Change of state from a solid directly to a gas

study the timeline♡based on fossil evidence about how long ago did the first single-celled life form appear on earth NEED ANSWER

Kipish [7]

4.1 billion years ago

6 0

3 years ago

A chemical measured the amount of barium sulfide produced during an experiment she finds that 823g of barium sulfide is produced

fenix001 [56]

Answer:

4.86moles of barium sulfide are produced

Explanation:

To solve this question we need to convert the mass of barium sulfide (BaS) to moles using the molar mass of BaS:

Molar mass BaS:

1 Ba atom = 137.3g/mol

1 S atom = 32.1g/mol

Molar mass BaS = 137.3 + 32.1 = 169.4g/mol

Moles in 823g of BaS:

823g * (1mol / 169.4g) =

<h3>4.86moles of barium sulfide are produced</h3>

7 0

3 years ago

The work function of an element is the energy required to remove an electron from the surface of the solid element. The work fun

Anton [14]

Explanation:

The given data is as follows.

Energy needed for 1 mole = 279.7 kJ = $279.7 \times \frac{1000 J}{1 kJ}$

= 279700 J

Therefore, energy required for 1 atom will be calculated as follows.

$\frac{279700}{6.022 \times 10^{22}}$

= $4.645 \times 10^{-19} J$

As relation between energy and wavelength is as follows.

E = $\frac{hc}{\lambda}$

where, h = planck constant = $6.62 \times 10^{-34} Js$

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

$\lambda$ = wavelength

Therefore, putting given values into the above formula as follows.

E = $\frac{hc}{\lambda}$

$4.645 \times 10^{-19} J$ = $\frac{6.62 \times 10^{-34} Js \times 3 \times 10^{8} m/s}{\lambda}$

$\lambda$ = $4.28 \times 10^{-7} m$

or, = $428 \times 10{-9}$ m

= 428 nm

Thus, we can conclude that the maximum wavelength of light that can remove an electron from an atom on the surface of lithium metal is 428 nm.

4 0

3 years ago

A flask at room temperature contains exactly equal amounts (in moles) of nitrogen and xenon.

zalisa [80]

Answer:

a) Same

b) Nitrogen

c) Same

d) Nitrogen

Explanation:

a)

The formula for partial pressure of a gas is equal to

$p_B = n_B \frac{RT}{V}$

Here nB is the number of moles .

The number of moles for both the gases are same and hence the partial pressure for the two gases will also be same.

b) The greater average velocity is calculated by using following formula

$v_{RMS} = \sqrt{3RTM}$

Here M is the molar mass.

Molar mass of nitrogen is greater than the molar mass of xenon and hence nitrogen will have higher greater average velocity

c) As we know, the average kinetic energy of gas particles is dependent on the absolute temperature of gas and if all the gases are at same temperature, their kinetic energy will also be same. Since nitrogen and xenon are at same temperature, their kinetic energy will be same

d) Effusivity is depended directly on the thermal conductivity, density and and the specific heat capacity.

All these three parameters are higher in case of nitrogen. Thus, it will effuse first

4 0

3 years ago

Lotions applied during winter season moisturize the skin very quickly. What could be the reason for this?

irina1246 [14]

I think the correct answer from the choices listed above is option C. Lotions applied during winter season moisturize the skin very quickly. This is because the oils in the lotion enter the skin cells by means of facilitated diffusion. Hope this answers the question.

4 0

3 years ago

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