Question

Water hardness experiment (Chemistry)

1. What color will the solution in the flask be when you begin the titration? What color will be present at the endpoint of the titration?

2. Given the equation below, (in the form y = mx + b) identify the y variable, the x variable, the slope and the y-intercept.

volume EDTA (in mL) = 0.0987 × concentration of Ca2+ (in ppm) + 0.6018

Answer 1

1. The color of the solution in the flask be when you begin the titration will be Colorless as in water hardness experiment the indicator use is Erichrome Black T (EBT) and therefore, the color present at the endpoint of the titration will be appearance of blue color.

2. y = mx + b

Volume EDTA (in mL) = 0.0987 × concentration of Ca2+ (in ppm) + 0.6018

Therefore, y = Volume of EDTA (in mL)

m = slope = 0.0987

x = Concentration of Ca²⁺ (in ppm)

y-Intercept = 0.6018