a sample of 15.00 g of an unkown metal chloride, MCl2 is dissolved in 75.0 mL water. the boiling point of the resulting solution is measured at 102.37 degrees C. what is the identity of the metal M.
I assume MCl2 is an ionic chloride so i, the van't Hoff factor, is 3.
delta T = i*Kb*m
You know delta T, Kb, and i (= 3). Solve for molality, m.
Then m = mols/kg solvent.
You know kg solvent and m, solve for mols.
Then mols = grams/molar mass
You know mols and grams, solve for molar mass.
Finally, knowing molar mass MCl2 and subtrating 2*Cl, you get atomic mass M. Identify that form the periodic table.
what's the T Kb what would the molality be plugged in for the equation
delta T = 102.37-100 = ?
i = 3
Kb = 0.512
m = ?
m= 75 mL of water 0.001kg water= o.o75 of warer.
2.37 c = 3*0.512 c/m*m
m=1.54297
to get moles
1.59297*0.075/1=0.119473 mol
molar mass
15/ 0.119473= 125.551
125.551g -2* 35.45= 54.6514 making it manganese chloride would that be correct ?
Close but I think you have a math error.
Here is your work.
m= 75 mL of water 0.001kg water= o.o75 of warer.
2.37 c = 3*0.512 c/m*m
m=1.54297
You are ok to here
to get moles
1.59297*0.075/1=0.119473 mol
I think you mistyped (transferred from the step above incorrectly) which makes the mols slightly out of place. That makes the final answer not quite right. The procedure looks ok though; therefore, I think you will be ok if you go back through and correct thos steps. I think the final answer comes out closer to Ni than Mn but check that out.
molar mass
15/ 0.119473= 125.551
125.551g -2* 35.45= 54.6514 making it manganese chloride would that be correct ?
To determine the identity of the metal M in the unknown metal chloride (MCl2), you can use the concept of boiling point elevation, which is a colligative property of solutions. Boiling point elevation occurs when a solute is dissolved in a solvent, resulting in an increase in the boiling point of the solvent.
To calculate the identity of the metal M, you need to compare the experimental boiling point elevation to the expected boiling point elevation for a known solute concentration. The formula for boiling point elevation is:
ΔTb = Kbp * m
Where:
ΔTb = change in boiling point
Kbp = boiling point elevation constant for the solvent
m = molality of the solute (moles of solute per kg of solvent)
In this case, the unknown metal chloride (MCl2) is the solute, and water is the solvent.
First, let's calculate the molality (m) of the solute:
Molar mass of MCl2 = molar mass of M + 2 * molar mass of Cl = M + 2 * 35.453 g/mol = M + 70.906 g/mol
Molality (m) = moles of solute / mass of solvent (in kg)
Mass of solvent = 75.0 mL = 0.075 L
Mass of solvent in kg = 0.075 kg
moles of solute = mass of solute / molar mass of solute
moles of solute = 15.00 g / (M + 70.906 g/mol)
Now, let's calculate the change in boiling point (ΔTb):
ΔTb = 102.37°C - 100.00°C = 2.37°C (Remember to convert to Kelvin by adding 273.15, so 2.37°C = 275.52 K)
Next, we need to find the boiling point elevation constant (Kbp) for water. For water, the Kbp is approximately 0.512 °C/m.
Finally, let's rearrange the formula to solve for the identity of the metal M:
M = (ΔTb / (Kbp * m)) - 70.906 g/mol
Now substitute the values into the formula and solve for M.
Please note that this is a simplified explanation, and additional factors may need to be considered in real-world scenarios.