25 ml of SHW containing CaCO3 1 g/L consumes 12 ml of EDTA. 25 ml of hard water consumes 8 ml of standard EDTA solution. After boiling the sample, 25 ml of the boiled hard water consumes 6 ml of standard EDTA solution. Calculate the total, permanent and temporary hardness
To calculate the total, permanent, and temporary hardness of the water sample, we need to understand some concepts and equations.
1. Total Hardness: It represents the total concentration of calcium (Ca2+) and magnesium (Mg2+) ions in the water. It is expressed in terms of the equivalent calcium carbonate (CaCO3). The equation to calculate total hardness is:
Total Hardness (TH, mg/L) = (Volume of EDTA used for water sample - Volume of EDTA used for blank solution) * EDTA titer * 1000 / Volume of water sample
In this case, the blank solution is the SHW without any CaCO3, and the EDTA titer is the concentration of the standard EDTA solution used.
2. Permanent Hardness: It represents the concentration of calcium and magnesium ions that form insoluble compounds. It cannot be removed by boiling the water. The equation to calculate permanent hardness is:
Permanent Hardness (PH, mg/L) = (Volume of EDTA used for boiled water sample - Volume of EDTA used for blank solution) * EDTA titer * 1000 / Volume of water sample
3. Temporary Hardness: It represents the concentration of calcium and magnesium ions that form soluble compounds. It can be removed by boiling the water. The equation to calculate temporary hardness is:
Temporary Hardness (THard, mg/L) = Total Hardness (TH) - Permanent Hardness (PH)
Let's calculate the values using the given data:
1. Calculate the Total Hardness (TH):
Volume of EDTA used for SHW = 12 ml
Volume of EDTA used for blank solution = 0 ml (SHW without CaCO3)
EDTA titer = concentration of standard EDTA solution
Volume of water sample = 25 ml
TH = (12 ml - 0 ml) * EDTA titer * 1000 / 25 ml
2. Calculate the Permanent Hardness (PH):
Volume of EDTA used for boiled water sample = 6 ml
Volume of EDTA used for blank solution = 0 ml (boiled water without CaCO3)
EDTA titer = concentration of standard EDTA solution
Volume of water sample = 25 ml
PH = (6 ml - 0 ml) * EDTA titer * 1000 / 25 ml
3. Calculate the Temporary Hardness (THard):
THard = TH - PH
Now, by obtaining the values of TH, PH, and THard, we can calculate the total, permanent, and temporary hardness of the water sample.