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:
a) acidic; [H+] = 10^-2.5 = 3 x 10^-3
b) basic; [H+] = 10^-11.7 = 2 x 10^-12
c) slightly acidic (almost neutral); [H+] = 10^-6.8 = 1.6 x 10^-7
d) acidic; [H+] = 10^-3.31 = 4.9 x 10^-4
Explanation:
pH < 7 is acidic; pH > 7 is basic; pH = 7 is neutral
[H+] = 10^-pH
Answer:
7.224 × 10^28 atoms
Explanation:
The number of moles contained in a substance (n) can be calculated from this expression:
nA = n × 6.02 × 10^23 atoms
Where;
nA = number of atoms of substance
n = number of moles of substance
Avagadro's number or constant = 6.02 × 10^23 atoms
Using nA = n × 6.02 × 10^23 atoms
In this question, there are 1.2 x 10^5 moles of neon (N). The number of atoms (nA) is as follows:
nA of neon = 1.2 x 10^5 × 6.02 × 10^23
nA = 7.224 × 10^ (5 + 23)
nA = 7.224 × 10^28 atoms
The number of neon atoms in 1.2 x 10^5 is 7.224 × 10^28 atoms.
The Answer is C . The differences in the magnetic force from place to place .
