Endothermic or exothermic reaction?

[lanvins]

is the following an exothermic or endothermic reaction; S2O3 -2 (aq) + 2H+ (aq) --------> S(s) + SO2(g) + H2O(l)?

Note. We heated the sodium thiosulfate and water to 40oC then added HCl

and another thing, why did the sodium thiosulfate  have to be diluted before the hydrochloric acid was added??

[ganges]

is the following an exothermic or endothermic reaction; S2O3 -2 (aq) + 2H+ (aq) --------> S(s) + SO2(g) + H2O(l)?

Note. We heated the sodium thiosulfate and water to 40oC then added HCl

and another thing, why did the sodium thiosulfate  have to be diluted before the hydrochloric acid was added??

you can look at the chart they give u with the periodic table. if poitive/negative change in (delta) H

[dusty_girl1144]

is the following an exothermic or endothermic reaction; S2O3 -2 (aq) + 2H+ (aq) --------> S(s) + SO2(g) + H2O(l)?

Note. We heated the sodium thiosulfate and water to 40oC then added HCl

and another thing, why did the sodium thiosulfate  have to be diluted before the hydrochloric acid was added??

if there is a negative in front of the delta then the reaction is exothermic.
if there is a positive in front of the delta sign then the reaction is endothermic. but you MUST be give that delta info to know.
it says in my text book that tempreture tends to speed up the reaction. if this is so... then it must be exothermic???

sorry im not so sure about the thiosulphate being diluted. coz i only see that equation as a ionic equation....

[Collin Li]

it says in my text book that tempreture tends to speed up the reaction. if this is so... then it must be exothermic???

Nope. Temperature speeds up the reaction regardless of the nature of the change in enthalpy.

[dusty_girl1144]

it says in my text book that tempreture tends to speed up the reaction. if this is so... then it must be exothermic???

Nope. Temperature speeds up the reaction regardless of the nature of the change in enthalpy.

thanxs for clearing that up for me ^^

[lanvins]

I know that an increase in temperature causes a net backward reaction for exothermic reactions.

,so if you were to decrease the temperature would you describe it as a forwards exothermic reaction or a forwards endothermic reaction?

Thanks

[Mao]

if the reaction mixture was already at equilibrium, then decreasing the temperature will cause a net forward reaction [which you have told us is exothermic]

is that what you wanted to know?

[lanvins]

but is it a net forwards exothermic reaction or net a forwards endothermic reaction?

[Mao]

but is it a net forwards exothermic reaction or net a forwards endothermic reaction?

but you've already said the forward reaction is exothermic. so the result is net forward, and forward is exothermic.

if it wasn't, we cannot deduce a decrease in T will result in a net forward reaction. (in fact, we'll work it out to be a net backwards reaction)

[lanvins]

How do you know if it's an endothermic or exothermic reaction when the enthalpy charge isn't provided? like....

1. The reaction of SO2(g) with O2(g) in the presence of
vanadium (V) oxide.

2. S(s) + O2(g) ---> SO2(g)

[Mao]

How do you know if it's an endothermic or exothermic reaction when the enthalpy charge isn't provided? like....

1. The reaction of SO2(g) with O2(g) in the presence of
vanadium (V) oxide.

2. S(s) + O2(g) ---> SO2(g)

both of these are in the contact process to produce sulfuric acid. it should be general knowledge that all reactions in the contact process are exothermic.

for these two particular cases, the enthalpies are

1) -197 kJ/mol
2) -297 kJ/mol

(heinemann textbook, p341)

[lanvins]

thanks mao, i'm not quite up to there yet

[Collin Li]

both of these are in the contact process to produce sulfuric acid. it should be general knowledge that all reactions in the contact process are exothermic.

Only if you are studying sulfuric acid as the chemical of choice.

[Mao]

both of these are in the contact process to produce sulfuric acid. it should be general knowledge that all reactions in the contact process are exothermic.

Only if you are studying sulfuric acid as the chemical of choice.

there are other contact processes?
I thought the "contact process" referred to the production of sulfuric acid only...

[Collin Li]

I meant that you do not need to know about the contact process if you aren't studying sulfuric acid.

Hence, it wouldn't be "general knowledge" that the reactions are exothermic.