Answer:
(A) endothermic
(A) Yes, absorbed
Explanation:
Let's consider the following thermochemical equation.
2 Fe₂O₃(s) ⇒ 4 FeO(s) + O₂(g) ΔH = 560 kJ
Since ΔH > 0, the reaction is endothermic.
We can establish the following relations:
- 560 kJ are absorbed when 2 moles of Fe₂O₃ react.
- The molar mass of Fe₂O₃ is 160 g/mol.
Suppose 66.6 g of Fe₂O₃ react. The heat absorbed is:

17 protons 17 electrons 18 neutrons
Answer: The missing coefficient is 2.
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

As in the products, there are 2 atoms of sodium, thus there will be 2 atoms of of sodium in the reactant as well. This will balance the number of hydrogen and oxygen atoms as well.
Thus the missing coefficient is 2.
Answer:
The temperature is 288, 88K
Explanation:
We use the formula PV= nRT:
T= PV/nR
T= 0,987 atm x12 L/0,50 mol x 0,082 l atm/K mol
<em>T=288,88K</em>