Since 1891 lighting lamps have been manufactured in the Netherlands. The improvement today in comparison to the first lamp is enormous , especially with the intorduction of the gas discharge lamps. The life- time has increased by orders of magnitude . the colour is also an important aspect. Rare earth metal compunds like `CeBr_(3)` are now included to reach a colour temperature of 6000K in the lamp the compounds are ionic solids at room temperature , and upon heating they sublime partially to give a vapour of neutral metal halide molecules . To achieve a high vapour pressure, the sublimation enthalpy should be as low as possible.
Conclusion in relation to the previous answers. was adding CsBr a good idea ? Mark the correct answer.
`implies` Adding CsBr is counterproductive.
`implies` Adding CsBr has no influence
`implies` Adding CsBr is advantageous
`implies` From these data no clear answer can be given.

Answer

To determine whether adding CsBr is a good idea for achieving a high vapor pressure in gas discharge lamps, we need to analyze the implications of adding CsBr in relation to sublimation enthalpy and vapor pressure.

### Step-by-Step Solution:

1. **Understanding the Role of Sublimation Enthalpy**:
- Sublimation enthalpy is the energy required to convert a solid into a gas at a given temperature. Lower sublimation enthalpy generally leads to higher vapor pressure because less energy is needed for the solid to transition into the gas phase.

**Hint**: Recall that lower energy requirements for sublimation favor higher vapor pressures.

2. **Analyzing CsBr**:
- CsBr (cesium bromide) is an ionic compound. The introduction of CsBr into the lamp may affect the sublimation enthalpy of the overall mixture of compounds used in the lamp.

**Hint**: Consider how the ionic nature of CsBr might influence the sublimation properties of the mixture.

3. **Comparing Sublimation Enthalpies**:
- If CsBr has a higher sublimation enthalpy compared to other compounds in the lamp, adding it could potentially increase the overall sublimation enthalpy of the mixture, leading to a lower vapor pressure.

**Hint**: Think about how different ionic compounds compare in terms of their sublimation enthalpies.

4. **Evaluating the Options**:
- Based on the above analysis, we can evaluate the options:
- **Adding CsBr is counterproductive**: This could be true if CsBr increases sublimation enthalpy.
- **Adding CsBr has no influence**: This seems unlikely if CsBr significantly alters the sublimation properties.
- **Adding CsBr is advantageous**: This would only be true if it lowers the sublimation enthalpy.
- **From these data, no clear answer can be given**: This could be true if we lack specific data on sublimation enthalpies.

5. **Conclusion**:
- Given that we are aiming for a high vapor pressure and that adding CsBr could potentially increase the sublimation enthalpy, the most reasonable conclusion is that **adding CsBr is counterproductive**.

### Final Answer:
- **Adding CsBr is counterproductive.**