I believe that number 27 is A
The reaction creates dihydrogen, hence if it's uncontrolled it could lead to potentially dangerous amounts of gas being released at once.
Answer:
Explanation:
The oxidation number is an integer that represents the number of electrons that an atom receives or makes available to others when it forms a given compound.
The oxidation number is positive if the atom loses electrons, or shares them with an atom that has a tendency to accept them. And it will be negative when the atom gains electrons, or shares them with an atom that has a tendency to give them up.
Chemical compounds are electrically neutral. That is, the charge that all the atoms of a compound contribute must be globally null. That is, when having positive or negative charges in a compound, their sum must be zero.
There are some rules for determining oxidation numbers in compounds. Among them it is possible to mention:
- Hydrogen (H) has an oxidation number +1 with nonmetals and - 1 with metals.
- Oxygen (O) presents the oxidation number -2
- Fluorine F has a unique oxidation state -1
Then:
- NOF: N+(-2)+(-1)=0 → N=3 → oxidation number of nitrogen (N) is +3, oxidation number of oxygen (O) is -2 and oxidation number of fluorine (F) is -1.
- ClF₅: Cl + 5*(-1)=0 → Cl= 5 → oxidation number of chlorine (Cl) is +5 and oxidation number of fluorine (F) is -1.
- H₂SO₃: 2*(+1)+S+3*(-2)=0 → S=4 → oxidation number of hydrogen (H) is +1, oxidation number of oxygen (O) is -2 and oxidation number of sulfur (S) is +4.
Ca(OH)2(aq) + 2HCl(aq)------> CaCl2(aq) + 2H2O(l) ΔH-?
CaO(s) + 2HCl(aq)-----> CaCl2(aq) + H2O(l), Δ<span>H = -186 kJ
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CaO(s) + H2O(l) -----> Ca(OH)2(s), Δ<span>H = -65.1 kJ
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1) Ca(OH)2 should be reactant, so
CaO(s) + H2O(l) -----> Ca(OH)2(s)
we are going to take as
Ca(OH)2(s)---->CaO(s) + H2O(l), and ΔH = 65.1 kJ
2) Add 2 following equations
Ca(OH)2(s)---->CaO(s) + H2O(l), and ΔH = 65.1 kJ
<span><u>CaO(s) + 2HCl(aq)-----> CaCl2(aq) + H2O(l), and ΔH = -186 kJ</u>
</span>Ca(OH)2(s)+CaO(s) + 2HCl(aq)--->CaO(s) + H2O(l)+CaCl2(aq) + H2O(l)
Ca(OH)2(s)+ 2HCl(aq)---> H2O(l)+CaCl2(aq) + H2O(l)
By addig these 2 equation, we got the equation that we are needed,
so to find enthalpy of the reaction, we need to add enthalpies of reactions we added.
ΔH=65.1 - 186 ≈ -121 kJ
It can take 49 days, I could be wrong. What do you mean in this question?
