Correct Question:
A chemist measures the enthalpy change ΔH during the following reaction: Fe(s) + 2HCl(g)-->FeCl2(s) + H2 ΔH=-157.0 kJ. Use this information to complete the table below. Round each of your answers to the nearest kJ/mol
Answer:
-314 kJ
+628 kJ
+157 kJ
Explanation:
The enthalpy change of a reaction measures the amount of heat that is lost or gained by it. If ΔH >0 the heat is gained, and the reaction is called endothermic, if ΔH<0, the heat is lost, and the reaction is called exothermic.
If the reaction is inverted, the value of ΔH is inverted too (the opposite endothermic reaction is exothermic), and if the reaction is multiplied by a constant, ΔH will be multiplied by it too.
1) 2Fe(s) + 4HCl --> 2FeCl2(s) + 2H2(g)
This reaction is the product of the given reaction by 2, so
ΔH = 2*(-157) = -314 kJ
2) 4FeCl2(s) + 4H2(g) --> 4Fe(s) + 8HCl(g)
This reaction is the inverted reaction given multiplied by 4, so
ΔH = 4*(157) = +628 kJ
3) FeCl2(s) + H2(g) --> Fe(s) + 2HCl
This reaction is the inverted reaction given, so
ΔH = +157 kJ
Answer: Option (b) is the correct answer.
Explanation:
State of a substance changes when heat is provided to a substance.
This is because when we heat water then intermoleclar forces present within its molecules tend to break down. Due to this molecules start to move away from each other.
As a result, kinetic energy of molecules increases and they collide rapidly. Hence, solid state of water changes into liquid state and upon excessive heating liquid state of water changes into vapor state.
Thus, we conclude that temperature of water needs to change in order to change its state of matter.
B is the answer , i got you
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Answer: -
92.4 s
Explanation: -
The decomposition reaction of a → b has a rate constant k = 0.00132 s⁻¹
From the rate constant we see that the reaction is of zero order.
The rate equation for a zero order reaction is
A₀ - A = kt
where A₀ = initial concentration.
T = time passed since start of reaction,
A is the amount present after t time passed.
A₀ = 0.156 M
A = A₀ - 78.1% of A₀
= 0.156 - 
x 0.156
= 0.156 - 0.122
= 0.034 M
Plugging into the formula
A₀ - A = kt
0.156 - 0.034 = 0.00132 x t
t = 
= 92.4 s
t =
