Cu(s) + 4HNO3(aq) ---> Cu(NO3)2(aq) + 2H2O(l) + 2NO2(g)

Solid copper is reacting with nitric acid, becoming a blue solution of aqueous cupric nitrate and H2O, and a brown, poisonous gas: nitrogen oxide.

Natalie is striving for accuracy by getting down to eye level with the meniscus, and measuring the the exact amount of nitric acid.