What happens when you have a mixture of CO2 hydrate and methane hydrate when the temperature is 2.5 C and the pressure is 2 MPa. Does the methane come off and the CO2 hydrate remain
When you have a mixture of CO2 hydrate and methane hydrate, the behavior of the gas depends on the prevailing conditions of temperature and pressure. In the specific conditions you mentioned (temperature of 2.5°C and pressure of 2 MPa), it is likely that the methane will come off while the CO2 hydrate remains.
To understand why this happens, let's consider the concept of phase diagrams. A phase diagram represents the equilibrium between different phases of a substance (solid, liquid, and gas) as a function of temperature and pressure.
In the case of CO2 hydrate and methane hydrate mixtures, the phase diagram will show the conditions at which each hydrate phase (solid) can exist, as well as the conditions at which they can transition to the gas phase. Typically, for a given pressure, the hydrate phase with the higher formation temperature will be more stable.
In your specific scenario, with a temperature of 2.5°C and pressure of 2 MPa, it is likely that the CO2 hydrate will remain solid while the methane hydrate will start to transition to the gas phase. Methane hydrate has a lower formation temperature compared to CO2 hydrate, so under these conditions, the methane will tend to dissociate from the hydrate lattice, resulting in the release of methane gas.
Keep in mind that other factors, such as composition and impurities, can also influence the behavior of the hydrate mixture. The specific phase behavior can be determined by experimentally measuring the phase equilibria or by using complex mathematical models based on thermodynamic principles.