Question

An ice-cube tray is filled with 75.0 g of water. After the filled tray the following es an equilibrium temperature 20.0 ᵒC , it is placed in a freezer set at -8.00 ᵒC to make ice cubes. Calculate the energy that must be removed from the water to make ice cubes at -8.00 ᵒC .

Answer 1

To make ice cubes at -8.00 °C, the energy that must be removed from the water is approximately 6736.6 J.

Step-by-step explanation:

To calculate the energy that must be removed from the water to make ice cubes at -8.00 °C, we need to consider the heat absorbed in three steps:

Heating the ice from -8.00 °C to 0.00 °C: Q₁ = mass of ice × specific heat of ice × temperature change = 75.0 g × 2.062 J/(g°C) × 8.00 °C = 9.85 J.

Melting the ice at 0.00 °C: Q₂ = mass of ice × enthalpy of fusion of ice = 75.0 g × 6.01 kJ/mol = 450.75 J.

Cooling the water from 20.0 °C to 0.00 °C: Q₃ = mass of water × specific heat of water × temperature change = 75.0 g × 4.184 J/(g°C) × 20.0 °C = 6276 J.

The total energy to be removed is the sum of the three heats: Q = Q₁ + Q₂ + Q₃ = 9.85 J + 450.75 J + 6276 J = 6736.6 J (rounded to four significant figures).

Answer 2

To calculate the energy that must be removed from the water to make ice cubes at -8.00°C, we need to consider the heat lost during the cooling and freezing processes.

Step-by-step explanation:

To calculate the energy that must be removed from the water to make ice cubes at -8.00°C, we need to consider the heat lost during the cooling and freezing processes. First, we need to bring the ice up to 0°C and melt it. The heat (Q₁) required for this can be calculated using the equation Q = m * c * ΔT, where m is the mass of the ice, c is its specific heat capacity, and ΔT is the temperature change. Next, we need to determine the heat lost by the hot water, which equals the heat gained by the cold water. This can be calculated using the equation Q = m * c * ΔT, where m is the mass of the hot water, c is its specific heat capacity, and ΔT is the temperature change. By equating the two equations, we can solve for the heat gained by the cold water and hence determine the energy that must be removed from the water.