An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?
Answer (2)
Lithium and bromine form an ionic compound with the empirical formula LiBr.
Oxygen and fluorine do not form an ionic compound.
Potassium and oxygen form an ionic compound with the empirical formula K 2 O .
Chlorine and potassium form an ionic compound with the empirical formula KCl.
The empirical formulas are: LiBr, not applicable, K 2 O , KCl.
b o x e d L i B r , n o t a ppl i c ab l e , K 2 O , K Cl
Explanation
Problem Analysis We are asked to determine whether given pairs of elements will form an ionic compound and, if so, to write the empirical formula of the compound formed. Ionic compounds are typically formed between a metal and a nonmetal. We need to identify the elements as metals or nonmetals and then determine the empirical formula based on the charges of the ions formed.
Lithium and Bromine Lithium (Li) is in Group 1 and forms a +1 ion ( L i + ). Bromine (Br) is in Group 17 and forms a -1 ion ( B r − ). Since lithium is a metal and bromine is a nonmetal, they will form an ionic compound. The charges balance, so the empirical formula is LiBr.
Oxygen and Fluorine Oxygen (O) is in Group 16 and forms a -2 ion ( O 2 − ). Fluorine (F) is in Group 17 and forms a -1 ion ( F − ). Since both oxygen and fluorine are nonmetals, they will not form an ionic compound.
Potassium and Oxygen Potassium (K) is in Group 1 and forms a +1 ion ( K + ). Oxygen (O) is in Group 16 and forms a -2 ion ( O 2 − ). Since potassium is a metal and oxygen is a nonmetal, they will form an ionic compound. To balance the charges, we need two potassium ions for each oxygen ion. The empirical formula is K 2 O .
Chlorine and Potassium Chlorine (Cl) is in Group 17 and forms a -1 ion ( C l − ). Potassium (K) is in Group 1 and forms a +1 ion ( K + ). Since potassium is a metal and chlorine is a nonmetal, they will form an ionic compound. The charges balance, so the empirical formula is KCl.
Final Answer In summary:
Lithium and bromine form LiBr.
Oxygen and fluorine do not form an ionic compound.
Potassium and oxygen form K 2 O .
Chlorine and potassium form KCl.
Examples
Ionic compounds are essential in various applications, such as table salt (NaCl) used for seasoning food, potassium iodide (KI) added to iodized salt to prevent iodine deficiency, and calcium chloride ( C a C l 2 ) used for de-icing roads in winter. Understanding how ionic compounds form helps us predict their properties and use them effectively in these and other applications. For example, knowing that sodium and chlorine form an ionic bond allows us to understand why table salt dissolves in water and conducts electricity when dissolved.
A current of 15.0 A flowing for 30 seconds results in a total charge of 450 Coulombs. This charge corresponds to approximately 2.81 × 1 0 21 electrons flowing through the electric device. Therefore, about 2.81 × 1 0 21 electrons pass through the device in the given time period.
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