Question
12 g of magnesium ribbon was heated in a crucible. At the end of the reaction 20 g of magnesiu m oxide had been produced. What mass of oxygen had reacted with the magnesium? Enter a number g
Answer
3.6
(206 Votes)
Barclay
Elite · Tutor for 8 years
Answer
20 - 12 = 8 g
Explanation
In this problem, we are given the starting mass of magnesium ribbon which reacted and the final mass of magnesium oxide formed, where magnesium oxide is a compound composed of magnesium and oxygen. We are asked to find the mass of oxygen that reacted with the magnesium to form the given amount of magnesium oxide. By utilizing the concept of conservation of mass which derives from the law of conservation of matter that postulates that matter cannot be created or destroyed, we can assert that the starting magnesium + oxygen combined mass must equal the final mass of magnesium oxide. Directly, we will subtract the initial mass of magnesium from the final mass of magnesium oxide to identify the mass of oxygen.