Answer:
a) 1.866 × 10 ⁻¹⁹ J b) 3.685 × 10⁻¹⁹ J
Explanation:
the constants involved are
h ( Planck constant) = 6.626 × 10⁻³⁴ m² kg/s
Me of electron = 9.109 × 10 ⁻³¹ kg
speed of light = 3.0 × 10 ⁸ m/s
a) the Ek ( kinetic energy of the dislodged electron) = 0.5 mu²
Ek = 0.5 × 9.109 × 10⁻³¹ × ( 6.40 × 10⁵ )² = 1.866 × 10 ⁻¹⁹ J
b) Φ ( minimum energy needed to dislodge the electron ) can be calculated by this formula
hv = Φ + Ek
where Ek = 1.866 × 10 ⁻¹⁹ J
v ( threshold frequency ) = c / λ where c is the speed of light and λ is the wavelength of light = 358.1 nm = 3.581 × 10⁻⁷ m
v = ( 3.0 × 10 ⁸ m/s ) / (3.581 × 10⁻⁷ m ) = 8.378 × 10¹⁴ s⁻¹
hv = 6.626 × 10⁻³⁴ m² kg/s × 8.378 × 10¹⁴ s⁻¹ = 5.551 × 10⁻¹⁹ J
5.551 × 10⁻¹⁹ J = 1.866 × 10 ⁻¹⁹ J + Φ
Φ = 5.551 × 10⁻¹⁹ J - 1.866 × 10 ⁻¹⁹ J = 3.685 × 10⁻¹⁹ J
Answer:
24.03 J/mol.ºC
Explanation:
For a calorimeter, the heat lost must be equal to the heat gained from water plus the heat gained from calorimeter, which has the same initial temperature as the water.
-Qal = Qw + Qc (minus signal represents that the heat is lost)
-mal*Cal*ΔTal = mw*Cw*ΔTw + Cc*ΔTc
Where m is the mass, C is the specific heat, ΔT is the temperature variation, al is from aluminum. w from water and c from the calorimeter. Cw = 4.186 J/gºC
-25.5*Cal*(22.7 - 100) = 99.0*4.186*(22.7 - 18.6) + 14.2*(22.7 - 18.6)
1971.15Cal = 1699.10 + 58.22
1971.15Cal = 1757.32
Cal = 0.89 J/g.ºC
The molar mass of Al is 27 g/mol
Cal = 0.89 J/g.ºC * 27 g/mol
Cal = 24.03 J/mol.ºC
Answer:
b
Explanation:
because i think it is right
Answer:
<h2><em><u>A</u></em><em><u>.</u></em><em><u> </u></em><em><u>Cl2</u></em><em><u>(</u></em><em><u>g</u></em><em><u>)</u></em><em><u> </u></em><em><u>+</u></em><em><u> </u></em><em><u>2NaBr</u></em><em><u>(</u></em><em><u>aq</u></em><em><u>)</u></em><em><u> </u></em><em><u>--</u></em><em><u>></u></em><em><u> </u></em><em><u>2NaCl</u></em><em><u>(</u></em><em><u>aq</u></em><em><u>)</u></em><em><u> </u></em><em><u>+</u></em><em><u> </u></em><em><u>Br2</u></em><em><u>(</u></em><em><u>g</u></em><em><u>)</u></em></h2>
Explanation:
This is because,
Chlorine atoms (Cl2) displaces with Bromine atoms (Br) in Sodium bromide (2NaBr) solution to give a result as, Sodium Chloride (2NaCl) and left out atom Bromine (Br)
