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Veseljchak [2.6K]
3 years ago
5

20.0 moles, 1840 g, of a nonvolatile solute, C 3H 8O 3 is added to a flask with an unknown amount of water and stirred. The solu

tion is allowed to reach 90.0°C . The vapor pressure of pure water at this temperature is 528.8 mm Hg. The vapor pressure of the solution is 423.0 mm Hg. How many kg of water was present?
Physics
1 answer:
Anastasy [175]3 years ago
7 0

Answer:

0.144 kg of water

Explanation:

From Raoult's law,

Mole fraction of solvent = vapor pressure of solution ÷ vapor pressure of solvent = 423 mmHg ÷ 528.8 mmHg = 0.8

Let the moles of solvent (water) be y

Moles of solute (C3H8O3) = 2 mole

Total moles of solution = moles of solvent + moles of solute = (y + 2) mol

Mole fraction of solvent = moles of solvent/total moles of solution

0.8 = y/(y + 2)

y = 0.8(y + 2)

y = 0.8y + 1.6

y - 0.8y = 1.6

0.2y = 1.6

y = 1.6/0.2 = 8

Moles of solvent (water) = 8 mol

Mass of water = moles of water × MW = 8 mol × 18 g/mol = 144 g = 144/1000 = 0.144 kg

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mihalych1998 [28]

(a) -83.6 Hz

Due to the Doppler effect, the frequency of the sound of the train horn appears shifted to the observer at rest, according to the formula:

f' = (\frac{v}{v\pm v_s})f

where

f' is the apparent frequency

v = 343 m/s is the speed of sound

v_s is the velocity of the source of the sound (positive if the source is moving away from the observer, negative if it is moving towards the observer)

f is the original frequency of the sound

Here we have

f = 350 Hz

When the train is approaching, we have

v_s = -40.4 m/s

So the frequency heard by the observer on the platform is

f' = (\frac{343 m/s}{343 m/s - 40.4 m/s})(350 Hz)=396.7 Hz

When the train has passed the platform, we have

v_s = +40.4 m/s

So the frequency heard by the observer on the platform is

f' = (\frac{343 m/s}{343 m/s + 40.4 m/s})(350 Hz)=313.1 Hz

Therefore the overall shift in frequency is

\Delta f = 313.1 Hz - 396.7 Hz = -83.6 Hz

And the negative sign means the frequency has decreased.

(b) 0.865 m

The wavelength and the frequency of a wave are related by the equation

v=\lambda f

where

v is the speed of the wave

\lambda is the wavelength

f is the frequency

When the train is approaching the platform, we have

v = 343 m/s (speed of sound)

f = f' = 396.7 Hz (apparent frequency)

Therefore the wavelength detected by a person on the platform is

\lambda' = \frac{v}{f'}=\frac{343 m/s}{396.7 Hz}=0.865m

5 0
3 years ago
The volume of a gas at 400.0ml when the pressure is 1.00atm. at the same temperature, what is the pressure at which the volume o
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Answer:

5.025 atm

Change the 2.01 to ml then cross multiply

400/1= 2010/x

210/400=5.025

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3 years ago
The fastest man alive can run the 100 meter dash in 9.58 seconds, calculate average speed in meters per second
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Answer:

100 ÷ 9.58 = 10.44 (approximate answer)

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Balanced equations account for the conservation of mass.
uranmaximum [27]

Answer:

fff

Explanation:

f

6 0
3 years ago
Read 2 more answers
How do I figure out this
ahrayia [7]
The Atomic Number is equal to the amount of Protons and Electrons. To find the amount of Neutrons in an atom, you have to look at the Mass Number. The Mass Number is the SUM (_+_=_) of Protons and Neutrons in an atom. In this case, you will have to make up equations. For example: Argon. Argon's Mass Number is 40. You need to find the amount of Protons in the atom (18). Mass Number (40) - Protons (18) = Amount of Neutrons. 40-18=22.
Argon has 22 Neutrons, because Protons(18)+Neutrons(22)=Mass Number(40).

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