What mass of copper (II) hydroxide decomposed when heated if 72 g of water was released?

Let’s write the equation:
1. Cu (OH) 2 = CuO + H2O – decomposition occurs when heated, copper oxide and water are released;
2. Let’s make calculations using the formulas:
M Cu (OH) 2 = 97.5 g / mol;
M (H2O) = 18 g / mol;
3. Let’s calculate the number of moles of water and copper hydroxide:
Y (H2O) = m / M = 72/18 = 4 mol;
X mol (Cu (OH) 2 – 4 mol (CuO);
-1 mol -1 mol hence, X mol Cu (OH) 2 = 1 * 4/1 = 4 mol;
4. Find the mass of the original substance:
mCu (OH) 2 = Y * M = 4 * 97.5 = 390 g.
Answer: the reaction will require copper hydroxide weighing 390 g.



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