Question

Помогите, пожалуйста, решить химию! Нужны полные решения. С1. 10 г бария растворили в избытке воды. Вычислите объём газа(л), выделившегося в результате реакции при н.у. С2. 105 г фосфата калия растворили в 500 г воды. Вычислите массовую долю (%) соли в полученном растворе

Answer 1

1) Напишем уравнение реакции:
Ba + 2 H2O (изб.) = Ba(OH)2 + H2
Количество вещества: n (Ba) = m/M = 10г / 137 г/моль = 0,073 моль
По уравнению реакции n (H2) = n(Ba) = 0,073 моль
V (H2) = n * Vm = 0,073 моль х 22,4л/моль = 1,635 моль 

2) Масса раствора: m = 105 г + 500 г = 605 г 
Массовая доля фосфата калия: w = m (ф) / m = 105/605 * 100%  = 17,355%  

Answer 2

Solution for C1:

To calculate the volume of gas produced when 10 g of barium is dissolved in excess water, we need to determine the balanced chemical equation for the reaction. Barium reacts with water to form barium hydroxide and hydrogen gas.

The balanced chemical equation for this reaction is:

Ba + 2H2O → Ba(OH)2 + H2

According to the stoichiometry of the reaction, 1 mole of barium reacts with 2 moles of water to produce 1 mole of hydrogen gas. We can use this information to calculate the number of moles of hydrogen gas produced.

First, we need to calculate the number of moles of barium. The molar mass of barium (Ba) is 137.33 g/mol. Therefore, the number of moles of barium is:

moles of Ba = mass of Ba / molar mass of Ba = 10 g / 137.33 g/mol

Next, we can use the stoichiometry of the reaction to determine the number of moles of hydrogen gas produced. Since the ratio of barium to hydrogen gas is 1:1, the number of moles of hydrogen gas is equal to the number of moles of barium.

Finally, we can use the ideal gas law to calculate the volume of gas at standard temperature and pressure (STP). STP is defined as 1 atmosphere of pressure and 0 degrees Celsius (273.15 Kelvin).

The ideal gas law equation is:

PV = nRT

Where: P = pressure (in atmospheres) V = volume (in liters) n = number of moles R = ideal gas constant (0.0821 L·atm/(mol·K)) T = temperature (in Kelvin)

At STP, the pressure is 1 atmosphere and the temperature is 273.15 Kelvin. Therefore, we can rearrange the ideal gas law equation to solve for volume:

V = nRT / P = moles of H2 * 0.0821 L·atm/(mol·K) * 273.15 K / 1 atm

Let's calculate the volume of gas produced using these calculations.

Solution for C2:

To calculate the mass percentage of salt in the solution obtained by dissolving 105 g of potassium phosphate in 500 g of water, we need to determine the mass of the salt and the total mass of the solution.

The mass percentage is calculated using the formula:

Mass percentage = (mass of solute / mass of solution) * 100

In this case, the solute is potassium phosphate (K3PO4) and the solvent is water.

First, let's calculate the mass of the salt (K3PO4). The molar mass of potassium phosphate is:

molar mass of K3PO4 = (3 * atomic mass of K) + atomic mass of P + (4 * atomic mass of O)

Next, we can calculate the mass of the salt using the molar mass and the given amount:

mass of K3PO4 = (mass of K3PO4 / molar mass of K3PO4) * 105 g

Then, we need to calculate the total mass of the solution by adding the mass of the salt and the mass of water:

total mass of solution = mass of K3PO4 + mass of water = mass of K3PO4 + 500 g

Finally, we can calculate the mass percentage of the salt in the solution using the formula mentioned earlier:

mass percentage of salt = (mass of K3PO4 / total mass of solution) * 100

Let's calculate the mass percentage of the salt in the solution using these calculations.