Answer:
Explanation:
Mass of compound A = 25g
Mass of compound B = 40g
Mass of final mixture = 55g
What happens to the missing mass?
According to the law of conservation of mass, in chemical reaction, matter is transformed from one form to another but cannot be created nor destroyed.
We expect the final mass of the mixture and that of the reacting compounds to be the same but the opposite is the case.
There is a mass loss which typifies most chemical reaction.
The reason for this is that some of the masses must have been lost by the production of gaseous species which are unaccounted for.
The missing mass:
Total mass expected = mass of A + mass of B = 25 + 40 = 65g
Missing mass = expected mass - mass of final mixture = 65 - 55 = 10g
Answer:
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Explanation:
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
Answer:
B
Explanation:
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Periodic table is arranged according to atomic size and other properties.
