Final answer:
Tungsten is commonly used as the anode in x-ray tubes due to it having a high melting point, allowing it to absorb significant energy without melting. For electrochemical cells, an anode is where oxidation occurs and a cathode is where reduction occurs; tungsten could be used for either electrode based on the specific reactions.
Step-by-step explanation:
When considering whether tungsten serves as an anode or cathode, it is important to understand the context in which the material is used. If we are discussing x-ray tubes, tungsten is commonly used as the anode material. In x-ray tubes, tungsten's high melting point is crucial because it must be able to absorb a significant amount of energy from the impinging electrons without melting. This capability is vital to withstand the large photon energies typical of characteristic x-rays from heavy elements. The necessity of a high-melting-point material is due to electrons accelerating to such a degree that at least 72.5 kV is needed to create inner-shell vacancies, resulting in x-ray emission.
In electrochemical cells, the anode is generally the electrode where oxidation occurs, meaning electrons are released by the substance on the anode, and this is considered the negative electrode in the circuit. Conversely, the cathode is where reduction happens, where electrons are gained by the substances on the cathode, making it the positive electrode in the circuit. Tungsten could potentially serve as either an anode or a cathode in different electrochemical setups, depending on the specific reactions involved.