Answer:
5.02 g pentane.
Explanation:
Hello,
Molality is given by:
[tex]m=\frac{mol_{solute}}{mass_{solvent}}[/tex]
Since the mass of the solvent (benzene) is 67 g, its value in kg is 0.067 kg because it is needed in that way in the formula. Now, solving for the moles of pentane (solute):
[tex]mol_{solute}=m*m_{solvent}=1.04\frac{mol}{kg_{solvent}}*0.067kg_{solvent}\\mol_{solute}=0.06968 mol[/tex]
Converting from moles to grams of pentane, we get the final answer:
[tex]M_{pentane}=12*5+12=72g/mol\\\\m_{solute}=0.06968mol*\frac{72g}{1mol} =5.02gC_5H_{12}[/tex]
Best regards.
