Sulfuric acid is very poisonous because of its acidity and corrosiveness. When it is mixed with sugar, it turns it into carbon. When it is dissolved in water, it becomes less harmful (does not make things black) but is still corrosive like normal acids. It reacts with metals to produce hydrogen and the metal sulfate. Some metals, such as tin, make sulfur dioxide and tin(II) sulfate. It reacts with sodium chloride to make hydrogen chloride.