Understanding Temporary Hardness

Oct 13, 2025 by wbrum.org 46 views

**The Temporary Hardness (in ppm of CaCO3) when 50L of Hard Water Requires 11.2g of Quick Lime for Removing Hardness is X. The Value of X/100 is?**

Understanding Temporary Hardness

Temporary hardness, also known as carbonate hardness, is a type of water hardness that can be removed by boiling or adding a chemical treatment, such as quick lime (calcium oxide). It is caused by the presence of dissolved calcium and magnesium bicarbonates in the water.

Calculating Temporary Hardness

To calculate the temporary hardness of water, we need to know the amount of quick lime required to remove the hardness. In this case, 11.2g of quick lime is required to remove the hardness from 50L of hard water.

Step 1: Calculate the Number of Moles of Quick Lime

The molar mass of calcium oxide (CaO) is 56.08g/mol. We can calculate the number of moles of quick lime required as follows:

moles_of_quick_lime = mass_of_quick_lime / molar_mass_of_quick_lime
moles_of_quick_lime = 11.2g / 56.08g/mol
moles_of_quick_lime = 0.2 mol

Step 2: Calculate the Number of Moles of Calcium Bicarbonate

The molar mass of calcium bicarbonate (Ca(HCO3)2) is 162.14g/mol. We can calculate the number of moles of calcium bicarbonate that can be removed by the quick lime as follows:

moles_of_calcium_bicarbonate = moles_of_quick_lime * 2
moles_of_calcium_bicarbonate = 0.2 mol * 2
moles_of_calcium_bicarbonate = 0.4 mol

Step 3: Calculate the Mass of Calcium Bicarbonate

We can calculate the mass of calcium bicarbonate that can be removed by the quick lime as follows:

mass_of_calcium_bicarbonate = moles_of_calcium_bicarbonate * molar_mass_of_calcium_bicarbonate
mass_of_calcium_bicarbonate = 0.4 mol * 162.14g/mol
mass_of_calcium_bicarbonate = 65.256g

Step 4: Calculate the Concentration of Calcium Bicarbonate

We can calculate the concentration of calcium bicarbonate in the water as follows:

concentration_of_calcium_bicarbonate = mass_of_calcium_bicarbonate / volume_of_water
concentration_of_calcium_bicarbonate = 65.256g / 50L
concentration_of_calcium_bicarbonate = 1.30512g/L

Step 5: Calculate the Temporary Hardness

We can calculate the temporary hardness of the water as follows:

temporary_hardness = concentration_of_calcium_bicarbonate * 1000
temporary_hardness = 1.30512g/L * 1000
temporary_hardness = 1305.12 ppm

The Value of X/100 is?

The value of X/100 is 13.0512.

Q&A

Q: What is temporary hardness?

A: Temporary hardness, also known as carbonate hardness, is a type of water hardness that can be removed by boiling or adding a chemical treatment, such as quick lime (calcium oxide).

Q: How is temporary hardness calculated?

A: Temporary hardness is calculated by determining the amount of quick lime required to remove the hardness from a given volume of water.

Q: What is the molar mass of calcium oxide (CaO)?

A: The molar mass of calcium oxide (CaO) is 56.08g/mol.

Q: What is the molar mass of calcium bicarbonate (Ca(HCO3)2)?

A: The molar mass of calcium bicarbonate (Ca(HCO3)2) is 162.14g/mol.

Q: How is the number of moles of quick lime calculated?

A: The number of moles of quick lime is calculated by dividing the mass of quick lime by its molar mass.

Q: How is the number of moles of calcium bicarbonate calculated?

A: The number of moles of calcium bicarbonate is calculated by multiplying the number of moles of quick lime by 2.

Q: How is the mass of calcium bicarbonate calculated?

A: The mass of calcium bicarbonate is calculated by multiplying the number of moles of calcium bicarbonate by its molar mass.

Q: How is the concentration of calcium bicarbonate calculated?

A: The concentration of calcium bicarbonate is calculated by dividing the mass of calcium bicarbonate by the volume of water.

Q: How is the temporary hardness calculated?

A: The temporary hardness is calculated by multiplying the concentration of calcium bicarbonate by 1000.

Q: What is the value of X/100?

A: The value of X/100 is 13.0512.