Quantity | per gram | per mole |
Enthalpy of fusion | 333.6 J/g | 6010. J/mol |
Enthalpy of vaporization | 2257 J/g | 40660 J/mol |
Specific heat of solid H2O (ice) | 2.087 J/(g·°C) * | 37.60 J/(mol·°C) * |
Specific heat of liquid H2O (water) | 4.184 J/(g·°C) * | 75.37 J/(mol·°C) * |
Specific heat of gaseous H2O (steam) | 2.000 J/(g·°C) * | 36.03 J/(mol·°C) * |
At 1 atm, how much energy is required to heat 49.0 g of H2O(s) at − 18.0 °C to H2O(g) at 135.0 °C? Heat transfer constants can be found in this table.
Ti = -18.0 oC
Tf = 135.0 oC
here
Cs = 2.087 J/goC
Heat required to convert solid from -18.0 oC to 0.0 oC
Q1 = m*Cs*(Tf-Ti)
= 49 g * 2.087 J/goC *(0--18) oC
= 1840.734 J
Lf = 333.6 J/g
Heat required to convert solid to liquid at 0.0 oC
Q2 = m*Lf
= 49.0g *333.6 J/g
= 16346.4 J
Cl = 4.184 J/goC
Heat required to convert liquid from 0.0 oC to 100.0 oC
Q3 = m*Cl*(Tf-Ti)
= 49 g * 4.184 J/goC *(100-0) oC
= 20501.6 J
Lv = 2257.0 J/g
Heat required to convert liquid to gas at 100.0 oC
Q4 = m*Lv
= 49.0g *2257.0 J/g
= 110593 J
Cg = 2.0 J/goC
Heat required to convert vapour from 100.0 oC to 135.0 oC
Q5 = m*Cg*(Tf-Ti)
= 49 g * 2 J/goC *(135-100) oC
= 3430 J
Total heat required = Q1 + Q2 + Q3 + Q4 + Q5
= 1840.734 J + 16346.4 J + 20501.6 J + 110593 J + 3430 J
= 152712 J
= 152.7 KJ
Answer: 152.7 KJ
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