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30 October, 10:19

How many joules of energy are needed to change 37.5g of ice at 0.00 oC to water at 45.0oC?

(Heat of fusion = 335J/g,

Specific heat of liquid water = 4.184J/g. oC,

Heat of vaporization = 2259 J/g

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Answers (2)
  1. 30 October, 11:43
    0
    19,623 J or 19.6 kJ of heat is needed to change ice at 0°C to water at 45°C

    Explanation:

    To calculate the energy needed to change 37.5g of ice at 0°C to water at 45.0°C, we obtain the individual values of energy needed to convert the ice from 0° to water at 0 °C and the value of energy needed to convert the water from 0 °C to water at 45°C and then add the values together.

    Heat (q) = mΔHf + mCpΔT

    So;

    1. heat needed to change from solid to liquid = m ΔHf

    q = 37.5 * 335

    q = 12,562.5 Joules

    2. heat needed to convert the water at 0C to water at 45 C

    q = mcΔT

    q = 37.5 * 4.184 * (45-0)

    q = 37.5 * 4.184 * 45

    q = 7,060.5 J

    The heat needed to change the ice to water at 45 C = 12, 562.5 + 7.060.5 = 19,623 J or 19.6 kJ of heat.
  2. 30 October, 13:59
    0
    We need 19620 joules

    Explanation:

    Step 1: Data given

    Mass of ice = 37.5 grams

    Temperature of ice = 0.00 °C

    Final temperature of water = 45.0°C

    (Heat of fusion = 335J/g,

    Specific heat of liquid water = 4.184J/g°C

    Heat of vaporization = 2259 J/g

    Step 2: Calculate the energy needed to melt ice to water at 0°C

    Q = m*ΔHfus

    Q = 37.5 grams * 335J/g

    Q = 12562.5 J = 12.56 kJ

    Step 3: Calculate energy needed to heat water from 0 to 45 °C

    Q = m*c*ΔT

    ⇒with Q = the enegy needed to heat water from 0 to 45 °C

    ⇒with m = the mass of water = 37.5 grams

    ⇒with ΔT = the change of temperature = 45 °C

    ⇒with c = the specific heat of water = 4.184 J/g°C

    Q = 37.5g * 4.184 J/g°C * 45 °C

    Q = 7060.5 J = 7.06 kJ

    Step 4: Calculate the total heat needed

    Total heat = 12.56 kJ + 7.06 kJ

    Total heat = 19.62 kJ = 19620 J

    We need 19620 joules
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