Determining Chemical Activity. Concept :. A chemical reaction is said to occur when changes are observed, such as:. 1. When a given mass of substance disappears 2. There is a release of gas 3. There is a formation of precipitate 4. There is a change in colour
A chemical reaction is said to occur when changes are observed, such as:
1. When a given mass of substance disappears
2. There is a release of gas
3. There is a formation of precipitate
4. There is a change in colour
5. There is a change in mass
6. There is a change in temperature
The reactivity of metal is related to its ability to lose electron (i.e to be oxidized). It is possible to arrange nearly all the metals (even non-metals) with a single series in order of their reactivities. This series, known as the activity or electromotive series indicates which elements are capable of replacing other elements from their compounds.
In the list, the metals are arranged in such a way that the most active metals head the list, and the least active metal comes at the last. Hydrogen, a non-metal is included because the reactions involving metals and acids are common and important.
Test tube rack
1. Place 3mL of CuSO4 solution in a test tube. Take note of its color.
2. Add 1mL of NH4OH solution to the CuSO4 solution. Observe and record what happens.
1. Place 5mL HCl in each of four test tubes.
2. Add the metals separately to the test tubes. Label each test tube.
3. observe what happens in each tube. Record any change in color or appearance of the metal pieces. Record observations on the data chart.
1. Place 3mL of ZnSO4 in a test tube. Add 1mL of BaCl2 to it. Describe and Record what happens.
CuSO4 + 2NH4OH (NH4)2SO4 + Cu(OH)2
(blue (colorless (dark blue
Solution) Solution) solution)
B. A more reactive element replaces a less active element from its compound.
2HCl + Fe FeCl2 + H2
2HCl + Mg MgCl2 + H2
6HCl + 2Al 2AlCl3 + H2
ZnSO4 + BaCl2 ZnCl2 + BaSO4
What observed change indicates chemical reactivity in A?
There’s a change in color.
Which of the substance used in B showed changes?
Fe - iron
A reaction occurs when a more active element replaces a less active element in the solution. Which element was most active in B? Which was the least active?
Mg- Most active
Cu – Least active
Chemical and Physical Change
What other pieces of evidence will show occurrence of chemical reactions?
The rusting of metals,
Here are some examples of chemical reactions you may have seen before:
Rusty Nails: A chemical reaction between the iron in steel and oxygen in the atmosphere causes rust.
Photographic film: There is a chemical reaction on the film wherever light hits it.
Batteries: Chemical reactions within batteries produce electrons called electrochemical reactions.
Halloween Lightsticks: A chemical reaction excites atoms causing the stick to glow.
Homemade Volcano: When baking soda and vinegar are combined, they erupt as carbon dioxide gas is released. (If you try this, be prepared to clean up afterward!)
Fizz Fizz: Dropping an Alka-Seltzer tablet in water makes a bubbling chemical reaction.
An Old Fruit Salad: Cut a piece of fruit open and it soon turns brown, reacting to the oxygen in the air.
Rusting of Nails
Group 6 1-AAPD1I