Chemical Changes Guided Lab

​On the back of your paper, jot down notes and drawings that will help you remember the meaning of these words from the

reading.

1. chemistry

2. physical change

3. state of matter

4. chemical change

5. chemical bonds

​Random student callout!

Explain what a chemical reaction is.

Step 1: Fill the graduated cylinder up with

20ml of water.

Step 2: Take ONE effervescence tablet and

break it up so that it will fit into the

graduated cylinder.

​

​Mini experiment

You just experienced a chemical change (chemical reaction). A chemical change happens when atoms are rearranged to create a new substance.

The bubbles, or production of a gas, happens when baking soda (sodium bicarbonate) and citric acid from the tablet react chemically in water.

They create sodium citrate, water, and carbon dioxide gas, which causes bubbles. As you can see new substances were formed.

Observation!

Write your observations about what happens to the matchstick.

Burning or explosions are also evidence that a chemical change has taken place.

The phosphorus and sulfur on the tip of the match are burned up during the chemical reaction and create light and heat energy.

There are 3 other pieces of evidence that prove a chemical

change or chemical reaction has taken place.

The 3rd example is called a precipitate. When two liquid are

combined together, but a solid is produced that solid is called a precipitate.

The 4th piece of evidence is an unexpected temperature change.


Often heat is released (exothermic) when elements or compounds are combined. This causes the temperature to rise.

Sometimes heat is absorbed (endothermic) when elements or compounds are combined. This causes the temperature to fall.

These changes in temperature prove a chemical reaction occurred.

Lastly, sometimes an unexpected color change occurs when two chemicals are combined. This is evidence of a chemical change.

Rust is one example of an unexpected chemical

change.