# Determination of Unknown Solution Concentration from Graphs or Equations

## Determination of Unknown Solution Concentration from Graphs or Equations

Section 1: Preparation and Calibration

• Establish a standard curve or calibration curve using solutions with known concentration.
• Plot concentration of the solution along the X-axis and the value of an easy-measurable quantity along the Y-axis.
• Obtain the line of best fit by drawing a straight line that passes as close as possible to each point in the graph.

Section 2: Measurement and Record

• Measure the same quantity in the unknown solution that you’ve measured in the known solutions.
• Record the measurement accurately to ensure the accuracy of the concentration determination.

Section 3: Using the Calibration Curve

• Locate the value you have measured on the Y-axis of the graph.
• Draw a line horizontally from this point until it crosses the line of best fit.

• From where the horizontal line crosses the line of best fit, drop a vertical line down to the X-axis.
• The value on the X-axis at the point where the vertical line hits is the concentration of the unknown solution.

Section 5: Use of Equations

• The equation of the line of best fit from the calibration curve can also be used to find the unknown concentration.
• Substitute the measured value into the equation to solve for concentration (x).

Section 6: Checking Accuracy

• Validate your result by performing multiple measures and then calculate the mean concentration (average).
• Compare results to the known concentration if available for self-validation.

Section 7: Safety Considerations

• When handling unknown solutions, appropriate safety precautions should be taken including use of gloves, eye protection and lab coat.
• Clean up spills immediately and dispose of waste properly.

Section 8: Communication and Documentation

• Record all experimental setup, methods, measurements, and calculations.
• Create a well-defined report following standard scientific structure.

Section 9: Potential Sources of Error

• Possible errors could stem from incorrect calibration, improper measurement, or inaccurate measurements due to equipment malfunction or user error.
• Careful monitoring, correct handling, and suitable equipment maintenance can minimise these errors.
• Always double-check measurements and calculations.