Answer:
option B= Al, Ga and In
Explanation:
Properties of Boron group:
- These elements are belongs to boron group which is thirteen group of periodic table. There are six elements are in this group boron, aluminium, gallium, indium, thallium and nihonium.
- They are also called p-block elements because their valance electrons are present in p subshell.
- All these elements have three valance electrons.
- Boron is metalloid while other elements are metals.
- Their oxidation state is +3 because of tendency to lose three valance electrons and create positive charge.
- Their atomic sizes increases down the group with increase of atomic number.
- Their ionization energies decreases down the group because of increase of atomic radius and ease of removing of electrons.
Answer : The standard enthalpy of formation of ethylene is, 51.8 kJ/mole
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The formation reaction of 
will be,
The intermediate balanced chemical reaction will be,
(1) 
(2) 
(3) 
Now we will reverse the reaction 1, multiply reaction 2 and 3 by 2 then adding all the equations, we get :
(1) 
(2) 
(3) 
The expression for enthalpy of formation of will be,
Therefore, the standard enthalpy of formation of ethylene is, 51.8 kJ/mole
Answer:
The temperature should be higher than 437.9 Kelvin (or 164.75 °C) to be spontaneous
Explanation:
<u>Step 1:</u> Data given
ΔH∘=20.1 kJ/mol
ΔS is 45.9 J/K
<u>Step 2:</u> When is the reaction spontaneous
Consider temperature and pressure = constant.
The conditions for spontaneous reactions are:
ΔH <0
ΔS > 0
ΔG <0 The reaction is spontaneous at all temperatures
ΔH <0
ΔS <0
ΔG <0 The reaction is spontaneous at low temperatures ( ΔH - T*ΔS <0)
ΔH >0
ΔS >0
ΔG <0 The reaction is spontaneous at high temperatures ( ΔH - T*ΔS <0)
<u>Step 3:</u> Calculate the temperature
ΔG <0 = ΔH - T*ΔS
T*ΔS > ΔH
T > ΔH/ΔS
In this situation:
T > (20100 J)/(45.9 J/K)
T > 437.9 K
T > 164.75 °C
The temperature should be higher than 437.9 Kelvin (or 164.75 °C) to be spontaneous
Answer:
the balanced equation to the combustion of gasoline is C8H18 + 12.5 O2 → 8 CO2 + 9 H2O (1)
