Here is a worked example but i can\'t get the right answer to the practice be

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Here is a worked example but i can't get the right answer to the practice below.
 Problem A 5.00-kg block of ice at 0°C is added to an insulated container partially filled with 10.0 kg of water at 15.0°C. (a) Find the final temperature, neglecting the heat capacity of the container. (b) Find the mass of the ice that was melted. Strategy Part (a) is tricky because the ice does not entirely melt in this example. When there is any doubt concerning whether there will be a complete phase change, some preliminary calculations are necessary. First, find the total energy required to melt the ice, Qmelt, and then find Qwater, the maximum energy that can be delivered by the water above 0°C. If the energy delivered by the water is high enough, all the ice melts. If not, there will usually be a final mixture of ice and water at 0°C, unless the ice starts at a temperature far below 0°C, in which case all the liquid water freezes. SOLUTION (a) Find the equilibrium temperature. First, compute the amount of energy necessary to completely melt the ice: Qmelt = miceLf = (5.00 kg)(3.33 105 J/kg) = 1.67 106 J Next, calculate the maximum energy that can be lost by the initial mass of liquid water without freezing it. Qwater = mwatercΔT = (10.0 kg)(4190 J/kg · °C)(0°C − 15.0°C) = −6.29 105 J This result is less than half the energy necessary to melt all the ice, so the final state of the system is a mixture of water and ice at the freezing point. T = 0°C (b) Compute the mass of ice melted. Set the total available energy equal to the heat of fusion of m grams of ice, mLf , and solve for m. 6.29 105 J = mLf = m(3.33 105 J/kg) m = 1.89 kg LEARN MORE Remarks If this problem is solved assuming (wrongly) that all the ice melts, a final temperature of T = −16.5°C is obtained. The only way that could happen is if the system were not isolated, contrary to the statement of the problem. In the exercise, you must also compute the thermal energy needed to warm the ice to its melting point. ========================================================================== PRACTICE IT
 Use the worked example above to help you solve this problem. A 4.95 kg block of ice at 0°C is added to an insulated container partially filled with 10.6 kg of water at 15.0°C.
 (a) Find the final temperature, neglecting the heat capacity of the container. °C (b) Find the mass of the ice that was melted. Answer in ......... kg If 8.80 kg of ice at -5.00°C is added to 12.0 kg of water at 30°C, compute the final temperature. T = ???°C How much ice remains, if any? m = ?????? kg

Explanation / Answer

mass of water mw = 10.6 kg , mass of the ice mice = 4.95 kg

let the final temperature be t
heat lost by water Q1 = mws(15-t)
heat gained by ice = [miceLmelting + mice s(t-0)] ( Lmelting = 2100 J/kg.K , s = 4190 J/kg.K)

10.6 * 4190 * (15-t) = [4.95 * 2100 + 4.95 * 4190 * t ]

solving we get

t = 9.90 C

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