Calculate the amount of heat in kilojoules reased when 50 of steam at 125 C are converted to 50 grams of ice at -125 C.
AHsteam = m * Cp steam * At
q1= 50g * 4.184 J/g C * (125-100)C= 5.23 x 10^J
q2= m * AH
50g * 5230 J/g = 2.61 x 10^5 J
q3= 50g *4.184 J/g C * (100-0)C= 2.10 x10^4 J
q4= 50g * 20920 J/g = 1.04 x 10^6 J
q5 = 50g * 4.184 J/g C * (0-125)= -2.61 x 10^4 J
AH total = 1 + 2 + 3 + 4 + 5 = 1.30 x 10^6 J endothermic
please let me know if it correct
It is not correct. You did not use the correct specific heats for steam, nor for ice. In addition, you did not use the correct values for Latent heats of fusion or vaporization.
Your calculations appear to be mostly correct, but there is a small mistake in how you calculated q2. Let me go through the calculations step by step to help you understand the process.
q1: This calculation is correct. It represents the amount of heat required to heat up 50 grams of steam from 100°C to 125°C (assuming the starting temperature is 100°C, as you did not specify).
q1 = 50g * 4.184 J/g°C * (125°C - 100°C) = 5.23 x 10^3 J
q2: Here is where the mistake occurred. To find the heat required for the phase change from steam to water (latent heat), you need to multiply the mass of the steam by the enthalpy of vaporization (AHvap). The specific heat capacity (Cp) should not be used in this calculation.
q2 = 50g * AHvap
Since you did not provide the enthalpy of vaporization, I cannot calculate the exact value for q2. However, assuming a typical value of around 2.26 x 10^6 J/kg (or 2.26 x 10^4 J/g), the calculation would be:
q2 = 50g * 2.26 x 10^4 J/g = 1.13 x 10^6 J
q3: This calculation is correct. It represents the amount of heat required to cool down 50 grams of water from 100°C to 0°C.
q3 = 50g * 4.184 J/g°C * (100°C - 0°C) = 2.10 x 10^4 J
q4: This calculation is correct. It represents the amount of heat required for the phase change from water to ice.
q4 = 50g * AHfusion
Again, I cannot calculate the exact value without knowing the enthalpy of fusion (AHfusion), but assuming a typical value of around 3.34 x 10^5 J/kg (or 3.34 x 10^3 J/g), the calculation would be:
q4 = 50g * 3.34 x 10^3 J/g = 1.67 x 10^5 J
q5: This calculation is correct. It represents the amount of heat required to cool down 50 grams of ice from 0°C to -125°C.
q5 = 50g * 2.09 J/g°C * (0°C - (-125°C)) = -2.61 x 10^4 J
To find the total heat change (AHtotal), you need to sum up all the individual heat changes:
AHtotal = q1 + q2 + q3 + q4 + q5
Since I don't have the exact values for q2 and q4, I cannot calculate the final answer. However, you can substitute the correct values into the equation above and obtain the accurate result.