67.8 grams of hydrogen gas are produced, how many grams of iron were used in this reaction
1 answer:
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Answer:
Q = 450 J
Explanation:
Given that,
Mass of a piece of glass, m = 45 g
The temperature changes from 10°C to 30°C.
The specific heat is 0.5 J/g°C
We need to find heat required to raise the temperature. The formula that is used to find it is given by :
So, the required heat is 450 J. Hence, the correct option is (c).
Answer : The value of for the reaction is, -390.3 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The main chemical reaction is:
The intermediate balanced chemical reaction are:
(1)
(2)
(3)
Now we are reversing reaction 1, multiplying reaction 3 by 2 and then adding all the equations, we get :
(1)
(2)
(3)
The expression for enthalpy change for the reaction will be,
Therefore, the value of for the reaction is, -390.3 kJ