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3 years ago

What is the threshold frequency ν0 of cesium?

1 answer:

Montano1993 [528]3 years ago

4 0

I think this is what you're after:

Cs(g) → Cs^+ + e⁻ ΔHIP = 375.7 kJ mol^-1 [1]

Convert to J and divide by the Avogadro Const to give E in J per photon

E = 375700/6.022×10^23 = 6.239×10^-19 J

Plank relationship E = h×ν E in J ν = frequency (Hz s-1)

Planck constant h = 6.626×10^-34 J s

6.239×10^-19 = (6.626×10^-34)ν

ν = 9.42×10^14 s^-1 (Hz)

IP are usually given in ev Cs 3.894 eV

E = 3.894×1.60×10^-19 = 6.230×10^-19 J per photon

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What is the mass of 0.714 moles of Mercury (I) Chloride (Hg2Cl2)?

ArbitrLikvidat [17]

Data:

m (Sample Mass) = ?
n (Number of moles) = 0.714 mol
MM (Molar Mass) of Mercury (I) Chloride ( $Hg_{2} Cl_{2}$ )
Hg = 2*200.59 = 401.18 amu
Cl = 2*35.453 = 70.906 amu
----------------------------------------
Molar Mass $Hg_{2} Cl_{2}$ = 401.18 + 70.906 = 472.086 ≈ 472.09 amu or 472.09 g/mol

Formula:

$n = \frac{m}{MM}$

Solving:

$n = \frac{m}{MM}$
$0.714 = \frac{m}{472.09}$
$m = 337.07226\:\to\:\boxed{\boxed{m\approx 337 g}} \end{array}}\qquad\quad\checkmark$

Answer:
By approximation would be letter D) 337.2 g

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3 years ago

Harriet has an itch in her throat, and she begins to cough. she reaches for a cup of water to drink. which action is carried out

Nikitich [7]

when she reaches for the cup that is somatic nervous system. when she begins to cough

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3 years ago

An electrochemical cell has the following standard cell notation: Al(s) | Al3+(aq) || Mg2+(aq) | Mg(s)

Soloha48 [4]

Answer:

a. Al(s) ⇄ Al⁺³(aq) + 3e⁻ (oxidation)

Mg²⁺(aq) + 2e⁻ ⇄ Mg(s) (reduction)

b. ΔE° = + 0.715 V

c. It's an electrolytic cell, because it's a nonspontaneous reaction.

d. 2Al(s) + 3Mg²⁺(aq) ⇄ 2Al⁺³(aq) + 3Mg(s)

Explanation:

a. By the notation given, first is represented the oxidation reaction and then the reduction reaction, so they are:

Al(s) ⇄ Al⁺³(aq) + 3e⁻ (oxidation)

Mg²⁺(aq) + 2e⁻ ⇄ Mg(s) (reduction)

b. The standard potential of the cell (ΔE°) is the reduction potential of the oxidation less the reduction potential of the reduction. The reduction potentials are:

Al(s) = -1.66 V

Mg(s) = -2.375 V

ΔE° = -1.66 - (-2.375)

ΔE° = + 0.715 V

c. It's an electrolytic cell.

A galvanic cell is spontaneous, so the cathode (reduction) has a higher E° than the cathode (oxidation). In this case, the oxidation reaction has a higher E°, so the reaction is nonspontaneous and it's necessary an external force to it happen, so it's an electrolytic cell.

d. 2Al(s) + 3Mg²⁺(aq) ⇄ 2Al⁺³(aq) + 3Mg(s)

The number of electrons must be the same, so the oxidation reaction is multiplied by 2, and the reduction reaction by 3.

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3 years ago

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klio [65]

C. decomposition reaction

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3 years ago

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Answer:

The white powder is not sugar, so Christy's hypothesis is incorrect . Christy's next step should be to identify substances that have the measured molecular mass.

Explanation:

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4 years ago