Cu(s) + 4HNO₃(aq) → Cu(NO₃)₂(aq) + 2NO₂(g) + 2H₂O(1)
Each student in a class placed a 2.00-gram 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 copper in the mixture and HNO₃ is depicted above.
The students observed that a brown gas was released from the beakers and that solutions turned blue, indicating the formation of Cu²⁺. The solutions were then diluted with distilled water to known volumes. The students determined that the reaction produced 0.010 moles of Cu(NO3)₂. Based on the measurement, what was the percent of Cu by mass in the original 2.00-gram sample of the mixture?
A) 16%
B) 32%
C) 64%
D) 96%