4 Copper hydroxide, copper oxide and copper sulfide are three compounds of copper - Edexcel - GCSE Chemistry - Question 4 - 2017 - Paper 1

The state symbol for copper hydroxide as a precipitate is (s). Therefore, the correct choice is:

D (s)

To find the relative formula mass of copper hydroxide, calculate:

• Copper (Cu): 63.5
• Oxygen (O): 16 × 2 = 32
• Hydrogen (H): 1 × 2 = 2

So, total relative mass = 63.5 + 32 + 2 = 97.5.

Thus, the correct answer is:

C 97.5

First, calculate the number of moles for each element:

• Moles of Copper (Cu): $ext{Moles} = \frac{\text{mass}}{\text{molar mass}} = \frac{12.7}{63.5} \approx 0.200 \text{ moles}$

• Moles of Sulfur (S): $\text{Moles} = \frac{3.2}{32} = 0.100 \text{ moles}$

Now, find the ratio:

• The ratio of Cu to S = 0.200 : 0.100 = 2 : 1

Thus, the empirical formula is:

$\text{Cu}_2\text{S}$

First, calculate the relative formula mass of copper oxide (CuO):

• Copper (Cu): 63.5
• Oxygen (O): 16

Total = 63.5 + 16 = 79.5 g/mol.

Next, calculate the maximum mass of CuO produced from 25.4 g of Cu:

1. Calculate moles of Cu: $\text{Moles of Cu} = \frac{25.4}{63.5} \approx 0.400 \text{ moles}$
2. The reaction shows a 1:1 ratio of Cu to CuO, so moles of CuO produced = 0.400 moles.
3. Finally, calculate the mass: $\text{Mass of CuO} = \text{moles} \times \text{molar mass} = 0.400 \times 79.5 = 31.8 ext{ g}$

Thus, the maximum mass of copper oxide produced is:

31.8 g