# Mixed 94 g of 15% copper nitrate solution and 80 g of 5% sodium hydroxide solution. Find the mass of sediment formed.

to solve this problem, you first need to write the equation of the chemical reaction: Cu (NO3) 2 + 2NaOH => Cu (OH) 2 ↓ + 2NaNO3
Then you need to find the mass and amount of the copper nitrate substance:
m (Cu (NO3) 2) = 94 / 0.15 = 14.1 g.
n (Cu (NO3) 2) = 14.1 / 188 = 0.075 mol.
Likewise with sodium hydroxide:
m (NaOH) = 80 * 0.05 = 4 g.
n (NaOH) = 4/40 = 0.1 mol.
The reaction shows that there is a lack of NaOH (for 1 mol of NaOH, according to the equation, 0.1 / 2 = 0.05 mol), therefore, we count by n (NaOH) = 4/40 = 0.1 mol.
n (Cu (OH) 2) = 1/2 * n (NaOH) = 0.05 mol.
We find the mass of the sediment: m (Cu (OH) 2) = 0.05 * 98 = 4.9 g.

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