Regents WarmUp Which two characteristics are associated with

Regents Warm-Up Which two characteristics are associated with metals? (1) low first ionization energy and low electronegativity (2) low first ionization energy and high electronegativity (3) high first ionization energy and low electronegativity

ENTROPY AIM: What is ENTROPY? DO NOW: What are the oxidation #s in 1) HOBr 2) KCl. O 3

ENTROPY • ENTROPY (DS): a measure of the randomness or disorder in a system. • A system with more disorder has a greater entropy • What are some examples of entropy?

ENTROPY • Phase changes are changes in the entropy of the molecules • solid liquid gas ------ENTROPY • Entropy increases as disorder of molecules increases

ENTROPY • Changes occur so the • For a reaction, when the highest possible entropy amt of gas being produced is reached. h the overall entropy will • Increases in entropy favor h SPONTANEOUS RXNS • Example: • Does dissolving a gas in a SO 3(g) 2 SO 2(g) + O 2(g) liquid (soda) increase or • Solutions h in entropy decrease entropy? when something is added This causes a i in entropy • h in temp will h entropy

ENTROPY Which sample has the greatest entropy? 1. NH 3(g) 2. NH 3(s) 3. NH 3(l) 4. NH 3(aq) Which process is accompanied by a decrease in entropy? 1. boiling of water 2. subliming of iodine 3. condensing of water vapor 4. melting of ice

ENTROPY • Entropy h when: 1. 2. 3. 4. a solid becomes a gas a solid becomes a liquid becomes a gas Something is broken into smaller pieces • In our bodies the desire to become disordered is counteracted by all the energy and heat we produce • Therefore, changes in entropy(DS) and enthalpy (DH) can tell us if a reaction will be spontaneous

ENTROPY • A system tends to change toward lower enthalphy and higher entropy • Spontaneous reactions occur naturally and favor product formation • Some reactions may depend on conditions for example: C 6 H 12 O 6(s) CO 2(g)+H 2 O(g) • Some endothermic reactions are spontaneous due to an h in entropy (ex. ice melting) • h in entropy favors spontaneous reactions

ENTROPY As carbon dioxide sublimes, its entropy Which sample has the lowest entropy? 1. decreases 2. Increases 3. remains the same 1. 2. 3. 4. KNO 3(l) KNO 3(s) H 2 O(l) H 2 O(g)

ENTROPY At STP, a sample of which element has the highest entropy? 1. Na(s) 2. Br 2(l) 3. Hg(l) 4. F 2(g) Which list of the phases of H 2 O is arranged in order of increasing entropy? 1. ice, steam, and liquid water 2. steam, liquid water, and ice 3. ice, liquid water, and steam 4. steam, ice, and liquid water