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entropy13 (Points: 8.33) Consider each of the following reactions and decide whe

ID: 689581 • Letter: E

Question

entropy13

(Points: 8.33)

Consider each of the following reactions and decide whether thestandard entropy change for the reaction will be, (a) Large &positive; or (b) Small; or (c) Large & negative.


Matching pairs

NH3 (g) + HCl (g) = NH4Cl (s)

- Select choice -negativepositivevery close to zero

Cu (s) + 2 H2SO4 (aq) = CuSO4(aq) + 2 H2O (l) + SO2 (g)

- Select choice -negativepositivevery close to zero

C6H12O6 (s) + 6 O2(g) = 6 CO2 (g) + 6 H2O (l)

- Select choice -negativepositivevery close to zero

BaSO4 (s) + 2 H2O (g) =BaSO4.2H2O (s)

- Select choice -negativepositivevery close to zero

2 Na (l) + H2 (g) = 2 NaH (s)

- Select choice -negativepositivevery close to zero

Mg (s) + CO2 (g) = MgO (s) + CO (g)

- Select choice -negativepositivevery close to zero

entropy13

(Points: 8.33)

Consider each of the following reactions and decide whether thestandard entropy change for the reaction will be, (a) Large &positive; or (b) Small; or (c) Large & negative.


Matching pairs

NH3 (g) + HCl (g) = NH4Cl (s)

- Select choice -negativepositivevery close to zero

Cu (s) + 2 H2SO4 (aq) = CuSO4(aq) + 2 H2O (l) + SO2 (g)

- Select choice -negativepositivevery close to zero

C6H12O6 (s) + 6 O2(g) = 6 CO2 (g) + 6 H2O (l)

- Select choice -negativepositivevery close to zero

BaSO4 (s) + 2 H2O (g) =BaSO4.2H2O (s)

- Select choice -negativepositivevery close to zero

2 Na (l) + H2 (g) = 2 NaH (s)

- Select choice -negativepositivevery close to zero

Mg (s) + CO2 (g) = MgO (s) + CO (g)

- Select choice -negativepositivevery close to zero

Explanation / Answer

The Entropy of a substance is a measure of its "disorder." Thegreater the disorder, the greater the entropy. In general, a gas ismore disordered (higher entropy) then a liquid, which is moredisordered than a solid. Ions in aqueous solution are normally moredisordered than in their solid salt. S is the change inentropy (entropy of products minus entropy of reactants). NH3 (g) + HCl (g) -> NH4Cl (s) Here we are going from gas to solid (less disorder) thusnegative entropy. Cu (s) + 2 H2SO4 (aq) -> CuSO4(aq) + 2 H2O (l) + SO2 (g) Here we are going from solid and aqueous to aqueous, liquid and gas(more disorder), positiveentropy. C6H12O6 (s) + 6 O2 (g)-> 6 CO2 (g) + 6 H2O (l) Here the 6 moles of gas to gas cancel, so we observe the solidgoing to liquid, positiveentropy. BaSO4 (s) + 2 H2O (g) ->BaSO4.2H2O (s) Here we are going from solid and gas to less disorder solid.Negative entropy. 2 Na (l) + H2 (g) -> 2 NaH (s) Here we are going from liquids and gas to solid, less disorder,negative entropy. Mg (s) + CO2 (g) = MgO (s) + CO (g) Here we are going from solid and gas to solid and gas, entropy isvery close to zero. Hope this helped :)