It’s the hydration reaction that generates all that heat: Mixing 100 ml of concentrated sulfuric acid and 100 ml of water at 19 ☌ reaches a temperature over 131 ☌ (well past the boiling point of water) in under a minute. A lot of heat gets generated, even when sulfuric acid and water are mixed properly. The acid is much heavier than water, so water added to it reacts with the top layer first.
#Diluting gravity lab answers skin
Sulfuric acid quickly dehydrates proteins and carbohydrates in skin and muscle. Partly, this is because it reacts so violently with skin and clothing.
Sulfuric acid (H 2SO 4) is the most dangerous common acid to dilute. On the other hand, if you pour acid on top of or into water, the water rises over the acid before mixing and contains the reaction. In this situation, the liquid readily boils and spits. So, if you put water on top of acid, the heat that’s generated is at the acid surface. Also, some strong acids have a higher specific gravity or density than water. Diluting acid with water is exothermic, so it’s easier to boil and splash water added to acid than acid added to water because water has a high heat capacity and can absorb a lot of heat. There are a few factors that make it better to add acid to water. Here, all the acid reacts, but there is extra water to absorb the heat, lessening the chance of boiling. If you add a little concentrated acid to a lot of water, water is the limiting reactant and the resulting solution is more dilute.
The solution violently boils, spitting concentrated acid out of its container. The hydration reaction uses all the water (acid is the limiting reactant), generating a lot of heat. If you add a little water to a lot of concentrated acid, the resulting solution is still concentrated. Always add acid to water and not the other way around. When you mix strong acids and water, it makes a difference whether you add acid to water or water to acid. Otherwise, the acid can splatter and splash up. This entry was posted on by Anne Helmenstine (updated on May 2, 2021)Īlways add acid to water, not water to acid.
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