Answer:
What is the amount of energy needed to change 20g of ice at 0°C to steam at 100°C?
A mattress you can fall back on.
Use the formula
q = m·ΔHf
where q = heat energy; m = mass; ΔHf = heat of fusion
q = (20 g)x(334 J/g)
q = 6680 J
Step 2: Heat required to raise the temperature of 0 °C water to 100 °C water
q = mcΔT
q = (20 g)x(4.18 J/g·°C)[(100 °C - 0 °C)]
q = (20 g)x(4.18 J/g·°C)x(100 °C)
q = 8360 J
Heat required to raise the temperature of 0 °C water to 100 °C water = 8360 J
Heat required to convert 100 °C water to 100 °C steam
q = m·ΔHv
where q = heat energy; m = mass; ΔHv = heat of vaporization
q = (20 g)x(2257 J/g)
q = 45140 J
Heat required to convert 100 °C water to 100 °C steam = 45140 J
Total energy required: 6680+8360+45140=60180 Joules
Or practically understanding it: about 20s in a 3000W kettle.