Final answer:
To calculate the energy needed to melt sodium from 200.0 °C to 75.0 °C, we need to consider the different steps involved. First, calculate the heat needed to raise the temperature from the melting point of sodium to the final temperature. Then, determine the heat required to melt sodium at its melting point. Next, calculate the heat released as sodium cools from 200.0 °C to 75.0 °C. Finally, find the total energy needed to complete the process.
Step-by-step explanation:
To calculate the energy needed to melt 20 g of sodium (Na) from 200.0 °C to 75.0 °C, we need to consider the different steps involved.
A) Calculate the heat needed to raise the temperature from 97.8⁰C to 200.0⁰C:
First, we calculate the heat needed to raise the temperature from the melting point of sodium (97.8 °C) to the final temperature of 200.0 °C. We use the equation:
q = m × C × ΔT
where q is the heat energy, m is the mass, C is the specific heat capacity, and ΔT is the change in temperature.
Using the given information, we can substitute the values into the equation and solve for q.
B) Determine the heat required to melt sodium at its melting point:
To determine the heat required to melt sodium at its melting point, we use the equation:
q = m × ΔH
where q is the heat energy, m is the mass, and ΔH is the enthalpy of fusion.
C) Calculate the heat released as sodium cools from 200.0⁰C to 75.0⁰C:
To calculate the heat released as sodium cools from 200.0 °C to 75.0 °C, we use the same equation as in part A, but with a negative value for ΔT because the temperature is decreasing.
D) Find the total energy needed to complete the process:
The total energy needed to complete the process is the sum of the energy calculated in parts A, B, and C.