What is an experimental technique that could be used to determine the enthalpy of combustion of magnesium directly? Not using Hess's Law!!
any help is appreciated :)
Use a bomb calorimeter... or some kind of calorimeter... I'm just guessing; hopefully the calorimeter idea isn't stupid! Good luck.
thanks :)
No problem!
A 12.48g sample of an unknown metal, heated to 99'c was then plunged into 50mL of 25'c water. The temperature of the water rose to 28.1'c. The specific heat of water is 4.184J/g.
1. How many joules of energy did the water absorb?
2. How many joules of energy did the metal lose?
3. What is the heat capacity of the metal?
4. What is the specific heat of the metal?
One experimental technique that can be used to directly determine the enthalpy of combustion of magnesium is through calorimetry. Calorimetry is the measurement of heat flow during a chemical reaction.
To determine the enthalpy of combustion of magnesium directly, you can follow these steps:
1. Set up a simple calorimeter, which includes an insulated container (such as a foam cup) with a lid.
2. Measure the mass of the magnesium sample accurately using a balance.
3. Attach the magnesium sample to a fuse wire or a small metal rod.
4. Ignite the magnesium sample using a suitable ignition source, such as a Bunsen burner or a torch.
5. Place the burning magnesium sample inside the calorimeter and quickly close the lid to prevent heat from escaping.
6. Allow the reaction to complete and the calorimeter to reach thermal equilibrium, ensuring the heat is trapped inside.
7. Measure the temperature change (∆T) of the calorimeter using a thermometer, from the initial temperature to the maximum temperature reached.
8. Record the change in temperature and the mass of the magnesium sample burned.
To calculate the enthalpy of combustion (∆Hcomb) of magnesium, you can use the formula:
∆Hcomb = q / n
Where:
- ∆Hcomb is the enthalpy of combustion of magnesium
- q is the heat energy gained or lost by the calorimeter (q = mc∆T, where m is the mass of the calorimeter, c is the specific heat capacity of the calorimeter, and ∆T is the change in temperature)
- n is the number of moles of magnesium burned (n = m / M, where m is the mass of magnesium and M is the molar mass of magnesium)
By analyzing the temperature change and applying the above formula, you can determine the enthalpy of combustion of magnesium directly, without using Hess's Law.