Answer: A. The variable c
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Explanation:
Q = heat transferred
m = mass
c = specific heat
= delta T = change in temperature
Answer:

Explanation:
Let's rewrite the given word equation in its chemical balanced equation representation:
1. Lead(II) nitride is represented by lead, Pb, in an oxidation state of 2+, while nitride is a typical nitrogen anion with a state 3-. As a result, the lowest common multiple between 2 and 3 is 6, meaning 2 lead cations are needed to balance 3 nitrogen anions:
.
2. Ammonium sulfate consists of an ammonium cation with a 1+ charge and sulfate anion with a 2- charge, two ammonium cations needed:
.
3. Lead(II) sulfate would have one lead cation and one sulfate anion, as they have the same magnitude of charges with opposite signs:
.
4. Ammonium nitride would require three amonium cations to balance the nitride anion:
.
Let's write the balanced equation:

Answer:
-1104 kJ/mol
Explanation:
The change in the enthalpy of a reaction is equal to the difference between: the sum of the enthalpy changes of the bonds broken and the sum of the enthalpy changes of the bonds formed.
The bonds broken correspond to the cleavage of bonds of the reactants, the bonds formed correspond to the bonds of the products:
- we only break oxygen O=O bond, since carbon is not bonded to anything;
- we form two C=O bonds in carbon dioxide.
Therefore, the enthalpy change is calculated by:
