If the density of \(\mathrm{CH}_{3} \mathrm{OH}\) is \(0.80 \mathrm{~kg} \mathrm{~L}^{-1}\), the volume of…

If the density of \(\mathrm{CH}_{3} \mathrm{OH}\) is \(0.80 \mathrm{~kg} \mathrm{~L}^{-1}\), the volume of methanol to prepare \(2.5 \mathrm{~L}\) of \(0.25 \mathrm{M}\) aqueous solution is
  1. \(25.0 \mathrm{~mL}\)
  2. \(32.0 \mathrm{~mL}\)
  3. \(45.0 \mathrm{~mL}\)
  4. \(56.0 \mathrm{~mL}\)

Solution

Since molarity, \(M=n_{2} / V\), we have Amount of \(\mathrm{CH}_{3} \mathrm{OH}\) required, \(n_{2}=M V=\left(0.25 \mathrm{~mol} \mathrm{~L}^{-1}ight)(2.5 \mathrm{~L})=0.625 \mathrm{~mol}\)
Mass of \(\mathrm{CH}_{3} \mathrm{OH}\) required, \(m_{2}=n_{2} M_{2}=(0.625 \mathrm{~mol})\left(32 \mathrm{~g} \mathrm{~mol}^{-1}ight)=20.0 \mathrm{~g}=20.0 \times 10^{-3} \mathrm{~kg}\)
Volume of \(\mathrm{CH}_{3} \mathrm{OH}\) required, \(V=\frac{m_{2}}{ho}=\frac{20.0 \times 10^{-3} \mathrm{~kg}}{0.80 \mathrm{~kg} \mathrm{~L}^{-1}}=0.025 \mathrm{~L}=25.0 \mathrm{~mL}\) ^

Asked in: JEE-TOPICTESTS-CHEMISTRY

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