Answer:
ΔH°r = -1562 kJ
Explanation:
Let's consider the following combustion.
C₂H₆(g) + 7/2 O₂(g) ⇒ 2 CO₂(g) + 3 H₂O(l)
We can calculate the standard heat of reaction (ΔH°r) using the following expression:
ΔH°r = ∑np × ΔH°f(p) - ∑nr × ΔH°f(r)
where,
ni are the moles of reactants and products
ΔH°f(i) are the standard heats of formation of reactants and products
The standard heat of formation of simple substances in their most stable state is zero. That means that ΔH°f(O₂(g)) = 0
ΔH°r = ∑np × ΔH°f(p) - ∑nr × ΔH°f(r)
ΔH°r = [2 mol × ΔH°f(CO₂) + 3 mol × ΔH°f(H₂O)] - [1 mol × ΔH°f(C₂H₆) + 7/2 mol × ΔH°f(O₂)]
ΔH°r = [2 mol × (-394.0 kJ/mol) + 3 mol × (-286.0 kJ/mol)] - [1 mol × (-84.00 kJ/mol) + 7/2 mol × 0]
ΔH°r = -1562 kJ
Answer:pure water is neutral . Lake water is acidic. Baking soda and soapy water are basic.
Explanation: 7 is neutral. The higher on the ph scale like 1-6 is acidic. The lower on the scale 8-13 is base or alkaline.
If you follow the octet rule, you know that an element must have 8 outside (or valence) electrons to be energetically favorable.
In CCl4, the carbon molecule forms four bonds; one for each chlorine atom. Each bond contains 2 electrons, so it is satisfied.
In PCl3, Phosphorous forms only 3 bonds with chlorine, which means in order to have 8 valence electrons, it also has a lone pair of electrons, not bonded with chlorine.
Now, in CCl4, picture the shape of the molecule like a plus sign, with the carbon in the middle and the chlorine at the four ends. It is symmetrical, and therefore is nonpolar.
In PCl3, the lone pair electrons <em>push</em>, so to speak, the 3 chlorine atoms away, making a T-shaped molecule. Since the chlorine is more electronegative than carbon, the molecule is unbalenced, making it polar.
When we know the numerical value of the equilibrium constant, we can make certain judgments about the extent of the chemical reaction. K > 1. If K is larger than 1, the mixture contains mostly products. K < 1. If K is less than 1, the mixture contains mostly reactants
the correct answer is C
