Answer:
- 0.0413°C ≅ - 0.041°C (nearest thousands).
Explanation:
- Adding solute to water causes the depression of the freezing point.
<em>ΔTf = Kf.m,</em>
Where,
ΔTf is the change in the freezing point.
Kf is the freezing point depression constant (Kf = 1.86 °C/m).
m is the molality of the solution.
<em>Molality is the no. of moles of solute per kg of the solution.</em>
- <em>no. of moles of solute (glucose) = mass/molar mass</em> = (8.44 g)/(180.156 g/mol) = <em>0.04685 mol.</em>
<em>∴ molality (m) = no. of moles of solute/kg of solvent</em> = (0.04685 mol)/(2.11 kg) = <em>0.0222 m.</em>
∴ ΔTf = Kf.m = (1.86 °C/m)(0.0222 m) = 0.0413°C.
<em>∴ The freezing point of the solution = the freezing point of water - ΔTf </em>= 0.0°C - 0.0413°C = <em>- 0.0413°C ≅ - 0.041°C (nearest thousands).</em>
Answer: C
Explanation:
Put electron pairs about each atom such that there are 8 electrons around each atom (octet rule), with the exception of H, which is only surrounded by 2 electrons. Sometimes it's necessary to form double and triple bonds. Only C, N, O, P and S (rarely Cl) will form multiple bonds. Draw the Lewis dot structure for CF4.
The amount of heat absorbed or released by the system can be determined by the equation:
U = mCpΔT
where:
m = mass of material
Cp = specific heat capacity of material; in this case, Cpwater = 4.186 J/(g-°C)
ΔT = change in temperature of material
U = 18(4.186)(20-(-10)) = 2260.44 Joules or B.
A positive term means energy was absorbed.
Im pretty sure th answer is D: temp differences on earth surface
Subtracting the mass of (flask+water) from the empty flask gives:
95.023 g - 85.135 g = 9.888 grams of water
Dividing this by the given volume of 10.00 mL water gives:
9.888 grams of water / 10.00 mL of water = 0.9888 g/mL of water
Therefore, based on this sample, the density of water is 0.9888 g/mL, which is close to the usually accepted approximation of 1 g/mL.
