1. Graph of the changes from ice to steam:
To create the graph, we need to represent the different stages of the phase change from ice to steam.
- First, plot a point at -20°C to represent the initial temperature of the ice.
- Then, draw a straight line with a positive slope to depict the heat absorption during the heating process from -20°C to 0°C. The slope represents the specific heat capacity of ice (2.06 J g^(-1) K^(-1)).
- At 0°C, draw a horizontal line to represent the phase change from ice to water. This line represents the heat of fusion, which is 334.16 J g^(-1). The temperature stays constant at 0°C during this phase change.
- After that, draw another straight line with a positive slope from 0°C to 100°C to represent the heating process from water to steam. The slope of this line represents the specific heat capacity of liquid water (4.184 J g^(-1) K^(-1)).
- At 100°C, draw another horizontal line to represent the phase change from water to steam. This line represents the heat of vaporization, which is 2259 J g^(-1). The temperature remains constant at 100°C during this phase change.
- Finally, draw a straight line with a positive slope from 100°C to 135°C to represent the heating process from steam at 100°C to steam at 135°C. The slope of this line represents the specific heat capacity of steam (2.02 J g^(-1) K^(-1)).
ii. Calculation of the energy needed to change the ice to steam:
To calculate the energy needed, we need to consider the different stages of the phase change and apply the relevant formulas.
- First, calculate the energy required to heat the ice from -20°C to 0°C using the formula:
Energy = mass × specific heat capacity × temperature change
Energy = 50 g × 2.06 J g^(-1) K^(-1) × (0°C - (-20°C))
- Next, calculate the energy required for the phase change from ice to water using the formula:
Energy = mass × heat of fusion
Energy = 50 g × 334.16 J g^(-1)
- Then, calculate the energy required to heat the water from 0°C to 100°C using the formula:
Energy = mass × specific heat capacity × temperature change
Energy = 50 g × 4.184 J g^(-1) K^(-1) × (100°C - 0°C)
- After that, calculate the energy required for the phase change from water to steam using the formula:
Energy = mass × heat of vaporization
Energy = 50 g × 2259 J g^(-1)
- Finally, calculate the energy required to heat the steam from 100°C to 135°C using the formula:
Energy = mass × specific heat capacity × temperature change
Energy = 50 g × 2.02 J g^(-1) K^(-1) × (135°C - 100°C)
To find the total energy needed, sum up all the individual energy values calculated above.