Answer:
Explanation:
Some theoretical knowledge is required here. We should understand that whenever we plot the natural logarithm, ln, of a concentration vs. time and obtain a straight line, this indicates a first-order reaction. That said, since this is the case here, we have a first-order reaction with respect to .
The linear equation has the following terms:
It is a linear form of the integrated first-order law equation:
Therefore, the rate constant, k, is:
The natural logarithm of initial molarity is:
Using the equation, we may substitute for t = 600 s and obtain the natural logarithm of the concentration at that time:
Take the antilog of both sides to find the actual molarity:
Answer:
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Explanation:
The lowering of the freezing point of a solvent is a colligative property ruled by the formula:
Where:
- ΔTf is the lowering of the freezing point
- Kf is the molal freezing constant of the solvent: 1.86 °C/m
- m is the molality of the solution
- i is the van't Hoff factor: the number of particles (ions) per unit of ionic compound.
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<u>a) molality, m</u>
- m = number of moles of solute/ kg of solvent
- number of moles of CaI₂ = mass in grams/ molar mass
- number of moles of CaI₂ = 25.00g / 293.887 g/mol = 0.0850667mol
- m = 0.0850667mol/1.25 kg = 0.068053m
<u>b) i</u>
- Each unit of CaI₂, ideally, dissociates into 1 Ca⁺ ion and 2 I⁻ ions. Thus, i = 1 + 2 = 3
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<u>c) Freezing point lowering</u>
- ΔTf = 1.86 °C/m × 0.068053m × 3 = 0.3797ºC ≈ 0.380ºC
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6.02*10^23 is Avagadro's number representing the number of molecules per mole of substance.
Answer:
D Cobalt
Explanation:
The volume of the sphere is 40 -25 = 15 cm^3
Density = mass/volume = 133 gm / 15 cm^3 = 8.87 gm/cm^3
which corresponds to Cobalt from the chart