<span>The minimum amount of energy needed to get a chemical reaction started is called the activation energy.
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This is a guess, but I think it could be the lack of limiting factors.
what are teacher teaching you
The wt% of KOH = 45%
This implies that there is 45 g of KOH in 100 g of the solution
Density of the solution is given as 1.45 g/ml
Therefore, the volume corresponding to 100 g of the solution is
= 100 g * 1 ml /1.45 g = 68.97 ml = 0.069 L
Now concentration of the concentrated KOH solution is:
Molarity = moles of KOH/vol of solution
= (45 g/56.105 g.mol-1)/0.069 L = 11.6 M
Thus,
Initial KOH concentration M1 = 11.6 M
Initial volume = V1
Final concentration M2 = 1.20 M
Final volume V2 = 250 ml
M1*V1= M2*V2
V1 = M2*V2/M1 = 1.20*250/11.6 = 25.9 ml = 26 ml
Answer:
548 g/mol
Explanation:
The freezing point depression of a solvent occurs when a nonvolatile solute is added to it. Because of the interactions between solute-solvent, it is more difficult to break the bonds, so the phase change will need more energy, and the freezing point will drop, which is called cryoscopy.
The drop in temperature can be calculated by:
ΔT = Kf*W*i
Where Kf is the cryoscopy constant of the solvent, W is the molality, and i is the van't Hoff factor, which indicates the fraction of the solute that dissolves.
The molality represents how much moles (n) of the solute is presented in each kg of the solvent (m2), thus
W = n/m2
The number of moles is the mass of the solute (m1) in g, divided by the molar mass (M1) of it:
W = m1/(M1*m2)
So, by the data:
0.2214 = 0.632/(M1*0.00521)
0.00115M1 = 0.632
M1 = 548 g/mol
