VLab Prec Reactions Directions

advertisement

VLab: Precipitation Reactions: Data & Observations

All questions are to be answered on your own paper . Related tables, charts, and diagrams can be completed on the Data Sheet (PDF) provided by your teacher.

There are thirty-five combinations of aqueous solutions for you to investigate. (Note Table 1 on the Data

Sheet.) Some of these combinations will produce precipitates ; others will not.

Step-by-step instructions for experimenting with the first combination (AgNO

3

and NaCl) are listed below.

A.

For the first solution, select AgNO

3

.

B.

For the second solution, select NaCl.

C.

The Erlenmeyer flasks that appear are filled with the two aqueous solutions.

1.

Note the color of each solution. This information has already been recorded for you in Table 1.

2.

If a reaction were to occur between these two aqueous solutions, what would the products be?

(Given your knowledge of exchange reactions, you should expect the products to be NaNO

3

and AgCl.)

D.

Begin building the chemical equation by dragging a sodium ion to the first product box and a nitrate ion to the second product box. Place your cursor over each ion to display its charge. Since these ions have equal but opposite charges (+1 and -1), you do not need to drag any additional ions to this area. NaNO

3

is a valid chemical formula.

E.

Finish building the chemical equation by dragging a silver ion and a chloride ion to the third and fourth product boxes, respectively. These two ions also have equal but opposite charges (+1 and -1), so you have produced another valid chemical formula.

F.

Balance the chemical equation by selecting any needed coefficients. For this example, the equation is already balanced. (The simulation recognizes blanks as coefficients of

"1.")

G.

Select the Check button to check your work. If your product(s) had been incorrect, the product box(es) would have turned red. Likewise, any incorrect coefficients would have

H.

turned red.

Now, select the React button to see what actually happens when aqueous solutions of

AgNO

3

AgNO

3

and NaCl are combined. It turns out that combining aqueous solutions of

and NaCl does produce a precipitate.

3.

In the first block of Table 1, note the color of this precipitate.

I.

Notice the chemical equation at the end of the video. Since a precipitate forms, the product ions for the insoluble compound are shown as a molecule (rather than separate ions). Thus, you can see that the precipitate for this reaction is AgCl.

4.

In the first block of Table 1, record the formula for this precipitate.

5.

Write the complete balanced equation for this reaction (on your own paper).

Indicate the state of each compound (aqueous or solid).

Continue experimenting with the remaining solution combinations. For each:

J.

Note the color of each solution.

6.

Record these colors in Table 1.

K.

Build and balance the chemical equation for the predicted reaction.

L.

Click the Check button to check your work. Make corrections as needed and click the

Check button again.

M.

Once you have built the correct chemical equation, select the React button.

7.

Record your observations in Table 1. If a precipitate forms, indicate its color and formula. If no visible reaction occurs, write "NVR."

8.

When a combination yields a precipitate, write the complete balanced equation.

Label each compound as aqueous or solid.

Download