Question

How much heat is required to convert 90 g of ice at - 40.0°C into water at 60.0°C? The specific heats (Cs) of ice, water, and steam are 2.09 J/gK, 4.18 J/gK, and 1.84 J/gK, respectively. For H0 AH A) 60.1 kJ = 6.01 kJ/mol, and AH B) 18.8 kJ -40.67 kJ/mol. C) 45.1 kJ D) 37.6 kJ E) 30.5 kJ 11. What is correct for a triple point on phase diagram? A) a triple point shows temperature and pressure, when properties of liquid and gas are the same B) a triple point shows temperature and pressure of conversion from liquid to gas (C) a triple point shows conditions where solid, liquid and gas are in equilibrium D) a triple point shows temperature and pressure of conversion from solid to liquid E) a triple point shows temperature and pressure of conversion from solid to gas 12. Which phase transformation of the same substance has the lowest absolute value of AH°? a) sublimation b) condensation c) freezing d) vaporization e) deposition tion? 13. For H20, AH melting = 6.02 kJ/mol; AH condensation=-40.7 kJ/mol. What is AHi a) 34.68 kJ/mol b)-34.68 kJ/mol c) 40.7 kJ/mol d) -46.72 kJ/mol e) 46.72 kJ.mol 14. How much heat is needed to convert 180 g of ice into water at 0°C? (For water Hºm = 6.08 kJ/mol.) a) 60.8 kJ b) 1.216 kJ c) 30.4) d) 547 J e) -547 J 15. How much heat is needed to convert 180 g of water into vapor at 100°C? (For water AH". = 40.7 kJ/mol.) a) 60.8 kJ b) 1.216 kJ c) 30.4J d) 407 k.) e) -407J

if u can show how u do each one, that would be amazing!

Answer 1

(10) Mass of water, m= 90 g molar mass of water, M = 18.0 g/mol (1) energy from -40°Сto 0°C Change in temperature, AT = 0°C-(-40°C) = 40°C Qı = mCAT = 90.09x2.09 -x40°C or K = 7524 Jx 1kJ 1000 J = 7.51J (2) heat of fusion solid to liquid) Qy = MAHA = 90.0 gx6.01 kJmolx mod = 30 kJ (3) energy from 0°C to 60°C Change in temperature, AT = 60°C-(0°C)= 60°C Q. = mC.AT = 90.0gx4.18 -*_x60°C or K gK = 22572Jx 1kJ 1000J = 22.6 kJ The total heat required from -40 °C to 40 °Cis Q= Q,+Q, +Q3 = 7.5kJ + 30.0 kJ+ 22.6 kJ = 60.1kJ Therefore, the correct option is A

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(11) A triple point in the phase di gram is the point at which all the phases of a substance meets. So the triple point represents the conditions where all the phases of the substance are in equilibrium. Therefore, the corret option is c - - - - - - - - - - - - - - - - - - - - - - - - - - - (12) There are three fundamental phases for a substance. They are Solid, liquid and gas. Among these phases the substance transfers from one phase to another The following are the phase transfers of a substance. Melting from solid to liquid Freezing From liquid to solid evaporating: From liquid to gas condensing: From gas to Liquid Sublimation: From solid to gas deposition: From gas to solid Solid Meling Liquid proting gas deposition Solid cordersing Among all the phase transfers Freezing has the lowest absolute value of AH. Therefore, the corret option is c

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (13) Given, AH Meting = 6.02 kJ/mol and AH Cordering = -40.7 kJ/mol Relation between heats of melting, condensation and sublimation is AH ublim ation = AH Maling - AH carensing Substitute the corresponding value sin the above equation to calcualte the heat of sublimation. AH ubilin stiai = 6.02 kJ/mol -(-40.7 kJ/mol) AH sublin stion = 46.72 kJ/mol Therefore, the corret option is e ------------------------------------------------- (14) Mass of water, m= 180 g molar mass of water, M = 18.0g/mol heat of fusion (solid to liquid) Q = MAH., = 180 g *6.08 kJ/mol x-mol * 18.0g = 60.8 kJ Therefore, the corret option is a -------------------------------------------- (15) heat of vaporisation (liquid to gas) Q = mAH = 180 gx40.7 kJ/molx mol = 407 kJ Therefore, the corret option is a