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◉When water is heated, the temperature eventually reaches a constant
value and forms a plateau on the graph. What does the plateau indicate?
Answer: The boiling point
◉175 g of water was heated from 15 degree celsius to 88 degree celsius.
How many kilojoules were absorbed by the water? Answer: heat =
mass⋅SH⋅ΔT
ΔT = (Tf - Ti) --> (88-15) = 73 degree celsius
175 g x 73 C x 4.184 J/g∘C = 53,450.6 J
53,450.6 J ÷ 1000 =53.45 kJ
2 sig figs (because ΔT = 73 has 2 sig figs).
53 kJ absorbed
◉How many kilojoules are required at 0 degree celsius to melt an ice
cube with a mass of 25g? Answer: heat =mass⋅Hfus
25 × 334 =8350 J