(b) An elemental analysis of the acid indicates that it is composed of 5.89% H, 70.6% C, and 23.5% O by mass. What is its molecular formula?

Verified step by step guidance

Step 1: Assume that you have 100 g of the compound. This means that you have 5.89 g of Hydrogen (H), 70.6 g of Carbon (C), and 23.5 g of Oxygen (O).

Step 2: Convert these masses into moles using the molar mass of each element. The molar mass of H is approximately 1 g/mol, the molar mass of C is approximately 12 g/mol, and the molar mass of O is approximately 16 g/mol.

Step 3: Divide each mole value by the smallest number of moles calculated. This will give you the mole ratio of H, C, and O in the compound.

Step 4: If the mole ratios are not whole numbers, multiply them by the smallest number that will convert them all to whole numbers. This will give you the empirical formula of the compound.

Step 5: To find the molecular formula, you need to know the molar mass of the compound. Divide the molar mass of the compound by the molar mass of the empirical formula. This will give you a whole number, which you multiply by the subscripts in the empirical formula to get the molecular formula.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Empirical Formula

The empirical formula represents the simplest whole-number ratio of the elements in a compound. To determine the empirical formula from percentage composition, one converts the percentages to moles by dividing by the atomic masses of the elements. This ratio helps in identifying the basic composition of the compound before determining the molecular formula.

Molecular Formula

The molecular formula indicates the actual number of atoms of each element in a molecule of a compound. It can be derived from the empirical formula by multiplying it by a whole number, which is determined by comparing the molar mass of the compound to the molar mass of the empirical formula. This formula provides more specific information about the compound's structure.

Molar Mass Calculation

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). To find the molecular formula, one must first calculate the molar mass of the compound using the atomic masses of its constituent elements. This value is essential for determining the relationship between the empirical and molecular formulas.

Recommended video:

Guided course

03:12

Molar Mass Calculation Example

Related Practice

Textbook Question

(a) By titration, 15.0 mL of 0.1008 M sodium hydroxide is needed to neutralize a 0.2053-g sample of a weak acid. What is the molar mass of the acid if it is monoprotic?

Textbook Question

A solid sample of Zn(OH)2 is added to 0.350 L of 0.500 M aqueous HBr. The solution that remains is still acidic. It is then titrated with 0.500 M NaOH solution, and it takes 88.5 mL of the NaOH solution to reach the equivalence point. What mass of Zn(OH)2 was added to the HBr solution?

Textbook Question

A sample of 7.75 g of Mg(OH)2 is added to 25.0 mL of 0.200 𝑀 HNO3. c. How many moles of Mg(OH)2,HNO3, and Mg(NO3)2 are present after the reaction is complete?

Textbook Question

Suppose you have 5.00 g of powdered magnesium metal, 1.00 L of 2.00 M potassium nitrate solution, and 1.00 L of 2.00 M silver nitrate solution. d. What is the molarity of the Mg2+ ions in the resulting solution?

Textbook Question

Suppose you have 5.00 g of powdered magnesium metal, 1.00 L of 2.00 M potassium nitrate solution, and 1.00 L of 2.00 M silver nitrate solution. a. Which one of the solutions will react with the magnesium powder?