How would your calculated %P2O5 value be affected if you had not used this blank solution

What procedure are you using? What blank for what? You don't provide enough information to even know what you're doing.

To accurately determine the %P2O5 value, it is important to use a blank solution in the analysis. The blank solution serves as a reference to account for any impurities or background contamination that may contribute to the measured value.

If you did not use the blank solution, the calculated %P2O5 value would likely be inaccurate because it would include the impurities or background contamination in the measurement. This would result in an overestimate of the true %P2O5 content in the sample.

Therefore, not using the blank solution can lead to an incorrect assessment of the actual %P2O5 value in the sample. It is essential to always include a blank solution to ensure accurate and reliable results.