Question

A sample that contains only K₂CO₃ and Na₂CO₃ weighs 0.8824 g. When it is dissolved in excess acid, 0.3188 g of carbon dioxide is liberated. What percentage of K2CO3 did the sample contain? Assume all the carbon originally present is converted to carbon dioxide.

Mass percent K₂CO₃ = ... %

Answer 1

To find the percentage of K₂CO₃ in the sample, we calculate the mass of K₂CO₃ and the total mass of the sample. Using the molar mass of K₂CO₃ and the molar ratio of K₂CO₃ to CO₂, we find that the sample contains 113.7% K₂CO₃.

Step-by-step explanation:

To find the percentage of K₂CO₃ in the sample, we need to determine the amount of K₂CO₃ present and the total mass of the sample. We can do this by calculating the molar mass of K₂CO₃ and using the molar ratio of K₂CO₃ to CO₂ in the reaction.

The molar mass of K₂CO₃ can be calculated as:

1. Molar mass of K = 39.10 g/mol
2. Molar mass of C = 12.01 g/mol
3. Molar mass of O = 16.00 g/mol

Therefore, the molar mass of K₂CO₃ = (2 * 39.10) + 12.01 + (3 * 16.00) = 138.21 g/mol.

Next, we can use the molar ratio of K₂CO₃ to CO₂ in the reaction to find the amount of K₂CO₃ in the sample:

Molar ratio of K₂CO₃ to CO₂ = 1:1

Amount of K₂CO₃ = Amount of CO₂ = 0.3188 g

Now we can calculate the mass of K₂CO₃ in the sample:

Mass of K₂CO₃ = (Amount of K₂CO₃ / Molar mass of K₂CO₃) * Molar mass of K₂CO₃

Mass of K₂CO₃ = (0.3188 g / 44.01 g/mol) * 138.21 g/mol = 1.002 g

Finally, we can calculate the percentage of K₂CO₃ in the sample:

Percentage of K₂CO₃ = (Mass of K₂CO₃ / Total mass of the sample) * 100%

Percentage of K₂CO₃ = (1.002 g / 0.8824 g) * 100% = 113.7%