Concept explainers
The police often use a device called a Breatkalyzer to test drivers suspected of being drunk. In one type of device, the breath of a driver suspected of driving under the influence of alcohol is bubbled through an orange solution containing potassium dichromate
(a) Classify each of the species in the Breathalyzer reaction as a strong electrolyte, weak electrolyte, or nonelectrolyte, (b) Write the ionic and net ionic equations for the Breathahzer reaction. (c) Determine the oxidation number of each element in the overall equation. (d) One manufacturer of Breathalyzers specifies a potassium dichromate concentration of 0.025 percent weight per volume
Interpretation:
The reactants and products in breathalyzer are to be classified as strong, weak, or non-electrolyte, the ionic and the net ionic equation for the reaction are to be represented, and the oxidation state of each element is to be determined in the reaction. The concentration of potassium dichromate in molarity is to be expressed and the volume of stock solution of
Concept introduction:
An electrolyte is a compound which dissociates into its corresponding ions when dissolved in water and conducts electricity. Electrolytes can be strong, weak, or non-electrolyte. The classification of the type of electrolyte is based on the formation of the ions when the electrolyte is dissolved in water.
An ionic reaction always follows the law of conservation of mass, according to which, when a chemical reaction occurs, the mass of ions in products should be equal to the mass of ions in reactants.
Oxidation number is the net charge on an element involved in the formation of a compound in a reaction. It is also known as oxidation state.
The concentration of a solution in terms of molarity is determined as follows:
Here,
Dilution is the process by which a less concentrated solution can be prepared from a more concentrated solution. But, the number of moles of solute remains the same in the original solution and the dilution. So, the concentration or volume of dilution can be determined as follows:
Here,
in ml,
Answer to Problem 159AP
Solution:
a)
b)
Ionic equation for breathalyzer is as follows:
The net ionic equation is as follows:
c)
Oxidation states of reactants and products are:
d)
The molar concentration of
e)
The volume of
f)
The molarity of
Explanation of Solution
a)
Given information: The reaction for breathalyzer is as follows:
a) Classify each of the species in the Breathalyzer reaction as a strong electrolyte, weak electrolite or nonelectrolyte.
b) The ionic and net ionic equations for the Breathalyzer reaction.
The ionic equation for the breathalyzer reaction is as follows:
The net ionic equation for the breathalyzer reaction is as follows:
c) The oxidation number of each element in the overall equation.
The oxidation numbers of elements in
The oxidation numbers of elements in
The oxidation numbers of elements in
The oxidation numbers of elements in
The oxidation numbers of elements in
The oxidation numbers of elements in
The oxidation numbers of elements in
d) The concentration in terms of molarity for the reaction
The concentration of
The molecular weight of
Substitute the values in the equation as follows:
e) The volume of
The concentration of stock solution is
Consider the two solutions, the stock solution is solution
Rearranging the equation to calculate the volume as follows:
f) The molarity of each ion in a
Potassium dichromate form the following ions on dissolution:
So, the concentration of these ions is as follows:
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