• Study Resource
• Explore

Survey

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

History of the battery wikipedia, lookup

State of matter wikipedia, lookup

Gibbs free energy wikipedia, lookup

Enthalpy wikipedia, lookup

Transcript
```200
(1) Ice melts spontaneously above 0ÂºC with the absorption of heat from the surroundings.
above
ÎH = +6.0 kJ molâ1
Ice â¯â¯
â¯â H 2 0 (l) ,
0ÂºC
(2) NaCl dissolves spontaneously in water with the absorption of heat.
NaCl (s) + aq â¯â¯
â Na + (aq) + Cl â (aq) , ÎH = +3.9 kJ molâ1
*10.
Ans.
*11.
Ans.
Is it possible for a reaction to be nonspontaneous yet exothermic? Explain with example.
Normally exothermic process are spontaneous but there are some processes which are nonspontaneous inspite of being exothermic. For example : H2O(l) at 1 atm. and 0ÂºC forms ice.
Here both the phases are in equilibrium. This process is non-spontaneous.
1atm,0ÂºC
H 2 O(l) H 2 O(s) ;
H < 0.
Predict the sign of ÎS in the following processes. Give reasons for your answer.
(a) N 2 O 4 (g) â¯â¯
â 2NO 2 (g)
sign of ÎS is +ve as disorder in the product are larger than in the reactants.
(b) Fe 2O 3 (s) + 3H 2 (g) â¯â¯
â 2Fe(s) + 3H 2 O(g)
Ans.
reaction is in equilibrium, ÎS = 0.
(c) N 2 (g) + 3H 2 (g) â¯â¯
â 2NH 3 (g)
Ans.
sign of ÎS is âve, as disorder in the product are less than in the reactants.
(d) MgCO 3 (s) â¯â¯
â MgO(s) + CO 2 (g)
Ans.
ÎS is +ve, as disorder increases in the products.
(e) CO 2 (g) â¯â¯
â CO 2 (s)
Ans.
ÎS is âve as disorder decreases in the product.
(f) Cl 2 (g) â¯â¯
â 2Cl(g)
Ans.
ÎS is +ve, as one mole of Cl2(g) gives two moles of Cl(g) atoms and hence, disorder increases.
*12.
What can be said about the spontaneity of reactions when
(a) ÎH and ÎS are both positive.
Reactions become spontaneous at high temperature When T â ÎS > ÎH
(b) ÎH and ÎS are both negative.
Reactions become spontaneous at low temperatures When T â ÎS < ÎH
(c) ÎH is positive and ÎS is negative.
Reactions are nonspontaneous at all temperatures.
(d) ÎH is negative and ÎS is positive.
Reactions are spontaneous at all the temperatures.
Ans.
Ans.
Ans.
Ans.
Unique Solutions Â®
S.Y.J.C. Science - Chemistry - Part I
```
Related documents