Question

Why is it better to write a net ionic equation for this reaction (justify):
Ca(OH)2(aq) + Na2SO4 --> ?

Answer 1

@JoannaBlackwelder

Answer 2

That depends on what you are writing the reaction for. Is there any more context to this problem?

Answer 3

"conditions around a hydrothermal vents deep in the ocean floor can enable chemical reactions that produce solid materials. A student models one of these reactions by combining aqueous Ca(OH)2 and Na2SO4, and observes the formation of a solid in a liquid.

Justify the choice of a net ionic equation for describing this reaction and write the balanced net ionic equation."

Answer 4

@JoannaBlackwelder

Answer 5

A reaction of aqueous solutions to produce a solid and a liquid sounds like a precipitation reaction to me.

Answer 6

The net ionic reaction shows how the precipitate is formed and everything else just stays as ions in solution.

Answer 7

Net reactions are always useful for precipitation reactions. Make sense?

Answer 8

yeah... how do I make a net ionic equation for this? @JoannaBlackwelder

Answer 9

First, do double replacement.

Answer 10

Then check your products to determine which one is the precipitate and which one stays in solution using a solubility table.

Answer 11

Ca(OH)2(aq) + Na2SO4 --> CaSO4 + 2NaOH

Answer 12

Yup

Answer 13

the precipitate is CaSO4

Answer 14

Good. :)

Answer 15

what now?

Answer 16

Now we need to write the reactants and products as they would be in solution, as ions (for everything except the precipitate).

Answer 17

So, Ca(OH)2 would be Ca2+ + 2OH-, for example.

Answer 18

huh?

Answer 19

Ca(OH)2 written as ions is \[Ca ^{2+}+2OH ^{-}\]

Answer 20

This is how the compound exists in solution (aqueous)

Answer 21

oh ok yeah

Answer 22

Can you write out the other aqueous compounds as ions?

Answer 23

Na2SO4 --> Na1+ + 4SO
2NaOH --> 2Na+ + 2OH-
?

Answer 24

NaOH looks good! :)

Answer 25

Look at Na2SO4 again.

Answer 26

hmmm... not really sure how to do this

Answer 27

\[Na _{2}SO _{4}\rightarrow2Na ^{+}+SO _{4}^{2-}\]

Answer 28

Make sense?

Answer 29

why is na only + and so is 2-?

Answer 30

Na has 1 valence electron, and it loses that electron to make an ion, making it +1

Answer 31

oh ok

Answer 32

SO4 is a polyatomic ion that has a charge of 2-

Answer 33

got it got it

Answer 34

:)

Answer 35

So, can you write the whole reaction with the aqueous compounds as ions?

Answer 36

Ca(OH)2(aq) + Na2SO4 --> 2Na+ + SO2− + 2Na+ + 2OH-

Answer 37

\[Ca ^{2+}+2OH ^{-}+2Na ^{+}+SO _{4}^{2-}rightarrowCaSO _{4}+ 2Na ^{+}+2OH ^{-}\]

Answer 38

Make sense?

Answer 39

OHHHHHHH that makes a lot more sense

Answer 40

:)

Answer 41

Now cancel out anything that is on both sides.

Answer 42

is that my net ionic equation though?

Answer 43

No, that is the total ionic compound.

Answer 44

Ca2+ + SO2 --> CaSO4 ?

Answer 45

Except for perfect!