Question

1) a molecule f O_3 has less motional energy than a molecule of F_2

a/ true

b/false

2)for two substances in the same phase and with similar molar masses the substance with the less complex molar structure has the greater standard entropy.

a/true

b/false

3)which of the following processes causes an entropy decrease?

a/the reaction of vinegar and baking soda to form carbon dioxide.

b/sublimation of dry ice.

c/dissolving solid NaCl in water

d/melting ice to form water

Answer 1

1)

false, O3 has higher mass, therefore, will have more enery in the same velocity

E = 1/2*m*V^2

if we choose the same velocity for each material, then the only thing that changes in the equation is the mass; higher mass, higher energy.

MW O3 = 48 g/mol

MW F2 = 38 g/mol

2)

TRUE; since the entropy of making a complex structure implies to ORDER; therefore, it must be very entropic

3)

a/the reaction of vinegar and baking soda to form carbon dioxide. -->

NaHCO3 + CH3COOH = NaCH3COO (aq) + H2O(l) + CO2(g)

2 mol react to form 3 mol

there is gas formation so this must be an INCREASE in entropy

b/sublimation of dry ice.

sublimation is essentially a solid that goes directly to a gas, gas has a high entropy value so this will be an INCREASE in entropy

c/dissolving solid NaCl in water --> NaCl is a very ordered crystal array; therefore, when dissolving, you are destroying (i.e. disordering) the substances... This must be a high/increase in entropy

d/melting ice to form water ---> melting is changing a solid to liquid, liquid has much more entropy than a solid therefore, this is an INREASE in entropy

there is not a single process in the list that will form a DECREASE in enetropy