Question

When \(4.90 \mathrm{~g}\) of \(\mathrm{KCLO}_{3}\) was heated, it showed a weight loss of \(0.384 \mathrm{~g}\). Find the percent of the original \(\mathrm{KCLO}_{3}\) that had decomposed.

Short answer

The percentage of the original KCLO3 that decomposed is 7.84%.

Step-by-step solution

Identify the given information

First, let's identify the given information: - Initial mass of KCLO3 (m1) = 4.90 g - Mass lost after heating (m2) = 0.384 g

Calculate the percentage of decomposition

Next, we will calculate the percentage of decomposition by dividing the mass lost (m2) by the initial mass (m1), and multiply the result by 100: Percentage of decomposition = \(\frac{m2}{m1} × 100\) Plug in given values: Percentage of decomposition = \(\frac{0.384}{4.90} × 100\)

Solve for the percentage

Now, we will perform the calculation: Percentage of decomposition = \(\frac{0.384}{4.90} × 100 = 7.84\%\) Thus, 7.84% of the original KCLO3 had decomposed after heating.

Key concepts

Weight Loss Calculation

Weight loss calculation in chemical processes often involves identifying the amount of material that changes state or form after a reaction. In decomposition reactions, we typically measure the initial mass of a substance before the reaction and the mass lost after the reaction.
To illustrate this, consider the given problem where we have an initial mass, denoted as \( m_1 = 4.90 \text{ g} \), and the mass lost after heating, denoted as \( m_2 = 0.384 \text{ g} \). The weight loss is the difference between these two values. However, for percentage calculations, we directly use the mass lost \( m_2 \) as part of the formula.

• Identify initial and final masses.
• Use the formula: \( \text{Weight loss percentage} = \frac{\text{mass lost}}{\text{initial mass}} \times 100 \).

Computing these values allows us to understand the extent of decomposition or reaction that has occurred.

Percentage Composition

Percentage composition is a way to express the relative amounts of each component in a compound. In our exercise, we use it to understand how much of the total compound has decomposed in percentage terms. This involves expressing the mass lost as a portion of the initial total mass, multiplied by 100 to convert it into a percentage. Using the problem’s dataset:
- Initial mass of \( \text{KCLO}_3 \) is \( 4.90 \text{ g} \).- Mass lost is \( 0.384 \text{ g} \).Hence, the percentage that has decomposed is calculated using:\[\text{Percentage decomposition} = \left( \frac{0.384}{4.90} \right) \times 100 \]The result, \( 7.84\% \), indicates that a small fraction of the original substance changed during heating. Knowing this helps chemists control reaction scales and predict yields.

Stoichiometry

Stoichiometry is the area of chemistry that involves calculating the quantities of reactants and products in chemical reactions. In decomposition reactions, stoichiometry helps us grasp how substances break down into simpler compounds or elements.When \( \text{KCLO}_3 \) is heated, it decomposes into potassium chloride (KCl) and oxygen gas (O₂). Here’s a simplified breakdown of what happens:

• KCLO₃ \( \rightarrow \) KCl + O₂
• The stoichiometric coefficients indicate the number of moles of each substance involved in the reaction.

Understanding stoichiometry affords chemists the ability to calculate exact amounts of reactants and predict the products formed. In this exercise, we didn’t delve into balancing equations or deep details of stoichiometry, but these principles underscore the calculated percentage decomposition we approached.