Convert the following word equations into formula equations by changing element and compound names into chemical formulas.
1. sodium + oxygen ā sodium oxide
2. copper + silver nitrate ā copper(II) nitrate + silver
3. aluminum chlorate + barium sulfate ā aluminum sulfate + barium chlorate
4. bromine + calcium iodide ā calcium bromide + iodine
5. zinc sulfide + magnesium arsenate ā zinc arsenate + magnesium sulfide
6. cobalt + lead(II) nitrite ā cobalt(III) nitrite + lead
7. potassium + water ā potassium hydroxide + hydrogen
