14.Explain differences

Question 1

What is the difference between a physical and chemical change?(example)

Answer 1

In a physical change the substance does not change its composition and in a chemical change it does change its composition.
Physical:melting
Chemical:burning paper

Question 2

What is the difference between an element and a compound(examples)

Answer 2

An element is a pure substance made up of only one type of atom and a compound is a pure substance made up of more than 1 type of atom.
Element:oxygen
Compound:water

Question 3

What is the difference between an open and a closed system and why it is necessary to balance chemical equation

Answer 3

In an open system, substances exchange matter with its surroundings, so the amount of matter in the system may change. In a closed system, substances can’t exchange matter with its surroundings, so the amount of matter in the system remains constant.
Closed: closed chimney
Open:burn paper outside