Answer:
27.60 g urea
Explanation:
The <em>freezing-point depression</em> is expressed by the formula:
In this case,
- ΔT = 5.6 - (-0.9) = 6.5 °C
m is the molality of the urea solution in X (mol urea/kg of X)
First we<u> calculate the molality</u>:
- 6.5 °C = 7.78 °C kg·mol⁻¹ * m
Now we<u> calculate the moles of ure</u>a that were dissolved:
550 g X ⇒ 550 / 1000 = 0.550 kg X
- 0.84 m = mol Urea / 0.550 kg X
Finally we <u>calculate the mass of urea</u>, using its molecular weight:
- 0.46 mol * 60.06 g/mol = 27.60 g urea
Two solutions are made by mixing sugar and enough water to make a 1 liter solution. 10% sugar has more solvent.
In chemistry, a solution is a homogeneous mixture of two or more compounds in their relative proportions that can be continually altered up to what is referred to as the limit of solubility. Although the word "solution" is frequently used to refer to the liquid state of matter, solutions of gases and solids are also possible. A solute is dissolved by a solvent (s), which is a substance (from the Latin solv, "loosen, untie, solve,") to produce a solution. The most common form of a solvent is a liquid, although other forms include solids, gases, and supercritical fluids. Depending on the temperature, a different amount of solute can dissolve in a given volume of solvent. Solvents are extensively utilized in paints, paint removers, inks, and dry cleaning.
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<span>A. produces as much energy as cell respiration.</span>
Answer:
\large \boxed{\textbf{609 kJ}}
Explanation:
The formula for the heat absorbed is
q = mCΔT
Data:
m = 2.07 kg
T₁ = 23 °C
T₂ = 191 °C
C = 1.75 J·°C⁻¹g⁻¹
Calculations:
1. Convert kilograms to grams
2.07 kg = 2070 g
2. Calculate ΔT
ΔT = T₂ - T₁ = 191 - 23 = 168 °C
3. Calculate q
Absorbance is related to the concentration of a substance using the Beer-Lambert's Law. According to this law, absorbance is linearly related to concentration. However, this is only true up to a certain concentration depending on the substance. For this case, we assume that the said law is applicable.
A = kC
Using the first conditions, ewe solve for k.
0.26 = k (0.10)
k = 2.6
A = kC
A = 2.6 (0.20) = 0.52
Therefore, the absorbance at a concentration of 0.20 M and wavelength of 500nm is 0.52.
