What is the total energy change if 150.0 grams of ice at 0.0 oC are melted, then the water is warmed to 45.0 oC? Is this process endothermic or exothermic? ƒ´Hf = 6.01 kJ/mol(multiple steps)
q1 to melt ice solid to liquid water at zero C. .
q1 = mass ice x heat fusion
q2 to warm liquid water from zero to 45 C.
q21 = mass H2O x specific heat H2O x (T final-T initial)
Total = q1 + q2
To calculate the total energy change, we need to consider two processes: the energy required to melt the ice and the energy required to warm the water.
First, we need to determine the amount of heat required to melt the ice. The heat required to melt a substance is given by the equation Q = m × ΔHf, where Q is the heat, m is the mass, and ΔHf is the heat of fusion.
Since the given value is ΔHf in kilojoules per mole, we need to convert the mass of the ice into moles in order to use this value. The molar mass of water (H2O) is approximately 18.02 g/mol. Hence, the number of moles of ice can be calculated as follows:
moles of ice = mass of ice / molar mass of water
= 150.0 g / 18.02 g/mol
Once you have the number of moles of ice, multiply it by the heat of fusion (ΔHf) to calculate the heat required to melt the ice.
Next, we need to determine the amount of heat required to warm the water from 0.0 oC to 45.0 oC. The heat required to increase the temperature of a substance is given by the equation Q = m × c × ΔT, where Q is the heat, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature.
The specific heat capacity of water is approximately 4.18 J/g·°C. However, we need to convert this value to kJ/g·°C to match the given ΔHf units. Hence, the specific heat capacity is 0.00418 kJ/g·°C.
Using this specific heat capacity, we can now calculate the heat required to warm the water from 0.0 oC to 45.0 oC using the formula Q = m × c × ΔT.
Finally, to determine the total energy change, add the heat required to melt the ice to the heat required to warm the water.
After calculating the total energy change, we can determine if the process is endothermic or exothermic. If the total energy change is positive, the process is endothermic because it requires energy input. If the total energy change is negative, the process is exothermic because it releases energy.
By following these steps and performing the necessary calculations, you can find the total energy change and identify if the process is endothermic or exothermic.