Understanding the Reaction
To determine how many moles of potassium chloride (KCl) need to be heated to produce a specific volume of oxygen (O2), we first need to consider the decomposition reaction:
- 2 KCl(s) → 2 K(s) + Cl2(g)
In this reaction, potassium chloride decomposes to produce potassium and chlorine gas. However, oxygen is generally produced from other reactions, such as the decomposition of potassium chlorate (KClO3).
Relevant Reaction for Oxygen Production
The relevant decomposition reaction to produce oxygen is:
- 2 KClO3(s) → 2 KCl(s) + 3 O2(g)
This means that for every 2 moles of potassium chlorate decomposed, 3 moles of oxygen gas are produced.
Volume of Oxygen at NTP
At Normal Temperature and Pressure (NTP), 1 mole of any gas occupies 22.4 liters. Therefore, to find out how many moles of oxygen are in 11.2 liters, we can calculate:
- Moles of O2 = Volume of O2 / Volume of 1 mole at NTP = 11.2 L / 22.4 L/mol = 0.5 moles
Relating Moles of KClO3 to O2 Produced
From the balanced equation:
- 2 moles of KClO3 produce 3 moles of O2.
To find how many moles of KClO3 are needed to produce 0.5 moles of O2, we set up a proportion:
- (2 moles KClO3 / 3 moles O2) = (x moles KClO3 / 0.5 moles O2)
Solving for x gives:
- x = (0.5 moles O2 * 2 moles KClO3) / 3 = 1/3 moles KClO3
Conclusion
Therefore, the answer is:
- B. 1/3 moles of potassium chloride (in the form of KClO3) need to be heated to produce 11.2 liters of oxygen at NTP.