Chapter 3: Q 38E (page 169)

Question-Determine the empirical formulas for the compounds with the following percentage composition:
(a) 43.6% phosphorous and 56.4% oxygen
(b) 28.7%K, 1.5%H, 22.8%P and 47%O

Short Answer

Expert verified

(a) The empirical formula for the compound having 43.6% phosphorous and 56.4% oxygen is P₂O₅

(b) The empirical formula for the compound having 28.7% K, 1.5%H, 22.8% P, and 47% O is KH₂PO₄

Step by step solution

Step 1-Given data in subpart (a).

Mass of phosphorous = 43.6g

Mass of oxygen = 56.4g

Step 2- Calculating moles in subpart (a)

Moles = Mass/molar mass

For phosphorus = 43.6/31 = 1.41mol

For oxygen = 56.4/16 = 3.53mol

Dividing each mole by the smallest value, we get

P= 1.41/1.41 = 1mol

O = 3.53/1.41 = 2.5 mol

Multiply each ratio by 2 to get an approximate value, we get

P = 1 x 2 = 2mol

O = 2.5 x 2 = 5mol

So, the empirical formula is P₂O₅

Step 3- Given data in subpart (b)

Mass of K = 28.7g

Mass of H = 1.5g

Mass of P = 22.8g

Mass of O = 47g

Step 4- Calculating moles in subpart (d)

Moles = given mass/molecular mass

Moles of K = 28.7/39.1 =0.73mol

Moles of H = 1.5/1= 1.5mol

Moles of P =22.8/31 = 0.74mol

Moles of O = 47/16 = 2.9mol

For the ratio of all we multiply it by 4, and we get

3:6:3:12 this can be simplified more so we get 1:2:1:4

So, the empirical formula is KH₂PO₄

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Question-Determine the empirical formulas for the compounds with the following percentage composition:
(a) 43.6% phosphorous and 56.4% oxygen
(b) 28.7%K, 1.5%H, 22.8%P and 47%O

Short Answer

Step by step solution

Step 1-Given data in subpart (a).

Step 2- Calculating moles in subpart (a)

Step 3- Given data in subpart (b)

Step 4- Calculating moles in subpart (d)

One App. One Place for Learning.

Most popular questions from this chapter

A cough syrup contains 5.0% ethyl alcohol C₂H₅OH, by mass. If the density of the solution is 0.9928 g/ml determine the molarity of alcohol in the cough syrup.

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Question-Determine the empirical formulas for the compounds with the following percentage composition:(a) 43.6% phosphorous and 56.4% oxygen(b) 28.7%K, 1.5%H, 22.8%P and 47%O

Short Answer

Step by step solution

Step 1-Given data in subpart (a).

Step 2- Calculating moles in subpart (a)

Step 3- Given data in subpart (b)

Step 4- Calculating moles in subpart (d)

One App. One Place for Learning.

Most popular questions from this chapter

A cough syrup contains 5.0% ethyl alcohol C2H5OH, by mass. If the density of the solution is 0.9928 g/ml determine the molarity of alcohol in the cough syrup.

Recommended explanations on Chemistry Textbooks

Ionic and Molecular Compounds

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Kinetics

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Nuclear Chemistry

Inorganic Chemistry

Study anywhere. Anytime. Across all devices.

Question-Determine the empirical formulas for the compounds with the following percentage composition:
(a) 43.6% phosphorous and 56.4% oxygen
(b) 28.7%K, 1.5%H, 22.8%P and 47%O

A cough syrup contains 5.0% ethyl alcohol C₂H₅OH, by mass. If the density of the solution is 0.9928 g/ml determine the molarity of alcohol in the cough syrup.