Science 10 - Balancing Chemical Equations

Comprehensive practice flashcards covering chemical reaction definitions, equation types, the Law of Conservation of Mass, balancing rules, common covalent formulas, and practice balancing problems.

what is a chemical reaction?

• A change in the arrangement and interactions between atoms and ions -

• occurs when a substance combines with another to form a new substance

three indications of a chemical reaction?

• Bubbling,

• production of light

• heat

• new colours

three ways to show chemical reactions equations?

• Word equations

• skeleton equations

• balanced chemical equations.

What is a word equation?

• An equation that uses words or names to show the reaction

• for example: methane + oxygen -> water + carbon dioxide

What is a skeleton equation?

• An equation that uses chemical symbols and formulas to show the reaction

• without balancing the quantities of atoms

• (for example: $CH_4 + O_2 \rightarrow H_2O + CO_2$).

In a chemical equation, where are the reactants and products located?

• Reactants are found on the left side

• products are found on the right side

What is the Law of Conservation of Mass in the context of chemical reactions?

• Matter cannot be created or destroyed, -

• the mass of the reactants must equal the mass of the products

• the number of each type of atom must be the same on both sides.

What is a coefficient in a chemical equation?

• A number placed in front of atoms or compounds

• indicates how many of each atom or compound are present.

What are the chemical formulas for the common covalent molecules methane, glucose, ethane, and ammonia?

• Methane is $CH_4$,

• glucose is $C_6H_{12}O_6$,

• ethane is $C_2H_6$

• ammonia is $NH_3$.

According to the tips for balancing equations, what can be added, and what should NEVER be changed?

• Only add coefficients;

• NEVER change the subscript.

What atom types should generally be balanced first and last according to the balancing tips?

• Balance single atoms first (such as metals)

• balance oxygen and hydrogen last.

How should polyatomic ions (such as $SO_4^{2-}$) often be balanced?

• be balanced as a whole group if they appear intact on both sides of the reaction.

What is the balanced equation for the skeleton equation $K + O_2 \rightarrow K_2O$?

$$4K + O_2 \rightarrow 2K_2O$$

What is the balanced chemical equation for $CO_2 + H_2O \rightarrow C_6H_{12}O_6 + O_2$?

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$$

What is the balanced chemical equation for the word equation: iron + bromine -> iron (III) bromide?

$$2Fe + 3Br_2 \rightarrow 2FeBr_3$$

What is the balanced chemical equation for the word equation: zinc + lead (II) nitrate -> zinc nitrate + lead?

$$Zn + Pb(NO_3)_2 \rightarrow Zn(NO_3)_2 + Pb$$

What is the balanced chemical equation for the word equation: aluminum bromide + chlorine -> aluminum chloride + bromine?

$$2AlBr_3 + 3Cl_2 \rightarrow 2AlCl_3 + 3Br_2$$