Given:
Ma = 31.1 g, the mass of gold
Ta = 69.3 °C, the initial temperature of gold
Mw = 64.2 g, the mass of water
Tw = 27.8 °C, the initial temperature of water
Because the container is insulated, no heat is lost to the surroundings.
Let T °C be the final temperature.
From tables, obtain
Ca = 0.129 J/(g-°C), the specific heat of gold
Cw = 4.18 J/(g-°C), the specific heat of water
At equilibrium, heat lost by the gold - heat gained by the water.
Heat lost by the gold is
Qa = Ma*Ca*(T - Ta)
= (31.1 g)*(0.129 J/(g-°C)(*(69.3 - T °C)-
= 4.0119(69.3 - T) j
Heat gained by the water is
Qw = Mw*Cw*(T-Tw)
= (64.2 g)*(4.18 J/(g-°C))*(T - 27.8 °C)
= 268.356(T - 27.8)
Equate Qa and Qw.
268.356(T - 27.8) = 4.0119(69.3 - T)
272.3679T = 7738.32
T = 28.41 °C
Answer: 28.4 °C
Concentration "molarity" of H₂SO₄ in this solution:
5 × 10⁻³ mol / dm³.
<h3>Explanation</h3>
What's the concentration of H⁺ ions in this solution?
![[\text{H}^{+}] = 10^{-\text{pH}}](https://tex.z-dn.net/?f=%5B%5Ctext%7BH%7D%5E%7B%2B%7D%5D%20%3D%2010%5E%7B-%5Ctext%7BpH%7D%7D)
,
where ![[\text{H}^{+}]](https://tex.z-dn.net/?f=%5B%5Ctext%7BH%7D%5E%7B%2B%7D%5D)
is in the unit mol / dm³.
![[\text{H}^{+}] = 10^{-2} \;\text{mol}\cdot\text{dm}^{-3}](https://tex.z-dn.net/?f=%5B%5Ctext%7BH%7D%5E%7B%2B%7D%5D%20%3D%2010%5E%7B-2%7D%20%5C%3B%5Ctext%7Bmol%7D%5Ccdot%5Ctext%7Bdm%7D%5E%7B-3%7D)
.
What's the concentration "molarity" of H₂SO₄ in this solution?
Sulfuric acid H₂SO₄ is a strong acid. Note the subscript "2". Each mole of this acid dissolves in water to produce two moles of H⁺ ions. It takes only 
of H₂SO₄ to produce twice as much H⁺ ions.
As a result, the <em>molarity</em> of H₂SO₄ is 5 × 10⁻³ mol / dm³ or 0.005 M.
<u>Given</u>:
Wavelength (λ) of the laser pulse = 545 nm = 5.45 * 10⁻⁹ m
Total energy of pulse = 4.85 mJ
<u>To determine:</u>
The number of photons in the laser of a given energy
<u>Explanation:</u>
Energy per photon (E) = hc/λ
where h = planck's constant = 6.626 *10⁻³⁴ Js
C = speed of light = 3*10⁸ m/s
λ = wavelength
E = 6.626 *10⁻³⁴ Js* 3*10⁸ms-1 /5.45 * 10⁻⁹ m = 3.65 * 10⁻¹⁹ J
Now,
# photons = total energy/Energy per photon
= 4.85 * 10⁻³ J* 1 photon / 3.65 * 10⁻¹⁹ J = 1.32 * 10¹⁶ photons
Ans: the laser pulse contains 1.32 * 10¹⁶ photons
Answer:
Solar energy is essentially the light and heat emitted from the sun
