Answer:
At the burner temp. and pressure, 18.85 litres of air is needed to completely combust each gram of propane
Explanation:
The combustion stoichiometry is as follows:
C₃H₈ + 5O₂ = 4 H₂O + 3CO₂ The molecular weights (g/mol) are:
MW 44 5x32 4x18 3x44
So each gram of propane is 1/44 = 0.02272 mol propane
and will need 5 x 0.02272 = 0.1136 mol oxygen
At 0.21 mol fraction oxygen in air, 0.1136 / 0.21 = 0.54 mol air is needed to burn the propane.
At the low pressure in the burner we can use the Ideal Gas Law
PV=nRT, or V = nRT/P
P = 1.1 x 101325 Pa = 111457 Pa
T = 195°C + 273 = 468 K
R = 8.314
and we calculated n = number of moles air = 0.54 mol
So V m³ = 0.54 x 8.314 x 468 / 111457 = 0.0188 m³ = 18.85 litres air.
After some thinking I have come to the conclusion that the answer is C.
Answer:
ΔH = -976.5 kJ
Explanation:
For the reaction given, there are 2 moles of benzene (C6H6). The heat of this reaction is -6278 kJ, which means that the combustion of 2 moles of benzene will lose 6278 kJ of heat. It is an exothermic reaction.
The value of ΔH, the enthalpy, is a way of measurement of the heat, and it depends on the quantity of the matter (number of moles).
So, 24.3 g of benzene has :
n = mass/ molar mass
n = 24.3/78.11
n = 0.311 moles
2 moles ------------ -6278 kJ
0.311 moles ----------- x
By a simple direct three rule:
2x = -1953.08
x = -976.5 kJ
Answer:
1.22 mL
Explanation:
Let's consider the following balanced reaction.
2 AgNO₃ + BaCl₂ ⇄ Ba(NO₃)₂ + 2 AgCl
The molar mass of silver chloride is 143.32 g/mol. The moles corresponding to 0.525 g are:
0.525 g × (1 mol/143.32 g) = 3.66 × 10⁻³ mol
The molar ratio of AgCl to BaCl₂ is 2:1. The moles of BaCl₂ are 1/2 × 3.66 × 10⁻³ mol = 1.83 × 10⁻³ mol.
The volume of 1.50 M barium chloride containing 1.83 × 10⁻³ moles is:
1.83 × 10⁻³ mol × (1 L/1.50 mol) = 1.22 × 10⁻³ L = 1.22 mL