Final answer:
The chemist should pour out 2400 mL of the barium chlorate stock solution.
Step-by-step explanation:
To calculate the volume of the barium chlorate stock solution that the chemist should pour out, we need to use the dilution formula: C1V1 = C2V2. Given that the stock solution concentration is 0.0125 mol/L and the final volume is 300 mL, we can rearrange the formula to solve for V1:
V1 = (C2V2) / C1
Substituting the values:
V1 = (10.0 mmol/L * 300 mL) / 0.0125 mol/L = 2400 mL
Therefore, the chemist should pour out 2400 mL of the barium chlorate stock solution.