Answer:
0.00025 mole
Explanation:
The number of moles of a substance can be mathematically derived from the following formula
1. mass of substance (in grams)/molar mass of substance (in grams/mole)
2. molarity of substance (in mol/dm3) x volume of substance (in dm3)
In this case, the molarity and volume of NaOH are provided, hence, the second formula will be applicable.
2.5 mL of NaOH was used = 0.0025 dm3
Number of mole of NaOH that was used to neutralize the river water:
= 0.1 x 0.0025 = 0.00025 mole
The number of mole of NaOH used to neutralize the river water is 0.00025 mole.