A physical change is one that doesn’t change the internal structure ofmatter, example:
* When we break a paper in two parts, one maybe will be bigger and the other smaller but it’s still paper
* When we take a plasticine and westill plasticine part it in the middle and we make this again and again we have very little pieces, but is still plasticine
* The states of the water that are,liquid, solid and gas but it’s still H2O
11. - Describe the results of a chemical change. List four indications of chemical change
Chemical changes are processes thatchange the nature of the matter and sometimes create new, the four indicators of chemical change are:
1. Formation of heat
2. Formation of precipitate3. Bubbles
4. Change of color
12. - Solve each of the following.
a) In the complete reaction of 22.99g of sodium with 35.45g of chlorine, what mass ofsodium chloride is formed? 58.44g
b) A 12.2-g sample of X reacts with a sample Y to form 78.9g of XY. What is the mass of Y reacted? 91.1g
13. Thinking critically. Afriend tells you, “Because composition does not change during physical change, the appearance of a substance does not change.” Is your friend correct? Why?
Nobecause a physical change is something that we can see
14. Classifying Classify each of the following examples as physical change or a chemical change.
a) Crushing analuminum can: PHYSICAL
b) Recycling used aluminum cans to make new aluminum cans: PHYSICAL
c) Aluminum combing with oxygen to form aluminum oxide: CHEMICAL