Mod 8

Question 1

What is the difference between solute and solvent?

Answer 1

Solute is in lesser quantity; solvent is in greater quantity.

Question 2

Define electrolyte and give examples of strong and weak electrolytes.

Answer 2

Electrolytes dissociate into ions in water. Strong electrolytes: NaCl, CaBr₂, HCl; Weak electrolytes: HF, NH₃.

Question 3

What is the definition of solubility?

Answer 3

Solubility is the amount of solute that can dissolve in a given amount of solvent at a specified temperature.

Question 4

True or False: Unsaturated solutions contain more solute than the solubility limit.

Answer 4

False.

Question 5

How does temperature affect the solubility of solids and gases?

Answer 5

Solids: solubility increases with temperature; Gases: solubility decreases with temperature.

Question 6

What are the three types of percent concentrations?

Answer 6

• m/m %
• v/v %
• m/v %

Question 7

Calculate the molarity (M) of a solution containing 6.00 g of NaOH in 0.500 L.

Answer 7

0.300 M.

Question 8

What is the formula for calculating dilution?

Answer 8

M₁V₁ = M₂V₂.

Question 9

What are colligative properties?

Answer 9

Properties that depend on the number of solute particles, such as freezing point depression and boiling point elevation.

Question 10

Fill in the blank: Water’s Kf is _______ °C·kg·mol⁻¹.

Answer 10

1.86

Question 11

Define isotonic, hypotonic, and hypertonic solutions.

Answer 11

• Isotonic: equal osmotic pressure
• Hypotonic: causes hemolysis
• Hypertonic: causes crenation

Question 12

What does Boyle’s Law state?

Answer 12

For fixed n and T, pressure is inversely proportional to volume (P₁V₁ = P₂V₂).

Question 13

What is STP and what is the molar volume of an ideal gas at STP?

Answer 13

STP is 0 °C and 1 atm; molar volume is 22.4 L/mol.

Question 14

What does the ideal gas law equation PV = nRT represent?

Answer 14

It relates pressure (P), volume (V), temperature (T), and amount of gas (n) using the gas constant (R).

Question 15

What does Dalton’s Law of Partial Pressures state?

Answer 15

Total pressure equals the sum of the partial pressures of component gases (Pₜ = ΣPᵢ).

Question 16

How do you convert mmHg to atm?

Answer 16

Divide by 760.

Question 17

What happens to the volume of a gas when the temperature increases at constant pressure?

Answer 17

The volume increases.

Question 18

What is the effect of pressure on gas volume according to Boyle’s Law?

Answer 18

Pressure and volume are inversely related.

Question 19

Fill in the blank: Molarity (M) is defined as _______.

Answer 19

mol solute per litre solution

Question 20

What is the effect of increasing temperature on the solubility of gases?

Answer 20

It decreases the solubility.

Question 21

What is the relationship between volume and moles of a gas at constant temperature and pressure according to Avogadro’s Law?

Answer 21

Volume is proportional to moles (V ∝ n).

Question 22

Define osmotic pressure.

Answer 22

The pressure required to prevent the flow of water across a semipermeable membrane.

Question 23

What is the formula for calculating mass percent concentration?

Answer 23

m/m % = (g solute / g solution) × 100.

Question 24

What does ‘like dissolves like’ mean in terms of solubility?

Answer 24

Polar solvents dissolve polar/ionic solutes; non-polar solvents dissolve non-polar solutes.

Question 25

What is the definition of energy?

Answer 25

Energy is the capacity to do work or supply heat.

Question 26

What is potential energy?

Answer 26

Stored energy (e.g., water behind a dam, chemical bonds).

Question 27

What is kinetic energy?

Answer 27

Energy of motion (e.g., flowing water, burning gasoline).

Question 28

What is the SI unit of energy?

Answer 28

Joule (J).

Question 29

How many joules are in one calorie?

Answer 29

4.184 J = 1 cal.

Question 30

What is the relationship between kilocalories and calories?

Answer 30

1 kcal = 1000 cal.

Question 31

What does temperature indicate?

Answer 31

Average kinetic energy.

Question 32

What are the three temperature scales?

Answer 32

* Kelvin (K) * Celsius (°C) * Fahrenheit (°F)

Question 33

What is the conversion formula from Celsius to Kelvin?

Answer 33

K = °C + 273.

Question 34

What is absolute zero in Kelvin?

Answer 34

0 K.

Question 35

What types of matter exist?

Answer 35

* Pure substance (element or compound) * Mixture

Question 36

How can mixtures be classified?

Answer 36

* Homogeneous * Heterogeneous

Question 37

What is a homogeneous mixture?

Answer 37

A mixture with a uniform composition (e.g., brass, air).

Question 38

What is a heterogeneous mixture?

Answer 38

A mixture with a non-uniform composition (e.g., salad, sandy water).

Question 39

What are the properties of solids?

Answer 39

Definite shape and volume; particles fixed and vibrating.

Question 40

What are the properties of liquids?

Answer 40

Definite volume; take the shape of the container; particles close but mobile.

Question 41

What are the properties of gases?

Answer 41

No fixed shape or volume; particles far apart and moving fast.

Question 42

What is the difference between physical and chemical properties?

Answer 42

* Physical properties: observed without chemical change (density, melting point, color). * Chemical properties: involve reactivity.

Question 43

What is a physical change?

Answer 43

A change that retains the identity of a substance.

Question 44

What is a chemical change?

Answer 44

A change that forms a new substance.

Question 45

What is specific heat (c)?

Answer 45

Specific heat = heat / (mass × ΔT), units J g⁻¹ °C⁻¹.

Question 46

What does a higher specific heat indicate?

Answer 46

A smaller temperature change (ΔT) for the same amount of heat (q).

Question 47

What is the heat equation?

Answer 47

q = m·c·ΔT.

Question 48

What are the food energy values for carbohydrates, proteins, and fats?

Answer 48

* Carbohydrates: 4 kcal g⁻¹ * Proteins: 4 kcal g⁻¹ * Fats: 9 kcal g⁻¹

Question 49

What is the specific heat of water?

Answer 49

4.184 J g⁻¹ °C⁻¹.

Question 50

Fill in the blank: The calorimeter measures heat of combustion converting to _______.

Answer 50

kcal.

Question 51

True or False: A burning candle is a physical change.

Answer 51

False.

Question 52

True or False: Ice melting is a chemical change.

Answer 52

False.