Unit 5: Reactions

Question 1

Physical change

Answer 1

No new substance formed

Question 2

Chemical change

Answer 2

New substance formed

Question 3

Balancing equations

Answer 3

Need same number of atoms of each element in reactants and products

Question 4

What does a catalyst do?

Answer 4

Lowers activation energy and speeds up a reaction

Question 5

Combustion

Answer 5

CHO + O → CO + HO / CH + O → CO + HO

Question 6

Synthesis

Answer 6

Element + element → compound
Compound + compound → compound

Question 7

Decomposition

Answer 7

Compound → element + element
Compound → simpler compound + simpler compound

Question 8

Single replacement

Answer 8

Element (X) + compound (AB) → element (A) + compound (XB)

Question 9

Double replacement

Answer 9

Compound (XY) + compound (AB) → compound (XB) + compound (AY)

Question 10

Activity series

Answer 10

List of metals from most reactive to least

Question 11

Reactant

Answer 11

Element/compound added with another element/compound to create the product

Question 12

Product

Answer 12

Sum of the two or more elements/compounds

Question 13

Coefficient

Answer 13

Number before element/compound for balancing

Question 14

Endothermic

Answer 14

Positive energy charge

Question 15

Exothermic

Answer 15

Negative energy charge

Question 16

Precipitate

Answer 16

In an aqueous solution, the creation of a solid from a liquid substance