Question

consider the following data:

when these two metals are placed in contact, which of the following will take place?
heat will flow from cu to pb because cu is at a higher temperature.
heat will flow from cu to pb because cu has a larger specific heat.
heat will flow from cu to pb because cu has a larger heat capacity.
heat will flow from cu to pb because cu has a larger mass.
no heat will flow in either direction.

Explanation:

To determine heat flow, we calculate heat capacity ($q = mc\Delta T$, but for equilibrium, we compare initial thermal energies or use the fact heat flows from higher temp to lower. First, calculate heat capacity (thermal energy) for each:

• For Pb: $q_{Pb} = m_{Pb}c_{Pb}T_{Pb} = 12 \times 0.128 \times 30 = 46.08$ J (approx, as $\Delta T$ for equilibrium isn't needed yet—initial temp of Cu (60°C) is higher than Pb (30°C). Heat flows from higher temperature to lower temperature. Let's check heat capacity (total thermal energy) too:
• $q_{Pb} = 12 \times 0.128 \times 30 = 46.08$ J
• $q_{Cu} = 30 \times 0.385 \times 60 = 693$ J

Cu has higher temp (60°C > 30°C) and higher thermal energy. But the key reason for heat flow direction is temperature difference: heat flows from higher temp to lower temp. Now, analyze options:

1. "Heat will flow from Cu to Pb because Cu is at a higher temperature." — Correct, as heat flows from higher $T$ to lower $T$.
2. Specific heat (0.385 > 0.128) doesn’t determine direction (it’s about temp difference).
3. Heat capacity ($q_{Cu} > q_{Pb}$) is a result, but direction is due to temp, not heat capacity magnitude.
4. Mass (30 > 12) doesn’t determine direction (temp is key).
5. No heat: False, as temps differ (60 ≠ 30).

Answer:

A. Heat will flow from Cu to Pb because Cu is at a higher temperature.