4B3 Predicting Products

Question 1

List five types of chemical reactions.

Answer 1

1. Combination
2. Decomposition
3. Single-Replacement
4. Double-Replacement
5. Combustion

These reaction types describe how reactants transform into products through rearrangement or energy changes.

Question 2

True or False:

Combustion always produces water and carbon dioxide.

Answer 2

True

Combustion reactions involve a hydrocarbon reacting with oxygen to yield carbon dioxide, water and energy.

These products are consistent regardless of the specific hydrocarbon used in the reaction.

Question 3

Which gas is produced during incomplete combustion?

Answer 3

Carbon monoxide

Incomplete combustion produces less energy and creates carbon monoxide instead of carbon dioxide.

Question 4

How can you extinguish a small fire without a fire extinguisher?

Answer 4

By smothering it with a heavy cloth or blanket to cut off the oxygen supply.

Oxygen is essential for combustion; removing it extinguishes the fire.

Question 5

Which steps are followed to balance a combustion equation?

Answer 5

1. Write the skeleton equation.
2. Balance carbon.
3. Balance hydrogen.
4. Balance oxygen.

A final check ensures the number of atoms on both sides of the equation is equal.

Question 6

How is a decomposition reaction different from a combination reaction?

Answer 6

• Decomposition: It breaks down a single reactant into multiple products.
• Combination: It forms a single product from multiple reactants.

Decomposition is essentially the reverse of a combination reaction.

A combination reaction is also known as a synthesis reaction. Decomposition reactants always start with a single reactant.

Question 7

List three indicators of a chemical change.

Answer 7

1. Heat or light emission.
2. Color change.
3. Gas formation (bubbling).

These are observable signs that a chemical reaction has occurred.

Question 8

What does the state symbol (aq) represent in a chemical reaction?

Answer 8

Aqueous, meaning the substance is dissolved in water.

State symbols (g, l, s, aq) indicate the physical state of substances in a chemical reaction.

Question 9

True or False:

All synthesis reactions produce binary compounds.

Answer 9

False

Synthesis reactions can produce binary or ternary compounds depending on the reactants involved.

Question 10

How does a metal carbonate decompose?

Answer 10

It breaks down into:

1. A metal oxide
2. Carbon dioxide gas (CO₂)

Example: CaCO₃→CaO+CO₂

Question 11

List the products of the decomposition of potassium chlorate (KClO₃).

Answer 11

1. Potassium chloride (KCl)
2. Oxygen (O₂)

The decomposition of metal chlorates produces a metal chloride and oxygen.
Reaction: 2KClO₃→2KCl+3O₂

Question 12

List the products of the decomposition of calcium hydroxide (CaOH₂).

Answer 12

1. Calcium oxide (CaO)
2. Water (H₂O)

Reaction: Ca(OH)₂→CaO+H₂O

Question 13

Fill in the blank:

Carbon dioxide (CO₂) and water (H₂O) combine to form _______ ____ ?

Answer 13

Carbonic acid

(H₂CO₃)

This is an example of a synthesis reaction forming a ternary compound.

A ternary compound is a compound made up of three elements.

Question 14

True or False:

Energy is usually required for decomposition reactions.

Answer 14

True

Energy input, such as heat, light, or electricity, is often necessary to break bonds in decomposition reactions.

Question 15

How can you predict the product of a synthesis reaction?

Answer 15

By analyzing the reactants and their properties.

For example, combining a metal and a nonmetal typically forms an ionic compound.

Question 16

True or False:

A complex compound can decompose into its individual elements.

Answer 16

False

A complex compound usually breaks into smaller compounds, not individual elements.

Example: ABC→AB+BC

Question 17

What is a dehydration reaction?

Answer 17

A unimolecular reaction where the reactant loses two hydrogen atoms and an oxygen atom, forming water and a dehydrated version of the reactant.

Dehydration reactions involve one reactant and typically result in the formation of a double bond in organic compounds.

Question 18

Fill in the blank:

In a dehydration reaction, one product is always ______.

Answer 18

water

The formation of water from two hydrogen atoms and one oxygen atom lost from the reactant is a hallmark of dehydration reactions.

Question 19

Define:

hydrolysis

Answer 19

A chemical reaction where a water molecule is used to break bonds in a reactant, typically producing two products.

Hydrolysis means “to cut with water”.

Water acts as a reactant, providing a hydroxyl group and a hydrogen atom to break bonds in the reactant.

Question 20

How does a dehydration reaction differ from hydrolysis?

Answer 20

• Dehydration: It produces water as a product.
• Hydrolysis: It uses water as a reactant to break bonds.

Dehydration typically results in two products, while hydrolysis often splits a molecule into two smaller ones.

Question 21

List two products of the dehydration of ethanol.

Answer 21

1. Ethylene
2. Water

Ethanol loses a hydrogen and a hydroxyl group during dehydration to form ethylene and water.

Question 22

Which compound is the dehydrated product of copper(II) sulfate pentahydrate (CuSO₄·5H₂O)?

Answer 22

Copper(II) sulfate (CuSO₄)

Heating copper(II) sulfate pentahydrate (CuSO₄·5H₂O) removes water molecules to form anhydrous CuSO₄.

The color change from blue (hydrated) to white (anhydrous) is a visible indicator of this reaction.

Question 23

Define:

condensation reaction

Answer 23

A chemical reaction in which water is lost from one or more reactants.

Condensation reactions can involve multiple reactants, unlike unimolecular dehydration reactions.

Dehydration reactions are a subset of condensation reactions.

Question 24

What are the reactants and products in the hydrolysis of sucrose?

Answer 24

• Reactants: Sucrose and water.
• Products: Glucose and fructose.

Hydrolysis breaks sucrose into its monomers by using a water molecule.

Question 25

# Fill in the blank: Inorganic dehydration reactions often result in the **removal of water from** \_\_\_\_\_\_\_\_.

Answer 25

hydrates ## Footnote Hydrates lose water to form anhydrous compounds, a process often driven by heat.

Question 26

# Define: neutralization reaction

Answer 26

A reaction where **acids and bases react** to form salt and water. ## Footnote Neutralization involves the reaction of acids donating protons and bases accepting them. Hydrogen ions (H⁺) and hydroxyl ions (OH⁻) combine to form water.

Question 27

What is the **general equation** for a neutralization reaction?

Answer 27

Acid + Base → Salt + Water ## Footnote Neutralization is a form of displacement reaction. Displacement reactions rearrange ions to form new compounds.

Question 28

Which **acid** reacts with NaOH to form NaCl?

Answer 28

Hydrochloric acid | (HCl) ## Footnote Reaction: HCl + NaOH → NaCl + H₂O

Question 29

# Define: pH

Answer 29

A scale **measuring the acidity or basicity** of a solution. ## Footnote pH ranges from 0 (acidic) to 14 (basic); pH = 7 is neutral.

Question 30

How does the **pH change** when a strong acid reacts with a strong base?

Answer 30

It becomes **neutral** (pH = 7). ## Footnote This reaction completely neutralizes the acid and base.

Question 31

Which **type of solution** is produced when a weak acid reacts with a strong base?

Answer 31

A **basic** solution (pH > 7). ## Footnote The strong base dominates the reaction, making the solution basic.

Question 32

List *two* **strong acids** and *two* **strong bases**.

Answer 32

* Strong **Acids**: HCl, H₂SO₄ * Strong **Bases**: NaOH, KOH ## Footnote Strong acids/bases dissociate completely in water forming ions. Weak acids/bases dissociate partially in water due to their strong attachment to protons.

Question 33

# Fill in the blank: **Bee stings are** \_\_\_\_\_\_\_ and can be treated with baking soda.

Answer 33

acidic ## Footnote Baking soda, a base, neutralizes the acid in bee stings.

Question 34

What happens when **HBr reacts with KOH**?

Answer 34

Water (**H₂O**) and potassium bromide (**KBr**) **are formed**. ## Footnote Reaction: HBr + KOH → KBr + H₂O

Question 35

# Fill in the blank: Toothpaste contains \_\_\_\_\_\_ compounds to **neutralize acidic mouth bacteria**.

Answer 35

basic ## Footnote Basic compounds in toothpaste help maintain oral pH balance.

Question 36

What is **titration** used for in chemistry?

Answer 36

To determine the **concentration of a compound**. ## Footnote An example would be an acid-base titration, which uses a known acid or base to neutralize the unknown solution.

Question 37

# Define: precipitation reaction

Answer 37

A reaction where two soluble salts react to **form an insoluble product**. ## Footnote These reactions involve the exchange of ions between compounds in aqueous solutions. Precipitation is a type of a double-displacement reaction.

Question 38

When do **precipitates form** in chemical reactions?

Answer 38

When the product of a reaction between cations and anions is **insoluble in water**. ## Footnote Solubility rules help predict the formation of a precipitate.

Question 39

# True or False: All silver salts **are soluble**.

Answer 39

False ## Footnote Most silver salts are insoluble, with exceptions like silver nitrate (AgNO₃​) and silver acetate (AgC₂H₃O₂​).

Question 40

What is the purpose of a **molecular equation**?

Answer 40

It **represents the full chemical reaction**, showing all reactants and products as compounds. ## Footnote It does not separate compounds into their ionic forms.

Question 41

# Define: spectator ions

Answer 41

**Ions that remain unchanged** on both sides of a chemical reaction and do not participate in forming the product. ## Footnote They are removed when writing the net ionic equation.

Question 42

List the *five* steps to **write a net ionic equation**.

Answer 42

1. Write the balanced molecular equation. 1. Identify substances that ionize. 1. Write the complete ionic equation. 1. Cancel spectator ions. 1. Write the net ionic equation. ## Footnote These steps help isolate the chemical species involved in forming the precipitate. The net ionic equation represents chemical species directly involved in the reaction, excluding spectator ions.

Question 43

List the *three* types of **precipitation reactions**.

Answer 43

1. Precipitation in a solution. 1. Precipitation in agar gel. 1. Precipitation in agar gel with an electric field. ## Footnote These methods differ based on the medium in which precipitation occurs.

Question 44

# True or False: Group I element salts are **generally insoluble**.

Answer 44

False ## Footnote Salts of Group I elements are generally soluble in water.

Question 45

# True or False: Hydroxide salts of Group II elements are **highly soluble**.

Answer 45

False ## Footnote Hydroxide salts of Group II elements are only slightly soluble.

Question 46

# Which ions are usually **insoluble**: carbonate or nitrate

Answer 46

Carbonate ## Footnote Most carbonates are insoluble, while nitrates are generally soluble.

Question 47

# Define: displacement reaction

Answer 47

A reaction where **one element replaces another** in a compound. ## Footnote The replaced element must have similar chemical properties to the replacing element.

Question 48

What does a **double displacement** reaction involve?

Answer 48

**Two compounds reacting** to form two new compounds. ## Footnote Double displacement reactions differ from single displacement by involving no uncombined element.

Question 49

What is an example of a **double-replacement** reaction?

Answer 49

Reaction of **NaCl(aq) and AgNO₃(aq)** to form AgCl(s) and NaNO₃(aq). ## Footnote Double-replacement reactions involve swapping cations or anions between two ionic compounds.

Question 50

# Define: single displacement reaction

Answer 50

A + BC → AC + B ## Footnote A unbonded element replaces an ion in a compound. A is an unbonded element that replaces ion B in the compound BC.

Question 51

What is the **activity series** of metals?

Answer 51

A ranking of metals **based on their relative reactivity**; It provides a qualitative comparison of the reactivities of elements. ## Footnote Metals higher in the series are more reactive and can displace metals lower in the series. Alkali and alkaline earth metals rank high in the activity series.

Question 52

# True or False: Potassium is **more reactive** than magnesium.

Answer 52

True ## Footnote Potassium is ranked higher than magnesium in the activity series of metals.

Question 53

How can you **determine if a reaction will occur** using the activity series?

Answer 53

Compare the **positions of the metals in the reactants** on the activity series. ## Footnote If the uncombined metal is higher than the compound’s metal, a reaction occurs.

Question 54

Which **non-metal is the most reactive** according to the activity series?

Answer 54

Fluorine ## Footnote Fluorine is the most reactive non-metal, replacing less reactive non-metals like iodine.

Question 55

How does **atom size** affect reactivity in the activity series?

Answer 55

**Larger atoms** with fewer valence electrons are generally **more reactive**. ## Footnote Reactivity increases with easier electron donation or acceptance.

Question 56

How is an electrochemical chart **different from an activity series**?

Answer 56

It provides **numerical values for reactions**. ## Footnote The activity series offers a qualitative comparison of reactivities.