Answer:
a. Br2 (l) → Br2(g) ΔH°rxn = 30.91 kJ/mol
Explanation:
Bond enthalpy is the energy which is required to break 1 mol of of bonds in gaseous covalent molecules. Bond breaking process can be endothermic or exothermic depending on the molecules association. The process needs to be performed in chemical laboratory under standard conditions.
Molar mass:
Atomic mass O = 16.0 a.m.u
O₃ = 16.0 x 3 => 48.0 g/mol
Therefore:
1 mole O₃ --------------- 48.0 g
0.020 mole O₃ ---------- ??
0.020 x 48.0 / 1 =
0.96 / 1 => 0.96 g
hope this helps!
Answer:
c. 29 J
Explanation:
Step 1: Given data
- Specific heat capacity of Pb (c): 0.13 J/g.K (= 0.13 J/g.°C)
- Initial temperature: 22 °C
Step 2: Calculate the temperature change
ΔT = 37 °C - 22 °C = 15 °C
Step 3: Calculate the heat (Q) required to raise the temperature of the lead piece
We will use the following expression.
Q = c × m × ΔT
Q = 0.13 J/g.°C × 15 g × 15 °C = 29 J
The element that has a complete valence electron shell is argon (Ar) since it is a noble gas in the last group on the periodic table.
Answer:
2666.7 hours
Explanation:
The key to solve this problem is that we are given the propane gas consumed in one hour by giving us the information of the volume consumed at 1 atm, 298 K (25 +273). Using the gas law we can calculate the rate of consumption of propane per hour, and from here we can calculate its mass and converting it to gallons and finally diving the 400 gallos by this number.
PV = nRT ∴ n = PV/RT
n = 1 atm x 165 L/ (0.08206 Latm/kmol x 298 K ) = 6.75 mol propane
Mass propane :
6.75 mol x 44 g/mol = 296.88 g
convert this to Kg:
296.88 g/ 1000 g/Kg = 0.30 Kg
calculate the volume in liters this represents by dividing by the density:
0.30 Kg / 0.5077 Kg/L = 0.59 L
changing this to gallons
0.59 L x 1 gallon/3.785 L = 0.15 gallon
and finally calculate how many hours the 400 gallons propane tank will deliver
400 gallon/ 0.15 gallon/hr = 2666.7 hr
