Answer: 0.178 mol
Step-by-step explanation:
We can use the formula M₁V₁ = M₂V₂ to determine the moles remaining after the volume is decreased due to evaporation..
Since M₁V₁ = M₂V₂ (starting mole × starting volume = end mole × end volume)
⇒ (0.125 mol)(265 mL) = M₂ (186 mL)
33.125 mol/mL = 186 mL × M₂
⇒ M₂ = 33.125 mol/mL ÷ 186 mL
= 0.178 mol