a) Tetraphosphorus (P4), commonly known as white phosphorus, forms different compounds with chlorine (Cl2) depending on the amount of chlorine present. If chlorine is limited, phosphorus trichloride (PCl3) is formed. If there is an excess of chlorine, phosphorus pentachloride (PCl5) is formed.Write balanced equations for the two reactions of white phosphorous with chlorine.

Question

b) Design an experiment that could be performed to verify each synthesis reaction. Include a hypothesis relating to whether PCl3 or PCl5 will be produced, information about the initial masses you would use, and possible problems that might arise.
c) Explain how your experiment will confirm the conservation of matter for each reaction.
d) Based on the ratio of moles of reactants in each case, predict the product of each trial of your experiment (PCl3 or PCl5) using your chosen initial masses. Explain your reasoning, and show any calculations.
e) Suppose you choose the initial masses so that both reactions produce PCl3. Explain how both of these chemical reactions obey the law of definite proportions, even though they produce different numbers of moles of the product. Justify your answer with calculations.

I need help with part b.

Answer 1

To follow up on Bob Pursley's response, you know the Cl2 will be the limiting reagent (unless of course you start with too much P4) but I would think you start with some amount of P4, use stoichiometry to add enough Cl2 to form PCl3 and do a separate calculation to see how much Cl2 to add for PCl5. The hypothesis should be centered around what the limiting reagent is and how that affects the yield of either PCl3 or PCl5. That should get you started.