Answer:
ΔHr = -86.73 kJ/mol
Explanation:
Using Hess's law, you can calculate ΔH of any reaction using ΔH°f of products and reactants involed in the reaction.
<em>Hess law: ∑nΔH°f products - ∑nΔH°f reactants = ΔHr</em>
<em>-Where n are moles of reaction-</em>
For the reaction:
Fe³⁺(aq) + 3 OH⁻(aq) → Fe(OH)₃(s)
Hess law is:
ΔHr = ΔH°f Fe(OH)₃ - ΔH°f Fe³⁺ - 3×ΔH°f OH⁻
Where:
ΔH°f Fe(OH)₃: −824.25 kJ/mol
ΔH°f Fe³⁺: −47.7 kJ/mol
ΔH°f OH⁻: −229.94 kJ/mol
Replacing:
ΔHr = −824.25 kJ/mol - (−47.7 kJ/mol) - (3×-229.94 kJ/mol)
<em>ΔHr = -86.73 kJ/mol</em>
Answer:
C is the answer they are looking for but clearly the truth is D
Explanation:
Answer:
68.6 °C
Explanation:
From conservation of energy, the heat lost by acetone, Q = heat gained by aluminum, Q'
Q = Q'
Q = mL where Q = latent heat of vaporization of acetone, m = mass of acetone = 3.33 g and L = specific latent heat of vaporization of acetone = 518 J/g
Q' = m'c(θ₂ - θ₁) where m' = mass of aluminum = 44.0 g, c = specific heat capacity of aluminum = 0.9 J/g°C, θ₁ = initial temperature of aluminum = 25°C and θ₂ = final temperature of aluminum = unknown
So, mL = m'c(θ₂ - θ₁)
θ₂ - θ₁ = mL/m'c
θ₂ = mL/m'c + θ₁
substituting the values of the variables into the equation, we have
θ₂ = 3.33 g × 518 J/g/(44.0 g × 0.9 J/g°C) + 25 °C
θ₂ = 1724.94 J/(39.6 J/°C) + 25 °C
θ₂ = 43.56 °C + 25 °C
θ₂ = 68.56 °C
θ₂ ≅ 68.6 °C
So, the final temperature (in °C) of the metal block is 68.6 °C.
Answer:
0.2 moles, assuming weight of dried salt
Explanation:
In order to determine the number of moles, we need to be aware of the mass of the substance in question.
Assuming the mass of the dehydrated 
is 50g.
No. of moles = mass of substance/ molar mass of the substance.
= 
= 0.2 moles moles.
Answer:
d.) Microwave photons cause the molecules to increase their rotational energy states, whereas infrared photons cause electrons in the molecules to increase their electronic energy states.
Explanation:
Microwave: transitions in the molecular rotational levels
Infrared: transitions in molecular vibrational levels
UV/Visible: transitions in electronic energy levels.
