Question

Смесь магния и оксида магния массой 6,4 г обработали достаточным количеством разбавленной серной кислоты. При этом выделилось 2,24 л газа. Найти массовую долю магния в смеси.

Answer 1

Mg+H2SO4=MgSO4+H2
V(H2)=2,24л
n(H2)=2.24*22.4=0,1
n(Mg)=n(H2):1=0,1:1=0,1
m(Mg)= 0,1*24=2,4
Отсюда массовая доля равна:
2,4:6,4=37,5%

Answer 2

Calculation of Magnesium Mass Fraction in the Mixture

To find the mass fraction of magnesium in the mixture, we need to determine the amount of magnesium present in the mixture and divide it by the total mass of the mixture.

Given: - Mass of the magnesium-magnesium oxide mixture = 6.4 g - Volume of gas evolved during the reaction = 2.24 L

To calculate the mass fraction of magnesium, we can follow these steps:

1. Determine the molar volume of the gas evolved: - The molar volume of an ideal gas at standard temperature and pressure (STP) is 22.4 L/mol. - Since the given volume is 2.24 L, the number of moles of gas evolved can be calculated as: moles of gas evolved = volume of gas evolved / molar volume at STP.

2. Calculate the number of moles of magnesium consumed: - The balanced chemical equation for the reaction between magnesium and sulfuric acid is: Mg + H2SO4 → MgSO4 + H2 - From the balanced equation, we can see that 1 mole of magnesium reacts with 1 mole of hydrogen gas. - Therefore, the number of moles of magnesium consumed is equal to the number of moles of gas evolved.

3. Calculate the molar mass of magnesium: - The molar mass of magnesium (Mg) is approximately 24.31 g/mol.

4. Calculate the mass of magnesium in the mixture: - The mass of magnesium can be calculated by multiplying the number of moles of magnesium consumed by its molar mass: mass of magnesium = moles of magnesium * molar mass of magnesium.

5. Calculate the mass fraction of magnesium: - The mass fraction of magnesium is calculated by dividing the mass of magnesium by the total mass of the mixture: mass fraction of magnesium = mass of magnesium / mass of mixture.

Let's perform the calculations:

1. Calculate the moles of gas evolved: - moles of gas evolved = 2.24 L / 22.4 L/mol = 0.1 mol.

2. The number of moles of magnesium consumed is equal to the number of moles of gas evolved: - moles of magnesium = 0.1 mol.

3. The molar mass of magnesium is approximately 24.31 g/mol.

4. Calculate the mass of magnesium in the mixture: - mass of magnesium = moles of magnesium * molar mass of magnesium = 0.1 mol * 24.31 g/mol = 2.431 g.

5. Calculate the mass fraction of magnesium: - mass fraction of magnesium = mass of magnesium / mass of mixture = 2.431 g / 6.4 g ≈ 0.3797 ≈ 37.97%.

Therefore, the mass fraction of magnesium in the mixture is approximately 37.97%.

Please note that the given search results did not provide specific information about the mixture of magnesium and magnesium oxide, so the molar mass of magnesium and the balanced chemical equation were used as general knowledge.