Skip to main content
Ch.3 - Molecules, Compounds & Chemical Equations
Chapter 3, Problem 94

A 45.2-mg sample of phosphorus reacts with selenium to form 131.6 mg of the selenide. Determine the empirical formula of phosphorus selenide.

Verified Solution

Video duration:
2m
This video solution was recommended by our tutors as helpful for the problem above.
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 of a compound represents the simplest whole-number ratio of the elements present in that compound. It is determined by analyzing the relative amounts of each element in a sample. For example, if a compound contains 1 atom of phosphorus for every 2 atoms of selenium, its empirical formula would be PSe2.
Recommended video:
Guided course
02:26
Empirical vs Molecular Formula

Molar Mass and Conversion

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). To determine the empirical formula, it is essential to convert the mass of each element in the sample to moles using their respective molar masses. This conversion allows for the calculation of the ratio of the elements in the compound.
Recommended video:
Guided course
02:11
Molar Mass Concept

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It involves using balanced chemical equations to determine the amounts of substances consumed and produced. In this case, stoichiometry helps in calculating the moles of phosphorus and selenium to find their ratio in the empirical formula.
Recommended video:
Guided course
01:16
Stoichiometry Concept