Greenhouse effect is the process of trapping sun radiation in the earth surface, so as to make the planet warm. It is a natural phenomenon in which sun rays that enters the earth surface are re-radiated into the earth surface causing the heat trap in the earth.
In similar manner, green house also trap radiation inside the glass house. The sun rays once reach inside the glass house, strike on plants and objects and reflected back. For entire radiation to escape from the green house, the heat flow between the two points must be proportional to the temperature difference and thermal conductivity. The glass of which the green house are made up, have low thermal conductivity. So, temperature must rise inside glass house so to maintain the heat flow rate of incoming and outgoing radiation.
The green house glass are insulated and they trap the infrared emitted by the objects inside the green house from escaping outside. Since the infrared have longer wave lengths, it is released slowly.
Also, the thermal energy inside the glass house are transferred by convection process. But the glass walls and roof act as insulator, keeping the radiant energy from escaping outside the green house.<span />
To find the empirical formula you would first need to find the moles of each element:
58.8g/ 12.0g = 4.9 mol C
9.9g/ 1.0g = 9.9 mol H
31.4g/ 16.0g = 1.96 O
Then you divide by the smallest number of moles of each:
4.9/1.96 = 2.5
9.9/1.96 = 6
1.96/1.96 = 1
Since there is 2.5, you find the least number that makes each moles a whole number which is 2.
So the empirical formula is C5H12O2.
<u>Given information:</u>
Concentration of NaF = 0.10 M
Ka of HF = 6.8*10⁻⁴
<u>To determine:</u>
pH of 0.1 M NaF
<u>Explanation:</u>
NaF (aq) ↔ Na+ (aq) + F-(aq)
[Na+] = [F-] = 0.10 M
F- will then react with water in the solution as follows:
F- + H2O ↔ HF + OH-
Kb = [OH-][HF]/[F-]
Kw/Ka = [OH-][HF]/[F-]
At equilibrium: [OH-]=[HF] = x and [F-] = 0.1 - x
10⁻¹⁴/6.8*10⁻⁴ = x²/0.1-x
x = [OH-] = 1.21*10⁻⁶ M
pOH = -log[OH-] = -log[1.21*10⁻⁶] = 5.92
pH = 14 - pOH = 14-5.92 = 8.08
Ans: (b)
pH of 0.10 M NaF is 8.08
