number of ions per molecule?

Question

i have a question..
which compound contains the most number of ions per molecule
i) calcium chloride
ii) sodium oxide
iii) copper (II) bromide
iv) aluminum oxide

how to calculate it and some explanations about it also

Answer 1

First you need the formulas for the compounds; then you can see how many atoms (ions) make up 1 molecule of the compound:

i) CaCl2 [3 ions]
ii) Na2O [3 ions]
iii) CuBr2 [3 ions]
iv) Al2O3 [5 ions]

Answer 2

Calcium chloride - 3. 1 Calcium, 2 Chlorine
Sodium oxide - 3. 2 Sodium, 1 Oxygen
Copper (II) Bromide - 3. 1 Copper (II), 2 Bromine
Aluminum Oxide - 5. 2 Aluminum, 3 Oxygen

Good thing I saved my Chart of Common Ions from Science 9 :)

Anyways, you should have a chart of common ions like I do. If you don't, ask your teacher for one, and then ask your teacher why she thinks she's qualified to teach science.

Secondly, look at each of those compounds. They each have two parts. Calcium ||| Chloride. Sodium ||| Oxide. In this case, the parts on the rights are negative ions, while the ones on the left are positive. You must look at your chart and try to add up the Ions until they balance on both sides.

For example, Aluminum has a charge of +3, while oxygen has a charge of -2. The lowest common multiple of these two numbers are 6. So you need 2 Aluminum ions (3+3=6) and 3 Oxygen (2+2+2=6)

Answer 3

To answer this question you need to look at the emperical formulas for each of the compounds listed, then you can determine the number of atoms make up each of these.

Calcium Chloride - CaCl2
Sodium Oxide - Na2O
Copper (II) bromide - CuBr2
Aluminum Oxide - Al2O3

Looking at these it is easy to see that all of them have three atoms that make them up except for aluminum oxide which has 5.

Answer 4

you have to see which ones dissociate in water-i think thats all of them- then count the number of ions e.g. CaCl2 dissociates into Ca^+2 and Cl2 -