Question

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A student dissolves 0.250 mol NaC1 in 2.05 kg H20. What is the molality of the resulting solution? Show your work.

Answer 1

• No of moles of solute(NaCl)=0.250mol
• Mass of solvent (water) in kg=2.05kg

`\\ \rm\Rrightarrow Molality=(Moles\:of\:solute)/(Mass\:of\: solvent\:in\:kg)`

`\\ \rm\Rrightarrow Molality=0.250/2.05`

`\\ \rm\Rrightarrow Molality=0.1m`

Answer 2

m = 0.122 m

Step-by-step explanation:

Molality(m): A measure of the number of moles of solute in a solution corresponding to 1 kg or 1000 g of solvent.

`\mathrm{Molality\:Formula}:\quad \mathrm m = ( mole\:of\:solute )/( mass\:of\:solvent\:in\:kg )`

`\mathrm m = ( mole)/( kg )`

`\mathrm{Substitute\:the\:numbers\:into\:the\:`

`\mathrm m = ( 0.250 )/( 2.05 )`

`\mathrm{Divide\:0.250\:by\:2.05\:and\:get\:0.12195122}`

`\mathrm m = {0.12195122}`

`\mathrm{Round\:to\:the\:nearest\:thousandths\:place}`

`\mathrm m = 0.122`