Chapter 8: Problem 38
What is the oxidation state of \(\mathrm{P}\) in \(\mathrm{Ba}\left(\mathrm{H}_{2} \mathrm{PO}_{2}\right)_{2} ?\) (a) \(+3\) (b) \(+2\) (c) \(+1\) (d) \(-1\)
Short Answer
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Step by step solution
01
Understanding the concept of oxidation states
The oxidation state, or oxidation number, is a measure of the degree of oxidation of an atom in a chemical compound. It is defined as the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. The sum of the oxidation states for all atoms in a neutral molecule must be zero.
02
Assign oxidation states to known elements
In the compound \(\mathrm{Ba}(\mathrm{H}_2 \mathrm{PO}_2)_2\), barium (Ba) is in Group 2 and typically has an oxidation state of +2. Hydrogen (H) typically has an oxidation state of +1 in most compounds. Oxygen (O) typically has an oxidation state of -2.
03
Determine the total oxidation states from known elements
There are two hydrogen atoms bonded to phosphorus, contributing a total of +2, and two oxygen atoms bonded to phosphorus, contributing a total of -4 to the oxidation state of phosphorus.
04
Calculate the oxidation state of phosphorus (P)
Let the oxidation state of phosphorus be x. The compound is neutral, so the sum of the oxidation states should be zero: \[ +2 + 2(+1) + x + 2(-2) = 0 \]. Simplifying this equation gives: \[ 2 + 2x - 4 = 0 \], which simplifies further to \[ 2x - 2 = 0 \]. Solving for x gives \[ x = +1 \(\text{the oxidation state of phosphorus}\). \]
05
Verify with the multiple-choice options
Compare the calculated oxidation state of phosphorus (P) with the provided answer choices. The correct option is the one that matches the calculated oxidation state.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Oxidation Number Determination
Understanding how to determine the oxidation number, or oxidation state, of an element within a compound is fundamental in chemistry, particularly when dealing with redox reactions.
The oxidation number represents the number of electrons an atom might gain or lose if it were to react, or the theoretical charge an atom would hold if the compound was made up of ions.
To determine oxidation numbers, we follow a set of rules: Elements in their elemental form always have an oxidation number of 0. For ions composed of only one atom, the oxidation state is equal to the charge on the ion. For example, sodium (Na) in NaCl has an oxidation state of +1. The sum of oxidation numbers in a neutral compound must be zero, and in a polyatomic ion, the sum must equal the charge of the ion.
For example, in \(\mathrm{Ba}(\mathrm{H}_2 \mathrm{PO}_2)_2\), barium's (Ba) oxidation number is +2, hydrogen's (H) is +1 (except when bonded to metals in hydrides, where it is -1), and oxygen's (O) is typically -2. Using these rules along with the known oxidation states of hydrogen and oxygen, we can determine the oxidation state of phosphorus (P) in the compound to ensure the total equals zero for a neutral molecule.
The oxidation number represents the number of electrons an atom might gain or lose if it were to react, or the theoretical charge an atom would hold if the compound was made up of ions.
To determine oxidation numbers, we follow a set of rules: Elements in their elemental form always have an oxidation number of 0. For ions composed of only one atom, the oxidation state is equal to the charge on the ion. For example, sodium (Na) in NaCl has an oxidation state of +1. The sum of oxidation numbers in a neutral compound must be zero, and in a polyatomic ion, the sum must equal the charge of the ion.
For example, in \(\mathrm{Ba}(\mathrm{H}_2 \mathrm{PO}_2)_2\), barium's (Ba) oxidation number is +2, hydrogen's (H) is +1 (except when bonded to metals in hydrides, where it is -1), and oxygen's (O) is typically -2. Using these rules along with the known oxidation states of hydrogen and oxygen, we can determine the oxidation state of phosphorus (P) in the compound to ensure the total equals zero for a neutral molecule.
Chemical Compound Valency
The valency of a chemical element is the measure of its combining power with other atoms when it forms chemical compounds or molecules.
The valency is related to the number of electrons that an atom can lose, gain, or share with other atoms. It is determined based on the element's position in the periodic table, particularly the number of electrons in its outer shell.
Groups 1, 2, and 13 to 18 respectively have valencies of 1, 2, and 3 to 8 (skipping the transition metals). For example, the element oxygen has six electrons in its outer shell and commonly has a valency of two, meaning it tends to form two bonds with other atoms.
Valency plays a crucial role when determining the formulas of compounds and how atoms connect. In our exercise, the phosphorus atom bonding with two hydrogen and two oxygen atoms reflects the concept of valency in how these atoms share electrons to form stable bonds. Understanding valency helps to predict the structure of molecules and the outcomes of chemical reactions.
The valency is related to the number of electrons that an atom can lose, gain, or share with other atoms. It is determined based on the element's position in the periodic table, particularly the number of electrons in its outer shell.
Groups 1, 2, and 13 to 18 respectively have valencies of 1, 2, and 3 to 8 (skipping the transition metals). For example, the element oxygen has six electrons in its outer shell and commonly has a valency of two, meaning it tends to form two bonds with other atoms.
Valency plays a crucial role when determining the formulas of compounds and how atoms connect. In our exercise, the phosphorus atom bonding with two hydrogen and two oxygen atoms reflects the concept of valency in how these atoms share electrons to form stable bonds. Understanding valency helps to predict the structure of molecules and the outcomes of chemical reactions.
Balancing Oxidation States
Balancing oxidation states is essential in chemistry, particularly when working with redox (reduction-oxidation) reactions. When elements undergo chemical reactions, the oxidation states can change, with some atoms losing electrons (oxidation) and others gaining electrons (reduction).
To balance oxidation states in a compound, you must consider both the overall charge of the compound (which must be zero for neutral compounds or equal to the charge for ions) and the typically observed oxidation states of its constituent elements.
In the case of \(\mathrm{Ba}(\mathrm{H}_2 \mathrm{PO}_2)_2\), by knowing the oxidation states of barium, hydrogen, and oxygen, we calculate the oxidation state of phosphorus such that the sum of all oxidation states in the compound equals zero. This is an application of the principle of charge neutrality. By balancing the oxidation states, we ensure the chemical equation adheres to the law of conservation of charge, a fundamental rule in chemistry indicating that charge can neither be created nor destroyed.
To balance oxidation states in a compound, you must consider both the overall charge of the compound (which must be zero for neutral compounds or equal to the charge for ions) and the typically observed oxidation states of its constituent elements.
In the case of \(\mathrm{Ba}(\mathrm{H}_2 \mathrm{PO}_2)_2\), by knowing the oxidation states of barium, hydrogen, and oxygen, we calculate the oxidation state of phosphorus such that the sum of all oxidation states in the compound equals zero. This is an application of the principle of charge neutrality. By balancing the oxidation states, we ensure the chemical equation adheres to the law of conservation of charge, a fundamental rule in chemistry indicating that charge can neither be created nor destroyed.
