Questions 10-13 refer to the following information. Cu(s) + 4 HNO3(aq) → Cu(NO3)2(aq) + 2 NO2(g) + 2 — Stoichiometry Chemistry Question

Questions 10-13 refer to the following information.

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

Each student in a class placed a 2.00 g sample of a mixture of Cu and Al in a beaker and placed the beaker in a fume hood. The students slowly poured 15.0 mL of 15.8 M HNO₃(aq) into their beakers. The reaction between the copper in the mixture and the HNO₃(aq) is represented by the equation above. The students observed that a brown gas was released from beakers and that the solutions turned blue, indicating the formation of Cu²⁺(aq). The solutions were then diluted with distilled water to known volumes.

1. The students determined that the reaction produced 0.010 mol of Cu(NO₃)₂. Based on the measurement, what was the percent of Cu by mass in the original 2.00 g sample of the mixture?