I have to calculate the ΔV= final volume-initial volume
For the first trial the final volume was .005mL the initial volume was .03mL, which equaled to
-.025mL. The volume was negative because it was exothermic reaction. For the second trial the final volume was 0.015 and the initial volume was 0.03, which equaled to -.015mL.
Now I have to convert ΔV to ΔH273 values. TheΔH273 is the molar enthalpy change for the reaction of the magnesium metal. How do I compute the mean value of ΔH273?
ΔH=ΔE +nRT
Also calculate the ΔE273 from the mean value of ΔH273?
The equation for the reaction that took place was: Mg(s) +2H+(aq)→Mg+2(aq) +H2 (aq)
To compute the mean value of ΔH273, you need to take the average of the ΔH273 values obtained from the two trials. Follow these steps:
1. Convert the ΔV values from mL to L by dividing each value by 1000:
- For the first trial: ΔV = -0.025 mL = -0.025/1000 L = -2.5x10^-5 L
- For the second trial: ΔV = -0.015 mL = -0.015/1000 L = -1.5x10^-5 L
2. Use the equation ΔH = ΔE + nRT to find ΔH273.
- ΔE is the change in internal energy of the system.
- n is the stoichiometric coefficient of the species undergoing the reaction (in this case, 1).
- R is the ideal gas constant (8.314 J/(mol·K)).
- T is the temperature in Kelvin (273 K).
For each trial, you can calculate ΔE273 using the given ΔV value and the known values:
- For the first trial: ΔH273 = ΔE273 + nRT ⇒ ΔE273 = ΔH273 - nRT = -2.5x10^-5 + (1)(8.314)(273)
- For the second trial: ΔH273 = ΔE273 + nRT ⇒ ΔE273 = ΔH273 - nRT = -1.5x10^-5 + (1)(8.314)(273)
3. Calculate the mean value of ΔH273 by taking the average of the ΔH273 values obtained from the two trials.
4. Calculate the ΔE273 from the mean value of ΔH273 by substituting it into the equation: ΔH273 = ΔE273 + nRT.
Note: Make sure to use the appropriate units (Joules for ΔH and ΔE, Kelvin for temperature, and moles for n).
To compute the mean value of ΔH273, you need to first calculate the ΔE273 using the equation ΔH = ΔE + nRT.
1. Determine the moles of Mg reacted:
- From the balanced equation, you can see that for every one mole of Mg reacted, the enthalpy change is ΔH273.
- Calculate the moles of Mg reacted by dividing the change in volume (ΔV) by the molar volume, which is the initial volume of the Mg (0.03 mL) multiplied by its molar density.
2. Calculate the ΔE273:
- Since ΔH = ΔE + nRT, rearrange the equation to solve for ΔE:
ΔE = ΔH - nRT
- Plug in the values of ΔH273 from step 1, the known values for R (the ideal gas constant), T (temperature in Kelvin), and n (the number of moles of Mg from step 1).
- Calculate the value of ΔE273.
3. Repeat steps 1 and 2 for both trials and calculate the mean value of ΔE273.
Please provide the temperature at which the reactions took place so that I can assist you further in calculating ΔE273 and the mean value of ΔE273.