Question

При обработке 300 г древесной золы избытком соляной кислоты,получили 44,8л(н.у) углекислого газа.Какова массова доля(%)карбоната калия в исходном образе золы

Answer 1

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Answer 2

Calculation of the Mass Percentage of Potassium Carbonate in the Ash

To calculate the mass percentage of potassium carbonate in the ash, we need to use the given information about the volume of carbon dioxide produced during the reaction.

According to the information provided, when 300 g of wood ash was treated with an excess of hydrochloric acid, 44.8 liters of carbon dioxide gas were produced at normal conditions (n.у).

To calculate the mass percentage of potassium carbonate, we need to determine the amount of carbon dioxide produced and then relate it to the amount of potassium carbonate present in the ash.

Calculation Steps:

1. Convert the volume of carbon dioxide gas to the number of moles using the ideal gas law. 2. Use the balanced chemical equation to determine the mole ratio between carbon dioxide and potassium carbonate. 3. Calculate the number of moles of potassium carbonate. 4. Determine the mass of potassium carbonate. 5. Calculate the mass percentage of potassium carbonate in the ash.

Let's proceed with the calculations:

Step 1: Convert the volume of carbon dioxide gas to moles.

To convert the volume of carbon dioxide gas to moles, we need to use the ideal gas law equation:

PV = nRT

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

Since the pressure and temperature are not given, we can assume standard conditions (1 atm and 273 K).

Using the given volume of 44.8 liters, we can calculate the number of moles of carbon dioxide:

n = PV / RT n = (1 atm) * (44.8 L) / (0.0821 L·atm/mol·K * 273 K) n ≈ 1.97 moles

Step 2: Determine the mole ratio between carbon dioxide and potassium carbonate.

The balanced chemical equation for the reaction between hydrochloric acid and potassium carbonate is:

2 HCl + K2CO3 → 2 KCl + H2O + CO2

From the balanced equation, we can see that 1 mole of potassium carbonate produces 1 mole of carbon dioxide.

Step 3: Calculate the number of moles of potassium carbonate.

Since 1 mole of potassium carbonate produces 1 mole of carbon dioxide, the number of moles of potassium carbonate is also approximately 1.97 moles.

Step 4: Determine the mass of potassium carbonate.

To calculate the mass of potassium carbonate, we need to know its molar mass. The molar mass of potassium carbonate (K2CO3) is:

K: 39.10 g/mol C: 12.01 g/mol O: 16.00 g/mol

Molar mass of K2CO3 = (2 * 39.10 g/mol) + 12.01 g/mol + (3 * 16.00 g/mol) ≈ 138.21 g/mol

Mass of potassium carbonate = number of moles * molar mass Mass of potassium carbonate = 1.97 moles * 138.21 g/mol ≈ 272.16 g

Step 5: Calculate the mass percentage of potassium carbonate in the ash.

The mass percentage is calculated by dividing the mass of potassium carbonate by the mass of the ash and multiplying by 100:

Mass percentage = (mass of potassium carbonate / mass of ash) * 100 Mass percentage = (272.16 g / 300 g) * 100 ≈ 90.72%

Therefore, the mass percentage of potassium carbonate in the original wood ash is approximately 90.72%.

Please note that these calculations are based on the given information and assumptions made.