what happens to the mass of copper when over heated and forms copper(ii) oxide
If you have pure Cu and you add oxygen to it, the Cu forms CuO and the Cu gains weight (mass) because of the added oxygen.
When copper is heated and reacts with oxygen to form copper(II) oxide, there is a chemical change taking place. Let's break it down step by step:
1. Start by writing the balanced chemical equation for the reaction:
2Cu + O2 → 2CuO
2. According to stoichiometry, the balanced equation tells us the ratio in which the reactants combine. In this case, it is 2 moles of copper reacting with 1 mole of oxygen to produce 2 moles of copper(II) oxide.
3. To determine the mass change of copper, you need to consider the law of conservation of mass, which states that mass cannot be created or destroyed in a chemical reaction. Therefore, the total mass of the copper and oxygen atoms before the reaction must equal the total mass of copper(II) oxide after the reaction.
4. To calculate the mass change, you need the molar mass of copper (Cu) and copper(II) oxide (CuO). The atomic mass of copper is approximately 63.55 g/mol, while the molecular mass of copper(II) oxide is approximately 79.55 g/mol.
5. Let's assume we have 10 grams of copper reacting. To convert grams to moles, you divide by the molar mass of copper (63.55 g/mol). This gives us approximately 0.157 moles of copper.
6. Since the reactants have a 2:1 ratio, we need half the number of moles of oxygen (O2), which is 0.157/2 = 0.079 moles.
7. To find the mass of copper(II) oxide formed, we multiply the molar mass of CuO (79.55 g/mol) by the number of moles of copper(II) oxide produced, which is 0.079 moles. This gives us approximately 6.28 grams of copper(II) oxide.
8. Now, to calculate the mass change, we subtract the mass of copper(II) oxide formed (6.28 g) from the mass of copper initially present (10 g):
Mass change = Initial mass - Final mass
Mass change = 10 g - 6.28 g
Mass change ≈ 3.72 grams
So, when copper is heated and forms copper(II) oxide, the mass of copper decreases by about 3.72 grams. This mass decrease corresponds to the oxygen atoms that combine with copper to form copper(II) oxide.