How can the charges on the surface of a liquid in a container be made harmless?

The presence of charges on the surface of a liquid can lead to issues such as static electricity, which can be hazardous in certain environments or applications. Purging the container helps in making these charges harmless by removing the liquid from the container, thereby eliminating the charged surface and potentially preventing any discharge or spark that could pose a safety risk. This method effectively resets the conditions of the liquid and its surroundings, ensuring that any accumulated charges are not present when the container is refilled or reused.

While other methods, such as mixing the liquid or increasing humidity, could theoretically impact surface charges, they do not specifically target the removal of those charges as effectively as purging. Mixing the liquid might redistribute charges but doesn't eliminate them, and increased humidity can reduce static buildup but relies on environmental conditions rather than directly addressing the charges on the surface themselves. Cooling the liquid may alter its properties but does not inherently neutralize the surface charges.