Answer:
Kb = 0.428 m/°C
Explanation:
To solve this problem we need to use the <em>boiling-point elevation formula</em>:
- <em>Tsolution</em> - <em>Tpure solvent</em> = Kb * m
Where <em>Tsolution</em> and <em>Tpure solvent</em> are the boiling point of the CS₂ solution (47.52 °C) and of pure CS₂ (46.3 °C), respectively. Kb is the constant asked by the problem, and m is the molality of the solution.
So in order to use that equation and solve for Kb, first we <em>calculate the molality of the solution</em>.
molality = mol solute / kg solvent
- Density of CS₂ = 1.26 g/cm³
- Mass of 410.0 mL of CS₂ ⇒ 410 cm³ * 1.26 g/cm³ = 516.6 g = 0.5166 kg
molality = 0.270 mol / 0.5166 kg = 0.5226 m
Now we <u>solve for Kb</u>:
<em>Tsolution</em> - <em>Tpure solvent</em> = Kb * m
- 47.52 °C - 46.3 °C = Kb * 0.5226 m
<span>We can use
the heat equation,
Q = mcΔT </span>
<span>Where Q is
the amount of energy transferred (J), m is the mass of the substance
(kg), c is
the specific heat (J g</span>⁻¹ °C⁻<span>¹) and ΔT is
the temperature difference (°C).</span>
Let's assume that the finale temperature is T.
Q = 1200 J
<span>
m = 36 g
c = 4.186 J/g °C</span>
ΔT = (T -
22)
By applying
the formula,
1200 J = 36 g
x 4.186 J/g °C x (T - 22)
(T - 22) = 1200 J / (36 g x 4.186 J/g °C)
(T - 22) = 7.96 °C
T = (7.96 + 22) °C = 29.96 °C
T = 30 °C
Hence,
the final temperature is 30 °C.
<span>λν = c
c= speed of light= 3.0x10^8 m/s
</span>λ=wavelength
v= frequency
Plug and Chug.
Answer:
MnO- Manganese Oxide
Explanation:
Empirical formula: This is the formula that shows the ratio of elements
present in a
compound.
How to determine Empirical formula
1. First arrange the symbols of the elements present in the compound
alphabetically to determine the real empirical formula. Although, there
are exceptions to this rule, E.g H2So4
2. Divide the percentage composition by the mass number.
3. Then divide through by the smallest number.
4. The resulting answer is the ratio attached to the elements present in
a compound.
Mn O
% composition 72.1 27.9
Divide by mass number 54.94 16
1.31 1.74
Divide by the smallest number 1.31 1.31
1 1.3
The resulting ratio is 1:1
Hence the Empirical formula is MnO, Manganese oxide
