The combustion of isooctane (C₈H₁₈) is written below:
2 C₈H₁₈ (l) + 25 O₂ (g) → 16 CO₂ (g) + 18 H₂O (l)
The formula for heat of combustion is:
ΔHc = (∑Stoichiometric coefficient×ΔHf of products) - (∑Stoichiometric coefficient×ΔHf of reactants), where ΔHf is heat of formation.
ΔHf of isooctane = -259.2 kJ/mol
ΔHf of O₂ = 0 kJ/mol
ΔHf of CO₂ = -393.5 kJ/mol
ΔHf of H₂O = <span>-285.8 kJ/mol
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ΔHc = [(16 mol×-393.5 kJ/mol )+(18 mol×-285.8 kJ/mol)] - [(2 mol×-259.2 kJ/mol) + (25 mol*0 kJ/mol)]
ΔHc = -10,922 kJ
Elements in the same group in the periodic table have similar chemical properties. Hydrogen and Lithium, who both belong to alkali metal group, have the same chemical properties.
Answer:
a solution color becoming less intense due to dilution- is not an evidence of a chemical reaction
bubbles (gas formation) - evidence of a chemical reaction
explosion or fire - evidence of a chemical reaction
changes in color- evidence of a chemical reaction
precipitation- evidence of a chemical reaction
changes in temperature - evidence of a chemical reaction
a solid liquifying - is not an evidence of a chemical reaction
solution colors mixing - is not an evidence of a chemical reaction
Explanation:
A chemical change is not easily reversible and yields new substances. It is often accompanied by a loss or gain of heat.
In the answer section, i have shown some evidences that lead us to conclude that a chemical reaction has taken place. The occurrence of a chemical change often goes with the formation of new substances as earlier stated and any of these signs may accompany the process.
For instance, when a metal is dropped in dilute acid solution, bubble of hydrogen gas indicates that a chemical reaction has taken place.
Answer:
4. [A] = 0.10M; [B] = 0.00M
Explanation:
Hello,
In this case, the following options are missing:
1. [A] = 0.00M; [B] = 0.10M
2. [A] = 0.0010M; [B] = 0.00010M
3. [A] = 0.10M; [B] = 0.10M
4. [A] = 0.10M; [B] = 0.00M
Therefore, since the equilibrium constant is small, one could make up that at the beginning there is no B since not too much A is consumed during the reaction, consequently, the answer is:
4. [A] = 0.10M; [B] = 0.00M
In fact, in this case would be 0.00001M which is the smallest one from the given options, considering:
Best regards.
C. The atomic mass could be used to calculate the number of isotopes formed my the element.