we knnow
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(c) Some endothermic reactions occur spontaneously at room temperature. Some exothermic reactions do not occur if the reactants are heated together to a very high temperature.
In order to explain the following observations, another factor, the entropy change, ΔS, must be considered. The equation which relates ΔS to ΔH is given below.
ΔG = ΔH – TΔS
(i) Explain why the following reaction occurs at room temperature even though thereaction is endothermic.
NaHCO3(aq) + HCl(aq) → NaCl(aq) + H2O(l) + CO2(g)
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Kian Stevens
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As it says in the question: ΔS must be considered.

For a reaction to be spontaneous at a temperature T, then ΔG must be negative. Hence, for the reaction in the question, ΔG must be negative at room temperature.
This must mean the reaction has a positive ΔS value, as this would make TΔS greater than ΔH, meaning that ΔG would be negative.
This can be verified if you look at what's being formed: you have a gas being formed, meaning that the system increases in disorder, and so the entropy will increase (giving a positive ΔS value).
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Mr.noname
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In addition to what has already been said also look at the no. of moles of substance I.e. 2 moles of reactants forms 3 moles of product, so the entropy increases as the disorder increases.
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Kian Stevens
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(Original post by Mr.noname)
In addition to what has already been said also look at the no. of moles of substance I.e. 2 moles of reactants forms 3 moles of product, so the entropy increases as the disorder increases.
Thanks for adding extra valuable information
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