In the hardness calculation, what does A represent?

In the hardness calculation, what does A represent?

• A. volume of sample
• B. mL of acid used
• C. mg CaCO3 equivalent to titrant
• D. mL of titration for sample

Answer: (D)

In hardness calculations, A is the volume of titrant that actually reacts with the sample during the titration—the amount of titrant used to reach the endpoint. This value, in milliliters, is combined with the titrant’s normality and the sample’s volume in the formula Hardness (mg/L as CaCO3) = (A × N × 50,000) / B, where B is the sample volume in milliliters. The constant 50,000 converts the units to mg/L as CaCO3, reflecting how much CaCO3 equivalent hardness corresponds to the amount of titrant used. For instance, titrating 100 mL of water with a titrant of 0.02 N that required 10 mL would give hardness = (10 × 0.02 × 50,000) / 100 = 100 mg/L as CaCO3.

In hardness calculations, A is the volume of titrant that actually reacts with the sample during the titration—the amount of titrant used to reach the endpoint. This value, in milliliters, is combined with the titrant’s normality and the sample’s volume in the formula Hardness (mg/L as CaCO3) = (A × N × 50,000) / B, where B is the sample volume in milliliters. The constant 50,000 converts the units to mg/L as CaCO3, reflecting how much CaCO3 equivalent hardness corresponds to the amount of titrant used. For instance, titrating 100 mL of water with a titrant of 0.02 N that required 10 mL would give hardness = (10 × 0.02 × 50,000) / 100 = 100 mg/L as CaCO3.