Consider a Styrofoam cup that contains 500 g of water at 10 C If you add a 500

# Consider a styrofoam cup that contains 500 g of water

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Consider a Styrofoam cup that contains 50.0 g of water at 10.C. If you add a 50.0 g iron ball at 90.C to the water, what is the final temperature of the water?(cH2O= 4.18 J/°C·g and cFe= 0.45 J/°C·gClicker Q4 ) A.Above 90 °CB.Between 50 °C and 90 °CC.50 °CE.Below 10 °CD. Between 10 °C and 50 °C
Consider a Styrofoam cup that contains 50.0 g of water at 10. C. If you add a 50.0 g iron ball at 90. C to the water, what is the final temperature of the water? ( c H2O = 4.18 J/°C·g and c Fe = 0.45 J/°C·g ) Clicker Q4: Solution A. Above 90 °C B. Between 50 °C and 90 °C C. 50 °C E. Below 10 °C D. Between 10 °C and 50 °C -(50.0 g*0.45 J/gdeg)(Tf - 90) = (50 g*4.18J/gdeg)(Tf - 10)
Clicker Q6What is the equilibrium constant (K) at 298K for the reaction: N2(g) + 3H2(g) 2NH3(g) N
Clicker Q6: Solution N
Clicker Q7Consider the reaction N2(g) + 3H2(g) 2NH3(g)at 298K. you start with 0.22 atm N2(g), 0.40 atm H2(g), and 1.2 atm NH3(g), how will the reaction proceed? If N
Clicker Q7: Solution Consider the reaction N 2 (g) + 3H 2 (g) 2NH 3 (g) at 298K. If you start with 0.22 atm N 2 (g), 0.40 atm H 2 (g), and 1.2 atm NH 3 (g), how will the reaction proceed? A. To the right B. To the left C. It is at equilibrium H o f (kJ/mol) G o f (kJ/mol) S o (J/mol K) N 2 (g) 0 0 -191.6 H 2 (g) 0 0 130.7 NH 3 (g) -46.1 -16.5 192.5 ΔG o = 2ΔG o f (NH 3 ) – 3ΔG o f (H 2 ) – 3ΔG o f (N 2 ) = 2(-16.5) – 3(0) – 1(0) = -33 kJ ΔG = ΔG o + RT ln Q
Clicker Q7: Solution Consider the reaction N 2 (g) + 3H 2 (g) 2NH 3 (g) at 298K. If you start with 0.22 atm N 2 (g), 0.40 atm H 2 (g), and 1.2 atm NH 3 (g), how will the reaction proceed? A. To the right B. To the left C. It is at equilibrium H o f (kJ/mol) G o f (kJ/mol) S o (J/mol K) N 2 (g) 0 0 -191.6 H 2 (g) 0 0 130.7 NH 3 (g) -46.1 -16.5 192.5 = -33 kJ ΔG = ΔG o + RT ln Q (1.2) 2 (0.22)(0.4) 3 102.3 + (0.0083)(298)(ln 102.3 ) = -21.5 kJ SPONTANEOUS in the forwards direction as written to the right Q P NH 3 2 P N 2 P H 2 3
Clicker Q8Barium hydroxide is only slightly soluble in water. Is the ΔGfor the reaction: Ba(OH)2(s) + H2O Ba2+(aq) + 2OH‾(aq)positive, negative or zero?
A. Positive B. negative C. zero D. Cannot determine Clicker Q8: Solution Barium hydroxide is only slightly soluble in water. Is the ΔG for the reaction: Ba(OH) 2 (s) + H 2 O Ba 2+ (aq) + 2OH‾(aq) positive, negative or zero? ΔG o = -RT lnK Slightly soluble K is a small number If K <1 (but bigger than 0), ΔG o = -RT ln(<1) ln(<1) = negative numbr ΔG o = positive number

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• Fall '13