Answer:
T2 = 550K
Explanation:
From Charles law;
V1/T1 = V2/T2
Where;
V1 is initial volume
V2 is final volume
T1 is initial temperature
T2 is final temperature
We are given;
V1 = 20 mL
V2 = 55 mL
T1 = 200 K
Thus from V1/T1 = V2/T2, making T2 the subject;
T2 = (V2 × T1)/V1
T2 = (55 × 200)/20
T2 = 550K
Hydroxyl ions are OH⁻ while hydronium ions are H₃O⁺ which is essentially H⁺ ions. The formula for pH is: pH = -log[H⁺]. So, the greater the concentration of H⁺ is, the lower the pH which indicates acidity. On the other hand, the greater the concentration of OH⁻, the greater the pH which indicates basicity. This is also a consequence of the equation: pH + pOH = 14.
Answer: The correct option is 3.
Explanation: We are given a compound which is made up of iron and oxygen only. The ratio of the two are given as:
This means that, number of iron ions are 2
Number of oxide ions are 3
From the above information, the formula becomes : 
The valency of iron = 3
Valency of oxide = 2
This compound is named as iron (III) oxide.
Hence, the correct option is 3
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:
Fossil fuels
Explanation:
Fossil fuels — natural gas, coal, and petroleum, and — provide most (63 %) of the energy consumed in the United States
The breakdown in 2019 was
Natural gas 38 %
Coal 24 %
Petroleum 1 %
