CONCEPT 2 UNIT 2

Question 1

melting point

Answer 1

the specific temperature at which a solid substance changes into a liquid

Question 2

boiling point

Answer 2

at which the point a liqud substance bubbles

Question 3

viscosity

Answer 3

the state of being thick, sticky, and semifluid in consistency, due to internal friction.

Question 4

solubility

Answer 4

Solubility is the ability of a substance to dissolve in a solvent to form a homogeneous solution.

Question 5

solute

Answer 5

A solute is the substance that is dissolved in a solvent to form a solution.

Question 6

solvent

Answer 6

A solvent is the substance in which a solute dissolves to form a solution.

Question 7

solution

Answer 7

A solution is a homogeneous mixture formed when a solute dissolves in a solvent.

Question 8

density

Answer 8

Density is the amount of mass in a given volume of a substance, usually expressed as mass per unit volume (e.g., grams per cubic centimeter).

Question 9

combustibility

Answer 9

Combustibility is the ability of a substance to catch fire and burn in the presence of oxygen.

Question 10

reactivity

Answer 10

Reactivity is the ability of a substance to undergo a chemical change or reaction with other substances.

Question 11

oxidation

Answer 11

Oxidation is a chemical reaction in which a substance loses electrons, often involving the addition of oxygen or the removal of hydrogen.

Question 12

chemical reaction

Answer 12

A chemical reaction is a process in which substances (reactants) change into new substances (products) with different properties.

Question 13

law of conservation of matter

Answer 13

The law of conservation of matter states that matter cannot be created or destroyed in a chemical reaction; it only changes forms.

Question 14

explain the difference between physical properties and chemical properties and list the examples of each

Answer 14

Physical properties are characteristics of a substance that can be observed or measured without changing its chemical identity.
Chemical properties describe a substance’s ability to undergo a chemical change or reaction, resulting in a new substance.

Examples:

Physical properties:

Color

Density

Melting point

Boiling point

Solubility

Hardness

Chemical properties:

Combustibility (ability to catch fire)

Reactivity with acids

Oxidation (rusting)

Toxicity

Ability to ferment

Want me to explain any of these examples more?

Question 15

explain the difference between physical changes and chemical changes

Answer 15

Physical changes are changes that affect the form or appearance of a substance but don’t change its chemical composition. The substance remains the same at the molecular level.

Chemical changes result in the formation of one or more new substances with different chemical properties and compositions.

Key difference:

• Physical change = no new substance formed
• Chemical change = new substance(s) formed

Examples:

• Physical change: melting ice, tearing paper, dissolving sugar in water
• Chemical change: burning wood, rusting iron, baking a cake

Want me to dive into signs that help identify each type of change?

Question 16

a piece of metal in 4 cm by 10 cm by 2 cm find its mass if it has a density of 2 g/cm2

Answer 16

1. Find the volume of the metal piece:
   Volume = length × width × height
   = 4 cm × 10 cm × 2 cm
   = 80 cm³
2. Given density = 2 g/cm³ (I think you meant g/cm³, since density is usually in g/cm³, not g/cm²)
3. Calculate mass using the formula:
   Mass = Density × Volume
   = 2 g/cm³ × 80 cm³
   = 160 g

Question 17

a piece of plastic with Mass of 15g is placed in a graduated cylinder the water level in the graduated cylinder rises from 30 ml to 55ml when when the plastic is added find the the density of plastic

Answer 17

1. Find the volume of the plastic by the water displacement method:
   Volume of plastic = Final water level - Initial water level
   = 55 ml - 30 ml
   = 25 mlSince 1 ml = 1 cm³, volume = 25 cm³.
2. Given mass of plastic = 15 g
3. Calculate density using the formula:
   Density = Mass / Volume
   = 15 g / 25 cm³
   = 0.6 g/cm³

Question 18

classify the flowing changes in physical or chemical

boling
crfumpling
burning
freezing
eveperating
rotting
rusting
sawing
crushoing

Answer 18

Physical changes:

• Boiling
• Crumpling
• Freezing
• Evaporating
• Sawing
• Crushing

Chemical changes:

• Burning
• Rotting
• Rusting

Question 19

list the device that a chemical change and thus a chemical reaction has occurred

Answer 19

1. Color change (without mixing)
2. Formation of a gas (bubbles or fizzing)
3. Formation of a precipitate (a solid appears in a liquid)
4. Change in temperature (gets hotter or colder without external heating/cooling)
5. Emission of light or sound
6. Irreversibility (change cannot easily be undone)