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skad [1K]
4 years ago
12

Work done by a system is positive or negative?

Chemistry
1 answer:
saul85 [17]4 years ago
6 0
The internal energy has the symbol U. Q is positive if heat is added to the system, and negative if heat is removed;

....."W is positive if work is done by the system"........

and negative if work is done on the system.


So, work done by a system is positive.
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Two metals (Metal A and Metal B) are both exposed to a laser which emits photons that have a greater energy than the work functi
Tresset [83]

Answer:

shorter than

equal to

Explanation:

Let us go back to the Einstein photoelectric equation;

KE = E - Wo

Where

KE = kinetic energy of the photoelectron

E = energy of the incident photon

Wo = work function of the metal

But KE = 1/2mv^2

Thus the velocity of the emitted photoelectron  is determined by the kinetic energy of the emitted photoelectron.

Since the work function of metal A is smaller than that of metal B, the kinetic energy of photoelectrons emitted from metal A is greater than that of photoelectrons emitted from metal B . Therefore, the velocity of electrons from metal A is greater than those from metal B.

From de Broglie relation;

λ = h/mv

Where;

λ = de Broglie wavelength

h = Plank's constant

m = mass

v = velocity

Metal A producing electrons with greater velocity will lead to a shorter de Broglie wavelength compared to those from metal B.

The number of photoelectrons ejected is determined by the intensity of the photons and not the energy of the incident photons or the work function of the metals. Since the two metals are exposed to the the same laser, equal number of photoelectrons are produced for metals A and B.

8 0
3 years ago
What is the mass in grams of each of the following samples? 1.505 mol of Ti 0.337 mol of Na
Masja [62]

Answer:

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Explanation:

1.505 mol Ti x (47.87g/1 mol) = 72.04g Ti

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5 0
3 years ago
The maximum oxygen uptake is known as the __________.
andrezito [222]
The maximum oxygen uptake is known as the VO2 max.
4 0
3 years ago
Read 2 more answers
Suppose you are presented with a clear solution of sodium thiosulfate, Na2S2O3 . How could you determine whether the solution is
navik [9.2K]

Explanation:

A solution is said to saturated when it cannot dissolve any extra solute in it. The extra solute put remains undissolved.

A solution is said to unsaturated, when the concentration of solute is less as compared to solubility of the solution it is said to be unsaturated.

A solution is said to be super saturated when it contains more of the solute than the solvent  can dissolve under normal conditions is called super saturated.

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4 years ago
2 of 20 Which intermolecular force or bond is primarily responsible for the solubility of CH3OH in water? lonic bonding Hydrogen
Vlad [161]

Answer:

Hydrogen bonding

Explanation:

As a rule of thumb, "likes dissolve like", meaning polar solutes dissolve in polar solvents and nonpolar solutes in nonpolar solvents. In this case, water is polar (<em>dipolar moment</em> = 1.85 Debye) dissolves methanol which is also polar (<em>dipolar moment</em> = 1.69 Debye). Besides being dipoles, both molecules have atoms of Hydrogen with a covalent bond to more electronegative atoms of Oxygen. When this happens, stronger dipole-dipole interactions appear known as Hydrogen bonding. There is an electrostatic attraction between H (positive charge density) and O (negative charge density).

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3 years ago
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