent by weight). This means a 70% (w/w) Perchloric acid solution contains 70 g of HCLO
_{4}per 100 g of solution. - The density of 70% Perchloric acid solution is 1.68 g/ml at 25° C. This means the weight of the 1 ml of 70% Perchloric acid solution is 1.68 grams at 25°C.
- Molarity refers to the number of moles of the solute present in 1 litre of solution. To calculate the molarity of 70% Perchloric acid solution, you need to know how many moles of HClO
_{4}are present in 1 liter of solution. - In simple words, 1 mole is equal to the molecular weight of the substance. For example, 1 mole of HCLO
_{4}is equal to 100.46 grams of HCLO_{4}(molecular weight = 100.46).

**Calculation procedure**

Known values | |

Density of Perchloric acid | 1.68 g/ml |

Molecular weight of HCLO_{4} | 100.46 g/mole |

Concentration of Perchloric acid | 70% (% by mass, wt/wt) |

**Step 1: ****Calculate the volume of 100 grams of 70% Perchloric acid solution.**

Formula:

**Calculate the volume of 100 grams of 70% Perchloric acid solution.**

Density = $\frac{Weight}{Volume}$

OR

Volume = $\frac{\mathrm{Weight}}{\mathrm{Density}}$

The volume of 100 g of 70% Perchloric acid solution : $\frac{100}{1.68}$ = 59.5238 ml

Note: A 70% (w/w) Perchloric acid means 100 grams of solution contains 70 grams of HCLO_{4}.

The volume of 100 grams of 70% Perchloric acid solution is 59.5238 ml. This means 70 grams of HCLO_{4} is present in 59.5238 ml of 70% Perchloric acid solution.

**Step 2: ****Calculate how many grams of HCLO**_{4}** is present in 1000 ml of 70% Perchloric acid solution.**

**Calculate how many grams of HCLO**

_{4}

**is present in 1000 ml of 70% Perchloric acid solution.**

59.5238 ml of 70% Perchloric acid solution contains = 70 grams of HClO_{4}

1 ml of 70% Perchloric acid solution will contain = $\frac{70}{59.5238}$ grams of HClO_{4}

1000 ml of 70% Perchloric acid solution will contain = $\frac{1000x70}{59.5238}$ = 1176.00 grams of HClO_{4}

1000 ml of 70% Perchloric acid solution will contain 1176.00 grams of HCLO_{4}.

**Step 3: ****Calculate the number of moles of HCLO4 present in 1176.00 grams of HCLO4**.

**Calculate the number of moles of HCLO4 present in 1176.00 grams of HCLO4**.

100.46 g of HClO_{4} is equal to 1 mole.

1 g of HClO_{4} will be equal to $\frac{1}{100.46}$ moles.

1176.00 grams of HCLO_{4} will be equal to = $\frac{1176.00\mathrm{x}1}{100.46}$ = 11.706 moles

Therefore, we can say that 1 liter of 70% Perchloric acid solution contains 11.706 moles of HClO4 or in other words molarity of 70% (w/w) Perchloric acid is equal to 11.706M.

**Calculator – Calculate the molarity of concentrated Perchloric acid (HClO**_{4})

_{4})

_{4}) when concentration is given in % by mass (w/w)

**HClO _{4} Molar Mass:** 100.46 g/mole

**Concentration of Perchloric acid solution:**% (w/w)

(Change the % (w/w) concentration)

**Density of Perchloric acid solution:** g/ml

(Change the density)

**Molarity of Perchloric acid solution:** 11.706 M

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