In titration experiments, the titre value is the volume of titrant used to reach the endpoint. When multiple measurements are taken, the average is calculated to improve accuracy. The number of significant figures in the average must reflect the precision of the individual measurements, following the rules for significant figures in addition and division.

Step 1: List the titre values with their significant figures:

• 25.2 mL has 3 significant figures
• 25.25 mL has 4 significant figures
• 25.0 mL has 3 significant figures

Step 2: Calculate the sum: 25.2 + 25.25 + 25.0 = 75.45 mL. In addition, the result should have the same number of decimal places as the measurement with the least decimal places. Here, 25.2 and 25.0 have one decimal place, while 25.25 has two. The least is one decimal place, so the sum should be rounded to one decimal place: 75.4 mL.

Step 3: Divide the sum by the number of measurements (3) to find the average: $\frac{75.4}{3}=\mathrm{25.1333...}$ mL.

Step 4: The average should be reported with the same number of significant figures as the measurement with the least significant figures in the sum. Since the sum 75.4 has 3 significant figures (from the rounding rule in addition), and we are dividing by an exact number (3), the average should have 3 significant figures. Therefore, it is rounded to 25.1 mL.

Final Answer: The average titre value has 3 significant figures.

Related Topics and Formulae

Significant Figures Rules:

• Non-zero digits are always significant.
• Zeros between non-zero digits are significant.
• Leading zeros are not significant.
• Trailing zeros in a number with a decimal point are significant.

For Addition/Subtraction: The result should have the same number of decimal places as the measurement with the least decimal places.

For Multiplication/Division: The result should have the same number of significant figures as the measurement with the least significant figures.

Average Calculation: $\text{Average}=\frac{\text{Sum of values}}{\text{Number of values}}$ , where the number of values is an exact number and does not limit significant figures.