The calorimeter contains 5 kg of ice at a temperature of -20 ° C. Then 0.5 kg of water is poured into the calorimeter, the temperature of which is + 10 ° C. Heat exchange with the environment can be neglected. Choose two correct statements from the suggested list. Specify their numbers. (The specific heat of ice is 2100 J / (kg ·°C), the specific heat of water is 4200 J/(kg·°C), the specific heat of melting of ice is 3.3·105 J/kg). 1) In a state of thermal equilibrium, all the matter in the calorimeter will be in a liquid state. 2) When thermal equilibrium is reached, the water temperature will decrease by 5 °C. 3) In a state of thermal equilibrium, all the matter in the calorimeter will be in a solid state. 4) When thermal equilibrium is reached, there will be a mixture of water and ice in the calorimeter. 5) In a state of thermal equilibrium, the temperatures of initially solid and initially liquid substances will be equal.

Expert:

Warmer water will give off heat to increase the temperature of the ice, then, if there is enough heat, then all the ice will turn into a liquid, if not, then two states are possible: when only ice is in the calorimeter after thermal equilibrium is established, or there is a mixture of ice and water. Let's compare the heat that water can give off while in a liquid state with the heat needed to melt all the ice:

Q1 = 18600000 joule

Q2= 21000 joule

where m_1, in the substitution from to m_2 are the initial masses of ice and water, respectively, t_1,in the substitution from to t_2 are the initial temperatures of ice and water, respectively, c_1, in the substitution from to c_2 are the specific heat of ice and water, respectively, t_0 is the melting point of ice equal to 0 °C. We see that Q_1 is greater than Q_2, that is, it will not be possible to melt all the ice. Now, let's assume that, on the contrary, all the water has turned into a solid state:

The heat Q_1' is greater than the heat Q_2', respectively, all the water will turn into ice, while all the ice will remain in a solid state. The water temperature will decrease by more than 5 °C. In a state of thermal equilibrium, the temperatures of substances with initially different temperatures are equalized.

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