# Iron (II) sulfate solution was added to 40 g of 8% sodium hydroxide alkali solution. The mass of the sediment formed?

Let’s compose the reaction equation: 2NaOH + FeSO4 = Na2SO4 + Fe (OH) 2.
1) Find the mass of the sodium hydroxide solute. To do this, we multiply the mass fraction of the solution by the mass of the solution and divide it by one hundred percent: 40 * 8/100 = 3.2 g.
2) Find the amount of sodium hydroxide substance. To do this, we divide its mass by molar mass: 3.2 / 40 = 0.08 mol.
3) According to the reaction equation, there are two moles of sodium hydroxide for one mole of iron hydroxide. This means that the amount of iron hydroxide substance is: 0.08 / 2 = 0.04 mol.
4) Sludge weight: 0.04 * 90 = 3.6 g – answer.

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