Balancing Chemical Equations with Chlorine

Dr. B demonstrates how to balance the chemical equation of phosphorus and chlorine gas yielding phosphorus pentachloride. The process involves identifying the number of atoms on each side, adjusting coefficients to balance chlorine atoms, and then balancing phosphorus atoms. The key challenge is resolving the odd and even numbers of chlorine atoms, which is achieved by multiplying the phosphorus pentachloride by 2. This results in a balanced equation with even numbers of atoms on both sides.

What is the chemical equation that needs to be balanced in the video?

• Phosphorus plus hydrogen yields phosphine

• Phosphorus plus chlorine gas yields phosphorus pentachloride

• Phosphorus plus nitrogen yields phosphorus nitride

• Phosphorus plus oxygen yields phosphorus pentoxide

How many chlorine atoms are present on the product side initially?

• Three

• Four

• Two

• Five

What is the first step taken to resolve the odd number of chlorine atoms?

• Multiply phosphorus pentachloride by 2

• Remove some chlorine atoms

• Add more phosphorus atoms

• Add more chlorine gas

After multiplying phosphorus pentachloride by 2, how many chlorine atoms are there on the product side?

• Ten

• Six

• Eight

• Twelve

What coefficient is placed in front of chlorine gas to balance the chlorine atoms?

• 5

• 4

• 3

• 6

How many phosphorus atoms are needed on the reactant side to balance the equation?

• One

• Two

• Three

• Four

What is the key observation that helps in balancing the equation?

• The even number of phosphorus atoms

• The number of hydrogen atoms

• The presence of oxygen atoms

• The odd number of chlorine atoms

What is the final balanced equation for the reaction?

• 2P + 4Cl2 → 2PCl4

• 2P + 5Cl2 → 2PCl5

• P + 3Cl2 → PCl3

• P + 2Cl2 → PCl4