I was thinking of an interesting landmark to put on my conworld, and I went with the "large body of acid" trope. This lake would be about the size of Lake Superior, and near the equator. The atmosphere is very similar to Earth's, but with about 5% Argon comprising it. The underlying rock has high concentrations of minerals like quartz and graphite, with some other minerals like lazulite and diamond. It is a very dense rock and is good at insulating against radiation. What colour would this acid lake be?
Given the chemical composition of the underlying rock, I'd suspect that the lake will actually be a kind of ordinary darkish brown.
The pretty blue of Earth's acid lakes is due to iron sulphate in the solution. The pretty blue of sulphur lakes is due to the flame's colour.
On this other world, the underlying rock is defined by high concentrations of quartz and graphite, with some other minerals like lazulite and diamond.
Sulphuric acid itself, like water, is clear, and will take on the apparent colour of whatever is behind it:
Sulfuric Acid Lakes, like Thorne said, are presented as Turquoise.
Very Very Sulfuric Lands can be an Orange-Yellow, or Green, depending on the concentration of sulfur.
But one very important feature... Multan Sulfur, usually around Sulfur Lakes, will Light on Fire at night, producing a beautiful but deadly blue fire or blue lava
I loved the idea of adding this in, and had to mention the blue lava. its an amazing sight