Prepare 2 test tubes with approximately 5 ml of dilute Cu(II) chloride solution in each
Prepare 1 test tube with 5 ml sodium carbonate solution
Prepare 1 test tube with 5 ml sodium sulphate solution
Carefully pour the sodium carbonate solution into one of the test tubes containing copper(II) chloride and observe what happens
Carefully pour the sodium sulphate solution into the second test tube containing copper(II) chloride and observe what happens
Results:
A light blue precipitate forms when sodium carbonate reacts with copper(II) chloride
No precipitate forms when sodium sulphate reacts with copper(II) chloride
It is important to understand what happened in the previous demonstration. We will look at what happens in each reaction, step by step.
Reaction 1: Sodium carbonate reacts with copper(II) chloride.
When these compounds react, a number of ions are present in solution: Cu
2+ , Cl
, Na
+ and CO
32
.
Because there are lots of ions in solution, they will collide with each other and may recombine in different ways. The product that forms may be insoluble, in which case a precipitate will form, or the product will be soluble, in which case the ions will go back into solution. Let's see how the ions in this example could have combined with each other:
Cu
2+ + CO
32
CuCO
3 Cu
2+ + 2Cl
CuCl
2 Na
+ + Cl
NaCl
Na
+ + CO
32
Na
2 CO
3 You can automatically exclude the reactions where sodium carbonate and copper(II) chloride are the products because these were the initial reactants. You also know that sodium chloride (NaCl) is soluble in water, so the remaining product (copper carbonate) must be the one that is insoluble. It is also possible to look up which salts are soluble and which are insoluble. If you do this, you will find that most carbonates are insoluble, therefore the precipitate that forms in this reaction must be CuCO
. The reaction that has taken place between the ions in solution is as follows:
2Na
+ + CO
32
+ Cu
2+ + 2Cl
CuCO
3 + 2Na
+ + 2Cl
Reaction 2: Sodium sulphate reacts with copper(II) chloride.
The ions that are present in solution are Cu
2+ , Cl
, Na
+ and SO
4 .
The ions collide with each other and may recombine in different ways. The possible combinations of the ions are as follows:
Cu
2+ + SO
42
CuSO
4 Cu
2+ + 2Cl
CuCl
2 Na
+ + Cl
NaCl
Na
+ + SO
42
Na
2 SO
4 If we look up which of these salts are soluble and which are insoluble, we see that most chlorides and most sulphates are soluble. This is why no precipitate forms in this second reaction. Even when the ions recombine, they immediately separate and go back into solution. The reaction that has taken place between the ions in solution is as follows:
2Na
+ + SO
42
+ Cu
2+ + 2Cl
2Na
+ + SO
42
+ Cu
2+ + 2Cl
Questions & Answers
why economics is difficult for 2nd school students.
economics theory describes individual behavior as the result of a process of optimization under constraints the objective to be reached being determined by
Kalkidan
Economics is a branch of social science that deal with How to wise use of resource ,s
Kassie
need
WARKISA
Economic Needs: In economics, needs are goods or services that are necessary for maintaining a certain standard of living. This includes things like healthcare, education, and transportation.
Money market is a branch or segment of financial market where short-term debt instruments are traded upon. The instruments in this market includes Treasury bills, Bonds, Commercial Papers, Call money among other.