Answer: option 3) 155 g
Explanation:
1) Releasing energy means that it changed from gas to liquid (or liquid to solid, but it is told that the NaCl changed into liquid).
That is because molecules in gas state are more energetic than in liquid state (molecules in gas state have more kinetic energy than molecules in liquid stated).
2) So, that means that the corresponding process is condenstation, and you have to use the latent heat of vaporization which is told to be 171 kJ/mol.
3) Calculations:
i) number of moles, n:
452 kJ = n × 171 kJ/mol ⇒ n = 452 kJ / 171 kJ/mol = 2.643 moles
ii) mass:
mass = n × molar mass = 2.643 moles × 58.443 g/mol = 154.46 g ≈ 155 g
We know this because of the discovery of fossils and bones. We can find out roughly when they existed because of carbon dating.
A, milligrams because rice is very small therefore you'd need to use a very small unit of measurement.
First c<span>alculate the mole fraction of each substance:
acetone: 2,88 mol </span>÷ (2,88 mol + 1,45 mol) = 0,665.
cyclohexane: 1,45 ÷ (2,88 mol + 1,45 mol) = 0,335.
Raoult's Law:
P(total) = P(acetone) · χ(acetone) + P(cyclohexane) · χ(cyclohexane).
P(total) = 229,5 torr · 0,665 + 97,6 torr · 0,335.
P(total) = 185,3 torr.
χ for acetone: 229,5 torr · 0,665 ÷ 185,3 torr = 0,823.
χ for cyclohexane: 97,6 torr · 0,335 ÷ 185,3 torr = 0,177.
