The density of water and ethanol at room temperature is 1.0 g/mL and 0.789 g/mL respectively. What volume of ethanol contains the same number of molecules as are present in 100 mL of water?

Question

The density of water and ethanol at room temperature is 1.0 g/mL and 0.789 g/mL respectively. What volume of ethanol contains the same number of molecules as are present in 100 mL of water? (A) 307.8 mL (B) 168.7 mL (C) 323.9 mL (D) 253.3 mL

Tardigrade Admin · Accepted Answer

An equal number of moles contain equal number of molecules.

\frac{wt. of C _{2} H _{5} O H}{mol. wt. of C _{2} H _{5} O H} = \frac{wt. of H _{2} O}{mol. wt. of H _{2} O}

\frac{0.789 \times volume of C _{2} H _{5} O H}{46} = \frac{1.0 \times 100}{18}

Volume of

C_{2} H_{5} O H = \frac{100}{18} \times \frac{46}{0.789}

= 323.9 m L

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Q. The density of water and ethanol at room temperature is 1.0g/mL and 0.789g/mL respectively. What volume of ethanol contains the same number of molecules as are present in 100mL of water?

307.8 mL

168.7 mL

323.9 mL

253.3 mL

An equal number of moles contain equal number of molecules. mol. wt. of C2​H5​OH wt. of C2​H5​OH​= mol. wt. of H2​O wt. of H2​O​ 460.789× volume of C2​H5​OH​=181.0×100​ Volume of C2​H5​OH=18100​×0.78946​ =323.9mL.

Q. The density of water and ethanol at room temperature is $1.0 g / m L$ and $0.789 g / m L$ respectively. What volume of ethanol contains the same number of molecules as are present in $100 m L$ of water?