Question

Write the molecular formula of the given compounds.

Answer 1

Answer:

(i) Al2(SO4)3

(ii) CaCl2

(iii) Fe(OH)2

(iv)AlPO4

(v) Fe(NO3)3

(vi) AuCl3

(vii) AgNO3

Explanation:

The numbers after the element/ion is a subscript meaning its put below the symbol

(i) Al has a charge of 3+ and SO4 has a charge of 2-

So to balance the charges 2 Al is needed to make the charge a 6+ and 3 SO4 is needed to make the charge a 6-. Once you can add the two charge values together to create 0, then you have the correct quantities

(ii) Same applies here, but Ca is 2+ and Cl is 1-, so 2 Cl- is needed to balance out the Ca

(iii) Ferrous is an ion of Iron with a 2+ charge, the other ion of Iron is Ferric which has a 3+ charge. OH has a charge of -1, so 2 OH is needed to balance out one Fe

(iv) Aluminum again has a charge of 3+ while PO4 has a charge of 3-, so they both balance out with one of each.

(v) Ferric is an ion of iron with a charge of 3+ and NO3 has a charge of 1-, so three of NO3 is needed to balance.

(vi) Gold has two charges, 1+ or 3+. However used in Gold chloride it is a 3+ and Cl is a 1-, so 3 of Cl is needed to balance one gold.

(vii) Silver has a charge of 1+ while NO3 has a charge of 1-, so they balance each other at one each.