Hvap 40.65 kJ/mol
Hf -285.83 kJ/mol
Hfusion 6.03 kJ/mol
specific heat 4.186 J/gC
molar mass 18.02 g
How much energy is consumed by thawing 4.3 g ice?
If the ice is at zero C, then 4.3 x(1 mol/18 g) x 6.03 kJ/mol = ?kJ.
To calculate the amount of energy consumed by thawing 4.3 g of ice, we need to consider the heat required for three processes: raising the temperature of the ice from its initial temperature to its melting point, melting the ice at its melting point, and raising the temperature of the resulting liquid water to the final temperature.
Here's how we can calculate it step by step:
Step 1: Calculate the heat required to raise the temperature of the ice to its melting point.
The specific heat capacity of ice is given as 4.186 J/g°C. We also know the initial temperature of the ice (assumed to be 0°C) and the melting point (0°C).
The formula to calculate the heat required to raise the temperature is:
Heat = mass × specific heat × temperature change
In this case, the mass is 4.3 g, the specific heat is 4.186 J/g°C, and the temperature change is (0°C - 0°C) = 0°C. Since there is no temperature change, the heat required in this step is 0J.
Step 2: Calculate the heat required to melt the ice.
The enthalpy of fusion (Hfusion) is given as 6.03 kJ/mol. To convert from grams to moles, divide the mass of the ice by its molar mass.
The molar mass of water (H2O) is approximately 18.02 g/mol. Therefore, the number of moles of ice is:
Moles = mass / molar mass
Moles = 4.3 g / 18.02 g/mol
≈ 0.2386 mol
The heat required to melt the ice is given by:
Heat = moles × Hfusion
Heat = 0.2386 mol × 6.03 kJ/mol
≈ 1.44 kJ
Step 3: Calculate the heat required to raise the temperature of the resulting liquid water to the final temperature.
We need to raise the temperature of the liquid water from the melting point (0°C) to the final temperature (not given in the question). Let's assume the final temperature is 25°C.
Using the same formula as in Step 1, the heat required is:
Heat = mass × specific heat × temperature change
The mass is still 4.3 g, the specific heat is 4.186 J/g°C, and the temperature change is (25°C - 0°C) = 25°C.
Heat = 4.3 g × 4.186 J/g°C × 25°C
≈ 452.545 J
Step 4: Calculate the total heat required.
To find the total heat required, add up the heats calculated in each step:
Total Heat = Heat from Step 1 + Heat from Step 2 + Heat from Step 3
Total Heat = 0 J + 1.44 kJ + 452.545 J
≈ 1444.545 J
Therefore, approximately 1444.545 J of energy is consumed by thawing 4.3 g of ice.