Question

Медный стержень массой 140,8г выдержали в растворе нитрата серебра(1),после чего его масса составила 171,2г. Какой объём раствора с w(HNO3)=0.32 (р=1.2) нужен для растворения стержня после реакции?

Answer 1

Calculation of the Volume of Nitric Acid Solution Needed

To calculate the volume of nitric acid solution needed to dissolve the copper rod, we can use the information provided about the mass of the rod before and after the reaction.

Given: - Mass of the copper rod before reaction = 140.8 g - Mass of the copper rod after reaction = 171.2 g - Concentration of nitric acid solution (HNO3) = 0.32 M - Density of the nitric acid solution = 1.2 g/mL

To find the volume of the nitric acid solution needed, we can follow these steps:

1. Calculate the change in mass of the copper rod: - Change in mass = Mass after reaction - Mass before reaction - Change in mass = 171.2 g - 140.8 g - Change in mass = 30.4 g

2. Convert the change in mass to moles of copper: - Moles of copper = Change in mass / molar mass of copper - The molar mass of copper (Cu) is approximately 63.55 g/mol. - Moles of copper = 30.4 g / 63.55 g/mol - Moles of copper ≈ 0.4789 mol

3. Use the balanced chemical equation for the reaction between copper and nitric acid to determine the stoichiometry: - The balanced equation is: 3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O - From the equation, we can see that 3 moles of copper react with 8 moles of nitric acid.

4. Calculate the moles of nitric acid needed: - Moles of nitric acid = (moles of copper) × (moles of nitric acid / moles of copper) - Moles of nitric acid = 0.4789 mol × (8 mol HNO3 / 3 mol Cu) - Moles of nitric acid ≈ 1.277 mol

5. Calculate the volume of the nitric acid solution needed: - Volume of nitric acid solution = (moles of nitric acid) / (concentration of nitric acid solution) - Volume of nitric acid solution = 1.277 mol / 0.32 M - Volume of nitric acid solution ≈ 3.9906 L

Therefore, approximately 3.9906 liters of the nitric acid solution with a concentration of 0.32 M are needed to dissolve the copper rod after the reaction.