A copper block of mass 3 kg is heated in a furnace to a temperature of 450° C and then placed on a large ice block. Find the maximum amount of ice that can melt? (specific heat of copper = 0.39 Jg-1K-1, heat of fusion of water = 335 Jg-1K-1)
1.57 kg
This problem involves the fundamental principle of heat transfer, where thermal energy is exchanged between objects at different temperatures. Specifically, the heat lost by the hot copper block is absorbed by the ice, causing it to melt.
When a hot copper block is placed on an ice block, the copper block will release its thermal energy, cooling down until it reaches the melting point of ice, which is 0°C. This released heat energy is then absorbed by the ice, causing a portion of it to change from a solid state to a liquid state (melt) without a change in temperature (as long as both ice and water coexist at 0°C).
First, we need to calculate the total amount of heat energy released by the copper block as it cools from 450°C to 0°C.
Using the formula: $$Q_{\text{lost}} = m_{\text{copper}} \times c_{\text{copper}} \times \Delta T_{\text{copper}}$$
Substitute the given values into the formula:
$$Q_{\text{lost}} = 3000\text{ g} \times 0.39\text{ Jg}^{-1}\text{K}^{-1} \times 450\text{ K}$$
$$Q_{\text{lost}} = 1170\text{ J K}^{-1} \times 450\text{ K}$$
$$Q_{\text{lost}} = 526500\text{ J}$$
Now, this heat energy lost by the copper block is completely absorbed by the ice to melt it. We can use the latent heat of fusion formula to find the mass of ice melted.
The formula for heat absorbed by ice to melt is: $$Q_{\text{gained}} = m_{\text{ice}} \times L_f$$
Since \(Q_{\text{lost}} = Q_{\text{gained}}\), we can set up the equation:
$$526500\text{ J} = m_{\text{ice}} \times 335\text{ Jg}^{-1}$$
To find the mass of ice melted (\(m_{\text{ice}}\)), rearrange the equation:
$$m_{\text{ice}} = \frac{526500\text{ J}}{335\text{ Jg}^{-1}}$$
$$m_{\text{ice}} = 1571.64179\dots \text{ g}$$
To express the mass in kilograms, divide by 1000:
$$m_{\text{ice}} = \frac{1571.64179\dots \text{ g}}{1000\text{ g/kg}}$$
$$m_{\text{ice}} \approx 1.5716\text{ kg}$$
The maximum amount of ice that can melt due to the heat transferred from the copper block is approximately 1.57 kg.
Which of the following statements is INCORRECT for heat?