im working on a lab in chemistry called measuring energy changes :Calorimetry
how to you determine the molar latent heat of fusion of ice using q=mcT ??
why was the ice driedbefore it was placed in water?
why is hot warer ysed rather than room temp?
in which dirextion would your value for molar latent heat of fusion of ice have shifted if these step[s has not been carried out?
help would be greatly appreciated !
If the ice had not been dry, you would have been measuring the two things: heat to melt ice, and heat to heat up the surface melted water, making the calculations more complex
Hot water is used to get a large change in temperature of the water, and to drive the final temperature close to room temperature (so measuring heat transfer is easier).
To determine the molar latent heat of fusion of ice using the equation q=mcΔT, you will need to measure the heat absorbed or released by the ice as it melts.
Here are the steps to follow:
1. Start by drying the ice before placing it in water. This is done to ensure that any excess water on the surface of the ice is removed. This step is important because having excess water on the surface could lead to inaccurate measurements and affect the heat transfer.
2. Next, weigh the dry ice and record its mass (m). You will need this value for the calculations.
3. Prepare a known volume (V) of hot water. The specific temperature of the hot water is used rather than room temperature to increase the rate of heat transfer and allow for faster melting of the ice.
4. Place the ice in a calorimeter container filled with the hot water. Allow the ice to melt completely. The heat released by the hot water, which causes the ice to melt, is absorbed by the ice itself.
5. Measure the final temperature (T) of the water after the ice has melted completely. Ensure to stir the mixture thoroughly during this time to ensure uniform temperature distribution.
6. Calculate the heat absorbed or released by the ice using the equation q = mcΔT, where q is the heat, m is the mass of the ice, c is the specific heat capacity of water (4.184 J/g°C), and ΔT is the change in temperature of the water.
7. Since the heat released by the hot water is equal to the heat absorbed by the ice (as per the Law of Conservation of Energy), you can then calculate the molar latent heat of fusion of ice using the equation q = nΔH_f, where n is the number of moles of ice and ΔH_f is the molar latent heat of fusion. Rearranging the equation, you get ΔH_f = q/n.
Regarding the last question, if the ice was not dried properly or excess water was present, it would increase the mass of the ice used in the calculation. Therefore, the value for the molar latent heat of fusion of ice would be higher than the actual value. On the other hand, if room temperature water was used instead of hot water, the rate of heat transfer would be slower, leading to a lower value for the molar latent heat of fusion of ice. Correctly drying the ice and using hot water help obtain more accurate results.
I hope this explanation helps you with your lab!