Question

определить массовые доли Al и Mg в их сплаве с Cu ,если известно ,что в результате действия на сплав массой -2,6 грамм раствором щелочи выделилось 1,12 литров H2 н.у. а при действии на такую же массу сплава HCl выделилось 2,24 литра H2 н.у.

Answer 1

При действие такого сплава АI Mg Cu раствором щелочи только  AI идет в реакции 
    Хг                                     1,12л
2АI  +6NaOH  = 2Na3AIO3 + 3H2                Х= 54*1,12/67,2= 0,9г АI в состав сплава
54г                                        67,2л
0.9г                           Хл
2АI + 6НСI = 2AICI3 +3H2                         Х= 1,12л
 54г                            67,2л 
Xг                       1,12л
Мg+2HCI =MgCI2 +H2               Х= 24*1,12/22,4=1,2г Мg в состав сплава  
24г                        22,4л

2,6г -----------------100%
0,9г(АI)--------------Х%      Х= 34,6%
2,6------------------100%
1,2г(Мg)-----------Х%          Х=46,15%

Answer 2

Determining the Mass Fractions of Al and Mg in the Cu Alloy

To determine the mass fractions of Al and Mg in the Cu alloy, we can use the information provided about the reaction of the alloy with different solutions.

According to the given information, when a solution of alkali (NaOH) was added to the alloy, 1.12 liters of H2 gas at standard temperature and pressure (n.t.p.) were released. Additionally, when a solution of hydrochloric acid (HCl) was added to the same mass of the alloy, 2.24 liters of H2 gas at n.t.p. were released.

To calculate the mass fractions of Al and Mg in the alloy, we need to use the stoichiometry of the reactions involved.

Let's assume the mass of the alloy is 2.6 grams.

Reaction with NaOH Solution

The reaction between the alloy and NaOH can be represented as follows: 2Al + 6NaOH + 2H2O -> 2Na3AlO3 + 3H2

From the reaction equation, we can see that 2 moles of Al react with 6 moles of NaOH to produce 3 moles of H2 gas.

Using the ideal gas law, we can convert the volume of H2 gas to moles: 1.12 liters of H2 gas at n.t.p. is approximately 0.05 moles of H2 gas.

Since 2 moles of Al produce 3 moles of H2 gas, we can calculate the moles of Al in the alloy: (0.05 moles H2) * (2 moles Al / 3 moles H2) = 0.033 moles Al

To calculate the mass of Al in the alloy, we need to know the molar mass of Al. The molar mass of Al is approximately 26.98 g/mol.

The mass of Al in the alloy is: (0.033 moles Al) * (26.98 g/mol) = 0.89 grams Al

Reaction with HCl Solution

The reaction between the alloy and HCl can be represented as follows: Mg + 2HCl -> MgCl2 + H2

From the reaction equation, we can see that 1 mole of Mg reacts with 2 moles of HCl to produce 1 mole of H2 gas.

Using the ideal gas law, we can convert the volume of H2 gas to moles: 2.24 liters of H2 gas at n.t.p. is approximately 0.1 moles of H2 gas.

Since 1 mole of Mg produces 1 mole of H2 gas, we can calculate the moles of Mg in the alloy: 0.1 moles H2 = 0.1 moles Mg

To calculate the mass of Mg in the alloy, we need to know the molar mass of Mg. The molar mass of Mg is approximately 24.31 g/mol.

The mass of Mg in the alloy is: 0.1 moles Mg * 24.31 g/mol = 2.43 grams Mg

Mass Fractions of Al and Mg

To calculate the mass fractions of Al and Mg in the alloy, we can use the following formulas:

Mass fraction of Al = (mass of Al / total mass of alloy) * 100% Mass fraction of Mg = (mass of Mg / total mass of alloy) * 100%

Using the values we calculated earlier: Mass fraction of Al = (0.89 grams Al / 2.6 grams alloy) * 100% ≈ 34.2% Mass fraction of Mg = (2.43 grams Mg / 2.6 grams alloy) * 100% ≈ 93.5%

Therefore, the mass fractions of Al and Mg in the Cu alloy are approximately 34.2% and 93.5%, respectively.

Please note that the calculated mass fractions are approximate values and may vary depending on the accuracy of the given information and the assumptions made during the calculations.