How much heat is needed to change 4.5g of water at 10degrees celcius into steam at 150 degrees celcius?
To calculate the amount of heat needed to change the temperature of water from 10 degrees Celsius to steam at 150 degrees Celsius, we need to consider two separate processes: heating the water to its boiling point and then boiling it to form steam.
First, let's calculate the heat required to raise the temperature of the water from 10 degrees Celsius to its boiling point at 100 degrees Celsius:
Q1 = mass × specific heat capacity × temperature change
Q1 = 4.5 g × 4.18 J/g°C × (100°C - 10°C)
Q1 = 4.5 g × 4.18 J/g°C × 90°C
Q1 = 1,678.5 J
Next, we need to determine the energy required for boiling the water at its boiling point to the steam phase at 100 degrees Celsius. This process is known as the heat of vaporization:
Q2 = heat of vaporization × mass
Q2 = 40.7 kJ/mol × (4.5 g / 18 g/mol)
Q2 = 40.7 kJ/mol × 0.25 mol
Q2 = 10.175 kJ
Finally, let's calculate the heat required to raise the temperature of the steam from 100 degrees Celsius to the desired temperature of 150 degrees Celsius:
Q3 = mass × specific heat capacity × temperature change
Q3 = 4.5 g × 2.03 J/g°C × (150°C - 100°C)
Q3 = 4.5 g × 2.03 J/g°C × 50°C
Q3 = 459.45 J
Now, sum up the three calculated heats to find the total heat required:
Total heat = Q1 + Q2 + Q3
Total heat = 1,678.5 J + 10,175 J + 459.45 J
Total heat = 12,312.95 J
Therefore, approximately 12,312.95 Joules of heat is needed to change 4.5 grams of water at 10 degrees Celsius into steam at 150 degrees Celsius.