Question

A mixture of KClO3 and KCl with a mass of 0.950 g was heated to produce O2. After heating, the mass of residue was 0.820 g. Assuming all the KClO3 decomposed to KCl and O2, calculate the mass percent of KClO3 in the original mixture.

Answer 1

The mass percent of KClO3 in the original mixture is calculated to be 13.68%, based on the mass of oxygen gas released upon the decomposition of potassium chlorate.

Step-by-step explanation:

To calculate the mass percent of KClO3 in the original mixture, you need to determine the mass of KClO3 that decomposed to make the measured residue of KCl. Given that the mass of the mixture before heating was 0.950 g and the mass after heating was 0.820 g, the mass of the oxygen gas released is the difference between these two masses, which is 0.950 g - 0.820 g = 0.130 g.

The reaction for the decomposition of potassium chlorate (KClO3) is already balanced as shown:

• 2 KClO3 (s) → 2 KCl (s) + 3 O2 (g)

Since the mass of KCl does not change during the reaction, the initial mass of KClO3 in the mixture equals the mass of oxygen gas produced. Thus, the mass percent of KClO3 in the original mixture can be calculated as:

(Mass of KClO3 / Total mass of mixture) × 100%

(0.130 g / 0.950 g) × 100% = 13.68%

Hence, the mass percent of potassium chlorate in the original mixture is 13.68%.

Answer 2

Step-by-step explanation:

The given reaction will be as follows.

`KClO_(3)(s) \rightarrow KCl(s) + (3)/(2)O_(2)(g)`

Molar mass of
`KClO_(3)` = 122.5 g/mol

Molar mass of KCl = 74.5 g/mole

Molar mass of
`O_(2)` = 32 g/mole

We assume that the mass of
`KClO_(3)` in the sample be x g

Therefore, the mass of KCl in the sample = 0.95 - x

Hence, moles of
`KClO_(3)` =
`(x)/(122.5)`

So, moles of KCl produced = moles of
`KClO_(3)` =
`(x)/(122.5)`

or, mass of KCl produced =
`((x)/(122.5) ) * 74.5`

Therefore, total mass of KCl = mass of residue = (0.95 - x) +
`{((x)/(122.5)) * 74.5}` = 0.820 g

-0.39x = 0.820 - 0.95

x = 0.33

Thus, % of
`KClO_(3)` in the original sample will be calculated as follows.

`(x)/(0.95) * 100`

= 34.73%

Thus, we can conclude that mass % of
`KClO_(3)` is 34.73%.