My teacher provided info about a worksheet of problems.
Special Heat of water: 4.184
Special Heat of Steam: 2.09
Special Heat of Ice: 1.8
Based on this info, and the notes we have taken on phase changes, we are supposed to find out how much energy is needed to change certain substances.
I thought, however, that in order to create a phase change, one must use the q=m,delta,Hfusion or m,delta,Hvap. How can I perform these equations without the Hvap/fusion info provided?!
Question 4, for example asks...
...60g of water at 43 degrees celcius to steam at 140 degrees celcius.
Help please?!?!?
To solve the problem without the specific heat of vaporization (Hvap) or fusion (Hfusion), you can follow these steps:
1. Determine the mass of water that needs to undergo a phase change. In this case, it is given that you have 60 grams of water.
2. To heat the water from 43 degrees Celsius to its boiling point, you need to calculate the energy required using the formula q = m * C * ΔT, where q is the energy, m is the mass of the substance, C is the specific heat, and ΔT is the change in temperature. Given that the specific heat of water is 4.184 J/g°C, and the change in temperature is (100 - 43) = 57°C, you can calculate:
q = 60 g * 4.184 J/g°C * 57°C = 14212.56 J
So, to heat the water from 43°C to its boiling point, you need 14212.56 Joules of energy.
3. To convert the water at its boiling point (100°C) to steam at 140°C, you need to use the latent heat of vaporization. However, since the specific heat of vaporization (Hvap) value is not given, you can estimate the energy required using the specific heat of steam. Given that the specific heat of steam is 2.09 J/g°C, and the change in temperature is (140 - 100) = 40°C, you can calculate:
q = 60 g * 2.09 J/g°C * 40°C = 4984.8 J
So, to convert the water at its boiling point to steam at 140°C, you need 4984.8 Joules of energy.
4. Add the two energy values together to find the total energy required:
Total energy = 14212.56 J + 4984.8 J = 19197.36 J
Therefore, to change 60 grams of water at 43°C to steam at 140°C, you need approximately 19197.36 Joules of energy.