Elemental phosphorus exists as molecules of P4. P4 combines with chlorine gas (Cl2) to form phosphorus pentachloride, according to the following unbalanced reaction:
P4 + Cl2 → PCl5
If 16.75 grams of P4 reacts completely to form PCl5, what is the percent yield for this reaction if 85.65 grams of PCl5 is formed?
NOTE: molar masses: P4 123.88 g/mol; PCl5 208.22 g/mol Your answer must include the percent sign (%) and contain the correct number of significant figures.

percentage yield = 76.06%

Explanation:

The reaction is between phosphorus molecule and chlorine molecule to form phosphorus pentachloride.

The chemical equation can be written as follows:

P4 + Cl2 → PCl5

The equation must be balanced to solve this problem

Balanced equation

P4 + 10Cl2 → 4PCl5

molar mass of P4 = 123. 88g/mol

molar mass of PCl5 = 208.22 g/mol

From the chemical reaction 1 mole of P4 produces 4 moles of PCl5

Therefore,

1 mole of P4 = 123. 88 g

4 mole of  PCl5 = 4 × 208.22  = 832.88 grams

So,

if 123.88 g of P4 produces 832.88 g of PCl5

16.75 g of P4 will produce ? grams of PCl5

cross multiply

Theoretical yield of  the reaction = (16.75 × 832.88)/123.88

Theoretical yield of  the reaction = 13950.74/123.88

Theoretical yield of  the reaction = 112.61494995

Theoretical yield of  the reaction = 112.61494995 g

percentage yield = actual yield/theoretical yield × 100

percentage yield = 85. 65/112.61494995 × 100

percentage yield = 8565/112.61494995

percentage yield = 76.055621423

percentage yield = 76.06%

The percent yield of this reaction is 76.07 %

Explanation:

Step 1: data given

Mass of P4 = 16.75 grams

MAss of PCL5 = 85.65 grams

Molar mass P4 = 123.88 g/mol

PCl5 = 208.22 g/mol

Step 2: The balanced equation

P4 + 10Cl2 → 4PCl5

Step 3: Calculate moles of P4

Moles P4 = mass P4 / molar mass P4

Moles P4 = 16.75 grams / 123.88 g/mol

Moles P4 = 0.1352 moles

Step 4: Calculate moles PCl5

For 1 mol P4 we need 10 moles Cl2 to produce 4 moles PCl5

For 0.1352 moles P4 we'll have 4*0.1352  = 0.5408 moles PCl5

Step 5: Calculate mass PCl5

Mass PCl5 = moles PCl5 * molar mass PCl5

Mass PCl5 = 0.5408 moles * 208.22 g/mol

Mass PCl5 = 112.6 grams

Step 6: Calculate the percent yield

Percent yield = (actual yileld / theoretical yield ) * 100 %

Percent yield = ( 85.65 grams / 112.6 grams ) *100%

Percent yield = 76.07 %

The percent yield of this reaction is 76.07 %