Chemical Reactions Complete Revision Flashcards

Comprehensive practice flashcards covering chemical reaction types, evidence of change, conservation of mass, acid reactions, and chemical equations based on the Year 9 Chemistry Revision Worksheet.

What is the best definition of a chemical reaction?

A process in which atoms rearrange and new substances form.

What happens to chemical bonds during a reaction?

Some existing bonds break and new bonds form.

List four observations that provide evidence of a chemical reaction.

Any four of the following: colour change, gas bubbles, precipitate formation, light production, sound production, temperature change (heat given off or taken away), odour/smell, or reactants disappearing.

In the context of chemical equations, define a reactant.

A starting substance used in a reaction.

In the context of chemical equations, define a product.

A new substance made by a reaction.

What is the general layout for every chemical equation?

$$\text{reactants} \rightarrow \text{products}$$

State the Law of Conservation of Mass.

Mass is not created or destroyed in a chemical reaction; the total reactant mass equals the total product mass in a closed system.

If $12\,g$ of one reactant reacts completely with $6\,g$ of another, what is the total mass of the products?

$$18\,g$$

How can a reaction in an open beaker appear to lose mass without breaking the Law of Conservation of Mass?

A gaseous product may escape from the open beaker into the surroundings; the total mass including the escaped gas remains unchanged.

Define a combination reaction and its general pattern.

A reaction where two or more reactants join to form fewer products (usually one). General pattern: $A + B \rightarrow AB$

Define a decomposition reaction and its general pattern.

A reaction where one reactant splits into two or more products. General pattern: $AB \rightarrow A + B$

What are the products of an acid + base reaction (Neutralisation)?

$$\text{salt} + \text{water}$$

What are the products of an acid + metal reaction?

$$\text{salt} + \text{hydrogen}$$

What are the products of an acid + carbonate reaction?

$$\text{salt} + \text{water} + \text{carbon dioxide}$$

Describe the test for hydrogen gas and its positive result.

Place a lit match or burning splint at the test-tube opening. A positive result is a "squeaky pop."

Describe the test for carbon dioxide gas and its positive result.

Bubble the gas through a limewater solution. A positive result is the limewater turning cloudy or milky.

What specific ending is given to salts produced when hydrochloric acid ($HCl$) is used?

-chloride (e.g., sodium chloride)

Define dissociation in the context of an ionic compound.

The separation of an ionic compound into its individual ions in water.

What is a precipitate?

An insoluble solid product formed during a reaction between solutions.

Define oxidation in terms of oxygen.

The gain of or reaction with oxygen.

Define reduction in terms of oxygen.

The loss or removal of oxygen.

What is the difference between combustion and corrosion?

Combustion is a rapid redox reaction that produces heat and light; corrosion is a slow oxidation process that damages metal surfaces (like rusting).

What is a metal displacement reaction?

A reaction where a more reactive metal replaces a less reactive metal from its compound.

In the reaction $\text{iron} + \text{copper sulfate} \rightarrow \text{iron sulfate} + \text{copper}$, which metal is more reactive?

Iron (because it displaces the copper).

What do the state symbols (s), (l), (g), and (aq) stand for?

(s) = solid; (l) = liquid; (g) = gas; (aq) = aqueous (dissolved in water).

What is the balanced formula equation for the reaction of lead nitrate and potassium iodide?

$Pb(NO_3)_2(aq) + 2KI(aq) \rightarrow PbI_2(s) + 2KNO_3(aq)$"}],