Anonymous
Anonymous asked in Science & MathematicsChemistry · 4 months ago

Calculate the amount of heat needed to change 45.0 grams of ice at -25.0 °C to steam at 250.0 °C. ?

Full question: Calculate the amount of heat needed to change 45.0 grams of ice at -25.0 °C to steam at 250.0 °C. (For water, ΔHfus = 333 J/g; ΔHvap = 2260 J/g; Specific Heat (ice) = 2.10 J g-1 K-1; Specific Heat (steam) = 2.00 J g-1 K-1) 

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    First, heat the ice up to 0 C.  A change of 1 degree Celsius is the same as the change of 1 degree Kelvin

    2.10 J/(g * K) * 45 g * 25 K =>

    25 * 45 * 2.10 Joules

    25 * 45 * 2.1 Joules =>

    (100/4) * 45 * 2.1 Joules =>

    45 * 210 / 4 Joules =>

    90 * 210 / 8 Joules =>

    18900 / 8 Joules >

    9450 / 4 Joules =>

    4725 / 2 Joules =>

    2362.5 Joules

    Now calculate how much energy it would take to melt the ice

    45 g * 333 J/g =>

    5 * 9 * 333 Joules =>

    5 * (2700 + 270 + 27) Joules =>

    5 * 2997 Joules =>

    5 * (3000 - 3) Joules =>

    15000 - 15 Joules =>

    14985 Joules

    Now calculate how much energy it would take to heat the water up to 100 C

    4.186 J/(g * K) * 100 K * 45 g =>

    45 * 4.186 * 100 Joules =>

    45 * 418.6 Joules =>

    90 * 209.3 Joules =>

    9 * 2093 Joules =>

    18000 + 810 + 27 Joules =>

    18837 Joules

    Now calculate how much energy it would take to turn the water into steam

    45 g * 2260 J/g =>

    45 * 2260 Joules =>

    90 * 1130 Joules =>

    9 * 113 * 100 Joules =>

    (900 + 90 + 27) * 100 Joules =>

    (900 + 117) * 100 Joules =>

    1017 * 100 Joules =>

    101700 Joules

    Now calculate how much energy it would take to heat the steam another 150 degrees

    45 g * 2 J/(g * K) * 150 K =>

    45 * 2 * 150 Joules =>

    90 * 150 Joules =>

    13500 Joules

    Add them all together

    2362.5 Joules + 14985 Joules + 18837 Joules + 101700 Joules + 13500 Joules =>

    ‭151,384.5‬ Joules

    To 3 sf

    151000 Joules

    To 4 sf

    151400 Joules

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