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Jobisdone [24]
3 years ago
12

A student collected a 40.0 mL sample of H_{2} 2 ​ gas at a temperature of 20.0°C and pressure of 720.0 mmHg. The next day the te

mperature was still 20.0°C but the sample's volume has decreased to 38.4 mL. What is the new pressure, in mm Hg?
Chemistry
1 answer:
Karo-lina-s [1.5K]3 years ago
6 0

Answer: 750 mmHg

Explanation:

To calculate the new pressure, we use the equation given by Boyle's law. This law states that pressure is inversely proportional to the volume of the gas at constant temperature.

The equation given by this law is:

P_1V_1=P_2V_2

where,

P_1 = initial pressure of gas= 720.0 mmHg

V_1 =  initial volume of gas = 40.0 ml

P_2 = final pressure of gas= ?

V_2 = final volume of gas = 38.4 ml

Putting values in above equation, we get:

720.0\times 40.0=P_2\times 38.4

P_2=750mmHg

Thus the new pressure will be 750 mmHg

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A light source of wavelength, l, illuminates a metal and ejects photoelectrons with a maximum kinetic energy of 1 eV. A second l
madreJ [45]

Explanation:

From first source, kinetic energy (K.E_{1}) ejected is 1 eV and wavelength of light is \lambda.

From second source, kinetic energy (K.E_{2}) ejected is 4 eV and wavelength of light is \frac{\lambda}{2}.

Relation between work function, wavelength, and kinetic energy is as follows.

                   K.E = \frac{hc}{\lambda} - \phi

where,        h = Plank's constant = 6.63 \times 10^{-34} J.s

                   c = speed of light = 3 \times 10^{8} m/s

Also, it is known that 1 eV = 1.6 \times 10^{-19} J

Therefore, substituting the values in the above formula as follows.

  • From first source,

                      K.E_{1} = \frac{hc}{\lambda} - \phi  

            1 eV = 1.6 \times 10^{-19} J = \frac{6.63 \times 10^{-34} \times 3 \times 10^{8}}{\lambda} - \phi    

    1.6 \times 10^{-19} J = \frac{1.98 \times 10^{-25} J.m}{\lambda} - \phi        ........... (1)

  • From second source,

                  K.E_{2} = \frac{hc}{\lambda} - \phi  

          4 \times 1.6 \times 10^{-19} J = \frac{6.63 \times 10^{-34} \times 3 \times 10^{8}}{\frac{\lambda}{2}} - \phi        

                 6.4 \times 10^{-19} J = \frac{2 \times 1.98 \times 10^{-25} J.m}{\lambda} - \phi        ........... (2)        

Now, divide equation (2) by 2. Therefore, it will become

       {6.4 \times 10^{-19}J}{2} = \frac{2 \times 1.98 \times 10^{-25} J.m}{2\lambda} - \frac{\phi}{2}

                3.2 \times 10^{-19}J = \frac{1.98 \times 10^{-25} J.m}{\lambda} - \frac{\phi}{2}   ......... (3)

Now, subtract equation (3) from equation (1), we get the following.

                 1.6 \times 10^{-19} = \frac{\phi}{2}

                    \phi = 3.2 \times 10^{-19}

                          = 2 eV

Thus, we can conclude that work function of the metal is 2 eV.

3 0
3 years ago
PLEASE HELP WILL MARK BRAINLIEST
Zielflug [23.3K]

Answer:

1. There are 7 categories:

Radio waves, microwaves, infrared heat waves, visible light spectrum, ultraviolet waves, x-rays, gamma rays

2. They are all electromagnetic radiation.

3. The amount of energy the photons within them have.

4. The longer the wavelength, the less energy. The shorter the wavelength, the more energy. They are inversely proportional.

5. As the wavelength increases, the smaller the frequency. The shorter the wavelength, the larger the frequency. They are inversely proportional. Also, wavelength is measured in meters and frequency is measured in hertz (cycles per second). They are two of the 3 ways EM radiation is expressed.

6/7 Reds have the least. Violets have the most.

8. Violet has the shortest. Red has the longest.

9. Ultra Violet B-Rays (UV-B) are the harmful rays that cause sunburn.

10. Microwaves are generally used for radar technology.

11/12 You are exposed to all of the categories of the electromagnetic spectrum everyday of every year. You just can't see/feel them all.

hope this helps! stay happy and healthy, friend! :))

Explanation:

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Compare the seasons on Titan to the seasons on Earth.
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Since Titan orbits roughly along Saturn's equatorial plane, and Titan's tilt relative to the sun is about the same as Saturn's, Titan's seasons are on the same schedule as Saturn's—seasons that last more than seven Earth years, and a year that lasts 29 Earth years.
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A chemist prepares a sample of helium gas at a certain pressure, temperature and volume and then removes all but a fourth of the
cupoosta [38]

Answer:

The temperature must be changed to 4 times of the initial temperature so as to keep the pressure and the volume the same.

Explanation:

Pressure in the container is P and volume is V.

Temperature of the helium gas molecules =T_1

Molecules helium gas = x

Moles of helium has = n_1= \frac{x}{N_A}

PV = nRT (Ideal gas equation)

PV=n_1RT_1...[1]  

After removal of helium gas only a fourth of the gas molecules remains and pressure in the container and volume should remain same.

Molecules of helium left after removal = \frac{x}{4}

Moles of helium has left after removal = n_2= \frac{x}{4\times N_A}

PV=n_2RT_2...[2]

n_1RT_1=n_2RT_2

\frac{x}{N_A}\times T_1=\frac{x}{4\times N_A}\times T_2

T_1=\frac{T_2}{4}

T_2=4T_1

The temperature must be changed to 4 times of the initial temperature so as to keep the pressure and the volume the same.

6 0
3 years ago
The elements found in Group 2A, from top to bottom, include beryllium, magnesium, calcium, strontium, and barium. Which of these
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Electronegativity is the property of the element to attract electrons to its nucleus. The trend of electronegativity in the periodic table is decreasing from right to left and decreasing from top to bottom. hence from the given elements, the element with the highest electronegativity should be A.beryllium 
5 0
3 years ago
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