Predict the sign of the entropy change, delta s, for each of the following reactions: the signs are either going to be pos or negativea) pb^2+(aq) + 2cl-(aq) > pbcl2(s)b) caco3(s) > cao(s) + co2 (g)c) 2nh3(g) > n2(g) + 3h2(g)d) p4(g) + 5o2(g) > p4o10(s)e) c4h8(g) + 6o2(g) > 4co2(g) + 4h2o(g)f) i2(s) > i2(g)

a) :  negative

b)   : positive

c) : positive.

d) : negative

e) :  positive.

f) : positive.

Explanation:

Entropy is the measure of randomness or disorder of a system. If a system moves from  an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

is positive when randomness increases and is negative when randomness decreases.

a)

As ions are moving to solid form , randomness decreases and thus sign of is negative.

b)

As solid is changing to gas, randomness increases and thus sign of is positive.

c)

As 2 moles of reactants are converted to 4 moles of products , randomness increases and thus sign of is positive.

d)

As gas is changing to solid, randomness decreases and thus sign of is negative.

e)

As 7 moles of reactants are converted to 8 moles of products , randomness increases and thus sign of is positive.

f)

As solid is changing to gas, randomness increases and thus sign of is positive.

b is the correct