Calculate the energy required to change the temperature of 256.7 mL of water at 22.0 degrees celsius to ice at a temperature of -25.5 degrees celsius.
It also tells me to look up the heat of fusion and specific heat. I don't know what I need the heat of fusion for exactly. Please help!
The question is worded funny. You don't need energy "required" since moving T from 22 C to ice at minus whatever removes heat, not adds heat. Anyway,
q1 = heat removed to change T of liquid water @ 22 C to liquid water at zero C.
q1 = mass H2O x specific heat liquid water x (Tfinal-Tinitial)
q2 = heat removed to change liquid water at zero C to solid at zero C. This is why you need the heat of fusion.
q2 = mass H2O x heat fusion.
q3 = heat removed to change T of ice at zero C to -25.5 C.
q = mass ice x specific heat solid ice x (Tfinal-Tinitial)
Total energy removed is q1 + q2 + q3.
The mass of the ice should be the same as the mass of the H2O right?
To calculate the energy required to change the temperature of water from 22.0°C to ice at -25.5°C, you would need to consider two processes: first, you need to lower the temperature of water from 22.0°C to 0°C, and then you need to freeze the water at 0°C to form ice at -25.5°C.
To perform these calculations, you would need to consider two specific heat values: the specific heat capacity of water, which measures the amount of energy required to raise or lower the temperature of water, and the heat of fusion, which measures the energy required to change a substance from a solid to a liquid or vice versa.
Here's how you can calculate the energy required to change the temperature of water to ice:
1. Calculate the energy required to lower the temperature of water from 22.0°C to 0°C:
- The specific heat capacity of water is typically around 4.18 J/g°C.
- Convert the volume of water to grams by multiplying it by the density of water, which is about 1 g/mL.
- Multiply the mass of water in grams by the specific heat capacity of water and the temperature change (ΔT = Tf - Ti).
- This will give you the energy required to lower the temperature of water to 0°C.
2. Calculate the energy required to freeze the water at 0°C to form ice at -25.5°C:
- The heat of fusion for water is approximately 334 J/g.
- Multiply the mass of water in grams by the heat of fusion.
- This will give you the energy required to freeze the water.
3. Add the energies calculated in steps 1 and 2 to determine the total energy required to change the temperature of water at 22.0°C to ice at -25.5°C.
It is important to note that the specific heat capacity and heat of fusion values provided here are approximate values, and it's always a good practice to verify them from a reliable source or the resources provided to you.
Using these calculations and the provided values, you should be able to determine the energy required to change the temperature of water to ice.