A bicycle rusting after it is left in the rain is an example of a chemical reaction because it involves oxidation (Option d).
<h3>What is a chemical reaction?</h3>
A chemical reaction can be defined as a phenomenon in which one or more substances called reactants react to form one or more different compounds, which are known as products.
A chemical reaction may include an enzyme that works to increase the seed of the reaction in normal conditions by lowering the activation energy of the reaction.
Therefore, we can conclude that a chemical reaction such as oxidation in a bicycle is a process where reactants combine or break down to form the products of such reaction.
Complete question:
Which of the following situations contains an example of a chemical reaction?
a. Ice forming after water is placed in a freezer
b. Watercolor paint drying on paper
c. a sugar cube dissolving in a glass of water
d. a bicycle rusting after it is left in the rain
Learn more about chemical reactions here:
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Answer: 4.21×10⁻⁸
Explanation:
1) Assume a general equation for the ionization of the weak acid:
Let HA be the weak acid, then the ionization equation is:
HA ⇄ H⁺ + A⁻
2) Then, the expression for the ionization constant is:
Ka = [H⁺][A⁻] / [HA]
There, [H⁺] = [A⁻], and [HA] = 0.150 M (data given)
3) So, you need to determine [H⁺] which you do from the pH.
By definition, pH = - log [H⁺]
And from the data given pH = 4.1
⇒ 4.10 = - log [H⁺] ⇒ [H⁺] = antilog (- 4.10) = 7.94×10⁻⁵
4) Now you have all the values to calculate the expression for Ka:
ka = 7.94×10⁻⁵ × 7.94×10⁻⁵ / 0.150 = 4.21×10⁻⁸
