A copper wire having a mass of 2.196 g was allowed to react with an excess of sulfur. The excess

step 1 For Part A, we're asked, what is the composition of copper sulfide? So we have the mass of coppe

A copper wire having a mass of 2.196 g was allowed to react...

A copper wire having a mass of 2.196 $\mathrm{g}$ was allowed to react with an excess of sulfur. The excess sulfur was then burned, yielding $\mathrm{SO}_{2}$ gas. The mass of the copper sulfide produced was 2.748 $\mathrm{g}$ (a) What is the percent composition of copper sulfide? (b) What is its empirical formula? (c) Calculate the number of copper ions per cubic centimeter if the density of the copper sulfide is 5.6 $\mathrm{g} / \mathrm{cm}^{3}$ .

A copper wire having a mass of 2.196 $\mathrm{g}$ was allowed to react with an excess of sulfur. The excess sulfur was then burned, yielding $\mathrm{SO}_{2}$ gas. The mass of the copper sulfide produced was 2.748 $\mathrm{g}$
(a) What is the percent composition of copper sulfide?
(b) What is its empirical formula?
(c) Calculate the number of copper ions per cubic centimeter if the density of the copper sulfide is 5.6 $\mathrm{g} / \mathrm{cm}^{3}$ .

Key Concepts

Percent Composition

Percent composition refers to the percentage by mass of each element in a compound. It is calculated by dividing the mass of the individual element by the total mass of the compound, then multiplying by 100. This concept is crucial for understanding the makeup of chemical compounds and for performing quantitative analyses in chemistry.

Empirical Formula Determination

Determining the empirical formula involves finding the simplest whole-number ratio of atoms of each element in a compound. This is typically done by converting the masses of each element to moles and then dividing by the smallest number of moles present, which provides insight into the fundamental composition of the substance.

Stoichiometry

Stoichiometry is the study of the quantitative relationships between reactants and products in a chemical reaction. It encompasses using measurements of mass, moles, and mole ratios to predict the amounts of substances consumed and produced in chemical reactions, and is essential for interpreting experimental results.

Density and Volume Relations

Density is a measure of mass per unit volume and is used to relate the mass of a substance to the space it occupies. In problems involving density, one often calculates the volume of a material from its mass, which is a key step in determining parameters like ion concentration or number density in a given volume.

Mole Concept and Avogadro's Number

The mole concept allows chemists to count particles, such as atoms or ions, using the unit 'mole', which represents a fixed number of particles (Avogadro's number, approximately 6.022 × 10^23). This is fundamental in converting between the mass of a substance and the number of individual ions or atoms it contains, facilitating the calculation of number densities and other related quantities.

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