can someone help me with this please? i've been stuck on this one forever...
A solution is made by mixing 25.0 mL of toluene C6H5CH3d=0867gmL with 135.0 mL of benzene C6H6d=0874gmL. Assuming that the volumes add upon mixing, the molarity (M) and molality (m) of the toluene are
M and m.
I don't see a decimal in the density tabulations. That may be your first problem. The density of toluene is 0.867 that of benzene is 0.879 g/mL.
First, let's do some housekeeping.
mass toluene = 25.0 mL x 0.867 g/mL = 21.675 g
moles toluene = 21.675/92.14 = 0.235 moles.
mass benzene = 135.0 mL x 0.874 g/mL = 117.99 g
molality = moles solute/kg solvent
0.235/0.11799 = ??m, then round to 3 significant figures.
molarity = moles solute/L soln
0.235/(0.0250 + 0.1350) = 0.235/?? = xxM, then round to three s.f.
Check my work.
To find the molarity (M) and molality (m) of toluene in the given solution, we need to use the given volumes and densities of toluene and benzene.
First, let's calculate the moles of toluene:
Moles of toluene = volume of toluene (in liters) * density of toluene (in g/mL) * molar mass of toluene
Given:
Volume of toluene = 25.0 mL = 0.025 L (since 1 L = 1000 mL)
Density of toluene = 0.867 g/mL
Molar mass of toluene: You can find the molar mass of toluene by summing up the atomic masses of its constituent elements. Carbon (C) has an atomic mass of 12.01 g/mol, and hydrogen (H) has an atomic mass of 1.01 g/mol. Toluene has 7 carbon atoms and 8 hydrogen atoms.
Molar mass of toluene = (7 * atomic mass of carbon) + (8 * atomic mass of hydrogen)
Next, let's calculate the moles of benzene:
Moles of benzene = volume of benzene (in liters) * density of benzene (in g/mL) * molar mass of benzene
Given:
Volume of benzene = 135.0 mL = 0.135 L
Density of benzene = 0.874 g/mL
Molar mass of benzene = (6 * atomic mass of carbon) + (6 * atomic mass of hydrogen)
Finally, we can calculate the molarity (M) and molality (m) of toluene:
Molarity (M) of toluene = Moles of toluene / Total volume of solution (in liters)
Molality (m) of toluene = Moles of toluene / Mass of solvent (in kg)
To find the mass of the solvent, we need to know the mass of benzene. We can calculate it using the formula:
Mass of benzene = Volume of benzene (in liters) * Density of benzene (in g/mL)
After finding the moles of toluene, moles of benzene, and the mass of the solvent, substitute these values into the formulas above to calculate the molarity (M) and molality (m) of toluene.