Answer:
A. The cost of producing a kilowatt of power with fuel cell will be less than $30 in 2015
Question:
The options are;
a. Temperature
b. Thermal Energy
c. Hotness
d. Fire Energy
Answer:
The correct option is;
b. Thermal energy
Explanation:
A burner on a stove produces thermal energy which is used to raise the temperature of the metal container (kettle, pot or pans) in which items are placed for heating.
Thermal energy is the internal energy of the system given off as heat which when transferred from one body to another causes the temperature of the receiving body to rise. Thermal energy in a burner is given off when the gaseous fuel reacts or burns in the presence of or with oxygen to produce carbon dioxide and water vapor in an exothermic reaction.
4C + 5H₂ + 13/2O₂ (-125 kJ) → C₄H₁₀ + O₂ → CO₂ + H₂O (-2877 kJ).
1) Calculate the number of moles of O2 (g) in 300 cm^3 of gas at 298 k and 1 atm
Ideal gas equation: pV = nRT => n = pV / RT
R = 0.0821 atm*liter/K*mol
V = 300 cm^3 = 0.300 liter
T = 298 K
p = 1 atm
=> n = 1 atm * 0.300 liter / [ (0.0821 atm*liter /K*mol) * 298K] = 0.01226 mol
2) The reaction of a metal with O2(g) to form an ionic compound (with O2- ions) is of the type
X (+) + O2 (g) ---> X2O or
2 X(2+) + O2(g) ----> X2O2 = 2XO or
4X(3+) + 3O2(g) ---> 2X2O3
In the first case, 1 mol of metal react with 1 mol of O2(g); in the second case, 2 moles of metal react with 1 mol of O2(g); in the third, 4 moles of X react with 3 moles of O2(g)
So, lets probe those 3 cases.
3) Case 1: 1 mol of metal X / 1 mol O2(g) = x moles / 0.01226 mol
=> x = 0.01226 moles of metal X
Now you can calculate the atomic mass of the hypotethical metal:
1.15 grams / 0.01226 mol = 93.8 g / mol
That does not correspond to any of the metal with valence 1+
So, now probe the case 2.
4) Case 2:
2moles X metal / 1 mol O2(g) = x / 0.01226 mol
=> x = 2 * 0.01226 = 0.02452 mol
And the atomic mass of the metal is: 1.15 g / 0.02452 mol = 46.9 g/mol
That is similar to the atomic mass of titanium which is 47.9 g / mol and whose valece is 2+.
4) Case 3
4 mol meta X / 3 mol O2 = x / 0.01226 => x = 0.01226 * 4 / 3 = 0.01635
atomic mass = 1.15 g / 0.01635 mol = 70.33 g/mol
That does not correspond to any metal.
Conclusion: the identity of the metallic element could be titanium.
<span>0 °C. 8 °C. 29 °C. 15 °C.</span>
