Chemical Reactions Flashcards
What is a chemical reaction?
Two or more substances react chemically making a new product.
State the 4 signs of a chemical reaction.
colour change
gas produced
solid formed
energy (temperature) change
What is physical change?
when a substance changes without making a new product
Give three examples of chemical reactions.
frying an egg / making toast / candle burning / turkey cooking / burning wood in a fire / making steel from iron ore
Give three examples of physical changes.
melting ice / dissolving sugar / water boiling / water evaporating / freezing water
In a word equation, what name is given to the chemicals we start with?
reactants
In a word equation, what name is given to the new substances formed?
products
What should your word equation never include?
an equals sign ( = )
Write the following reaction as a word equation:
carbon burns in oxygen producing carbon dioxide
carbon + oxygen —> carbon dioxide
Write the following reaction as a word equation:
sodium chloride is formed when chlorine gas reacts with sodium
sodium + chlorine —> sodium chloride
Write the following reaction as a word equation:
magnesium burns in oxygen to produce magnesium oxide
magnesium + oxygen —> magnesium oxide
In the chemical formula:
4O2
What does the large 4 and small 2 indicate?
large 4: number of molecules
small 2: number of atoms
How many atoms are there in:
CH4
1 x C
4 x H
Total: 5 atoms
How many atoms are there in:
C2H6O
2 x C
6 x H
1 x O
Total: 9 atoms
How many atoms are there in:
Na2CO3
2 x Na
1 x C
3 x O
Total: 6 atoms
Element, compound or mixture?
compound
Element, compound or mixture?
element
Element, compound or mixture?
mixture
Explain how the following represents a mixture:
The ‘blue atoms’ (an elements) are not chemically joined to the molecules of the compound (red and light blue atoms).
This is a mixture of an element and a compound.
