The volume of distilled water they must add to the initial solution to achieve this lower concentration is 35.5 l.
Dilution is defined as the process in which the concentration of a sample is decreased by adding more solvent. The dilution formula is given below.
C₁V₁ = C₂V₂
where C₁ = initial concentration of sample = 18.0 m
V₁ = initial volume of sample = 5.00 x 10² ml
C₂ = final concentration after dilution = 0.25 m
V₂ = total final volume after dilution
Plug in the values to the formula and solve for the final volume.
C₁V₁ = C₂V₂
(18.0 m)(5.00 x 10² ml) = (0.25 m)V₂
V₂ = 36000 ml
Subtract the initial volume from the final volume to determine the volume of water needed to add.
V of water = V₂ - V₁
V of water = 36000 ml - 5.00 x 10² ml
V of water = 35500ml = 35.5 l
Learn more about dilution here: brainly.com/question/1615979
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