Oilers/Plant Tenders (HHC) Civil Service Practice Exam

Which of the following lubricants is usually not attacked by acids?

1. Graphite

2. Vegetable oil

3. Mineral oil

4. Synthetic oil

The correct answer is: Graphite

Graphite is a solid lubricant that is well-known for its ability to withstand high temperatures and chemical corrosion, including resistance to acids. This makes it an ideal choice in applications where exposure to acidic environments might occur. Unlike liquid lubricants, which can often be compromised or degraded by acidic substances, graphite maintains its structural integrity and lubricating properties due to its unique layered crystalline structure. Vegetable oils and mineral oils, on the other hand, can be susceptible to acid degradation, which impacts their effectiveness as lubricants. Synthetic oils, while more resistant than their natural counterparts, can also face some level of attack by strong acids, depending on their specific chemical formulation. Thus, graphite stands out as the most resistant lubricant to acid attack in this context.