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Ethylene glycol is used as an antifreeze in a cold cliamate Mass of ethylene glycol which should be added to `4` kg for water to prevent it from freezing at `-6^(@)C` will be (`K_(f)` for water =`1.86 K kg mol^(-1)` and molar mass of ethylene glycol =`62 g mol^(-1)`)A. `400 g`B. `800 g`C. `304.60 g`D. `204.30 g` |
Answer» Correct Answer - 2 We have `DeltaT_(f)=iK_(f)m` `=(iK_(f)W_("solute"))/(M_("solute") W_("solvent"))` Thus, `W_("solute")=(DeltaT_(f)M_("solute")W_("solvent"))/(iK_(f))` we are given `i=1` `K_(f)=1.86 K kg mol^(-1)` `DeltaT_(f)=T_(f^(0)-T_(f))=(0^(@)C)-(-6^(@)C)=6^(@)C= 6 K` `M_("solute")=62 g mol^(-1)` `W_("solvent")=4 kg` Substituting these results, we get `W_("solute")=((6 K)(62 g mol^(-1))(4 kg))/((1)(1.86 K kg mol^(-1))` `=800 g` |
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