Question

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How many grams of HCl are produced if the following reaction yielded 27.7 grams of H3PO4?

Enter your answer in grams accurate to 3 significant figures. Do not include units as part of your answer.



PCl5 + H2O ⟶
H3PO4 + HCl (unbalanced)


Molar masses (in g mol−1):

H, 1.008 O, 16.00 P, 30.97 Cl, 35.45

I got 9.89grams of HCl

Answer 1

To determine the amount of HCl produced, we need to balance the chemical equation first. Here's the balanced equation:

PCl5 + 4 H2O ⟶ H3PO4 + 5 HCl

According to the balanced equation, for every mole of H3PO4 produced, 5 moles of HCl are formed. To find the number of moles of HCl, we need to convert the given mass of H3PO4 to moles using its molar mass.

Molar mass of H3PO4: (1 * 1.008) + (4 * 16.00) + 30.97 = 98.00 g/mol

Number of moles of H3PO4 = Mass of H3PO4 / Molar mass of H3PO4

Number of moles of H3PO4 = 27.7 g / 98.00 g/mol

Next, we use the mole ratio from the balanced equation to find the number of moles of HCl produced.

Number of moles of HCl = Number of moles of H3PO4 * (5 moles HCl / 1 mole H3PO4)

Finally, we convert the moles of HCl to grams by multiplying by its molar mass.

Molar mass of HCl: 1.008 + 35.45 = 36.46 g/mol

Mass of HCl = Number of moles of HCl * Molar mass of HCl

Now let's calculate the mass of HCl produced:

Number of moles of H3PO4 = 27.7 g / 98.00 g/mol = 0.283 moles

Number of moles of HCl = 0.283 moles * (5 moles HCl / 1 mole H3PO4) = 1.415 moles

Mass of HCl = 1.415 moles * 36.46 g/mol = 51.6 g

Therefore, approximately 51.6 grams of HCl are produced in the given reaction.