Question

If you have equal-mole samples of each of the following compounds, which compound contains the greatest number of oxygen atoms? a. magnesium nitrate b. dinitrogen pentoxide c .$ iron(III) phosphate d. barium oxide e. potassium acetate

Short answer

In one mole of each compound, magnesium nitrate \(Mg(NO_3)_2\) contains 6 oxygen atoms, dinitrogen pentoxide \(N_2O_5\) has 5 oxygen atoms, iron(III) phosphate \(FePO_4\) has 4 oxygen atoms, barium oxide \(BaO\) has 1 oxygen atom, and potassium acetate \(KC_2H_3O_2\) has 2 oxygen atoms. Therefore, the compound with the greatest number of oxygen atoms in equal-mole samples is magnesium nitrate.

Step-by-step solution

Identify chemical formulas for each compound

We first need to determine the chemical formulas of each of the given compounds. a. Magnesium nitrate: Mg(NO3)2 b. Dinitrogen pentoxide: N2O5 c. Iron(III) phosphate: FePO4 d. Barium oxide: BaO e. Potassium acetate: KC2H3O2

Count the number of oxygen atoms in each compound

Now, we can count the number of oxygen atoms in one mole of each compound based on their chemical formula: a. Magnesium nitrate: Mg(NO3)2 - There are 2 (NO3) groups, each with 3 oxygen atoms, so there are a total of 2*3 = 6 oxygen atoms. b. Dinitrogen pentoxide: N2O5 - There are 5 oxygen atoms. c. Iron(III) phosphate: FePO4 - There are 4 oxygen atoms. d. Barium oxide: BaO - There is 1 oxygen atom. e. Potassium acetate: KC2H3O2 - There are 2 oxygen atoms.

Compare the number of oxygen atoms and find the greatest

We now compare the number of oxygen atoms in one mole of each compound: a. Magnesium nitrate: 6 oxygen atoms b. Dinitrogen pentoxide: 5 oxygen atoms c. Iron(III) phosphate: 4 oxygen atoms d. Barium oxide: 1 oxygen atom e. Potassium acetate: 2 oxygen atoms From this comparison, we can see that magnesium nitrate (a) has the greatest number of oxygen atoms (6). So, the compound with the greatest number of oxygen atoms in equal-mole samples is magnesium nitrate.

Key concepts

Stoichiometry

Understanding stoichiometry is crucial for solving many problems in chemistry, such as determining reactant quantities in reactions or, as in our exercise, comparing elements in different compounds. Stoichiometry is the branch of chemistry that deals with the relative quantities of reactants and products in chemical reactions. It's based on the conservation of mass where the total mass of the reactants equals the total mass of the products.

For students grappling with stoichiometry, it's essential to grasp that it involves calculations using the relationships derived from the balanced chemical equations of substances. This includes the mole concept, which measures substances based on how many particles they contain, not their weight – a concept that is vital for comparing amounts in various compounds, as demonstrated in the exercise's solution.

The task was to identify which compound had the greatest number of oxygen atoms per mole. The process neatly combined stoichiometry with the mole concept, requiring the counting of oxygen atoms in the formula unit of each compound. Simplifying the compound into its base components and using the coefficients and subscripts in chemical formulas, we were able to perform comparative analysis effectively.

Chemical Formulas

Chemical formulas represent a very concise way of providing a wealth of information about a compound. For instance, the formula for magnesium nitrate, Mg(NO3)2, not only tells us which elements are present – magnesium, nitrogen, and oxygen – but also the exact ratio in which the atoms combine. This understanding forms the crux of solving the exercise.

To improve comprehension, it's important to understand the language of these formulas. The numbers after symbols (subscripts) indicate the number of atoms of that element in one molecule or formula unit of the compound. Moreover, parentheses are used in chemical formulas to indicate a group of atoms that behave as a unit and are present multiple times in the molecule. For example, in Mg(NO3)2, the '(NO3)2' component signifies two nitrate groups, each contributing three oxygen atoms, leading us to a count of six oxygen atoms in total.

Decoding chemical formulas is not just about understanding the letters and numbers, but also about visualizing how these atoms are arranged and interact in three-dimensional space, which can be especially enlightening when comparing compounds.

Comparative Analysis of Compounds

The exercise required a comparative analysis to determine which compound had the most of a specific element – oxygen, in this case. Comparative analysis in chemistry often involves looking at different compounds side by side to draw conclusions about their properties or behaviors. For example, by knowing the chemical formulas of each compound and understanding how to count atoms in these formulas, we can perform a quantitative comparison.

It's important to approach this systematically. As illustrated in the solution, we first identified the chemical formula for each compound and then focused on counting a specific element, employing the mole concept to ensure a fair comparison. Given that a mole is a standard unit in chemistry to express amounts of a chemical substance, this method ensures that the comparison is based on an equal-mole basis.

In practical terms, this means not getting distracted by the weights or volumes of the compounds. Instead, concentrate on the number of moles, because a single mole of any compound will always contain the same number of molecules (Avogadro's number), allowing for direct comparison of the number of atoms of one type across different compounds.