Formulae and Equations Chemical formulae and equations are used by scientists to explain what happens during chemical reactions.
Chemical equations show the bonds that are broken and formed when atoms are rearranged during a chemical reaction. They tell the scientist what chemicals are involved in a reaction and the products that have been formed. They also tell the scientist how much of each reactant is needed in the reaction and how much product will be formed.
There are two types of equation: z z
Word equations. For example: Hydrochloric acid + sodium hydroxide → sodium chloride + water
zz Chemical equations. For example: HCl + NaOH → NaCl + H2O
Use what you have learned about formulae and equations in this chapter to complete the following tasks.
Identifying the parts of a chemical equation Mg + O2 2 MgO
1 Label the chemical equation above using the following labels: zz
Product zz Reactants zz Subscript
Linking subscripts and coefficients 2 In boxes a–e below i. Circle each subscript in the chemical formula.
ii. Draw a square around each coefficient. iii. Answer the questions related to each chemical formula.
a. O2
What does the O represent?
d. Na = 254 2Na2SO4
How many atoms of each element are there?
S = O = b. C = CO2
How many atoms of each element are there?
O = e.
C = c. 5H2
How many atoms of hydrogen are there?
2C2H6
How many atoms of each element are in the formula shown?
