Chemistry (Unit 1) R#3 Flashcards

Question

What is a solution?

Answer 1

A mixture of the solute dissolved in solvent.

Answer 2

When the maximum amount of solute has been dissolved in a solvent at a certain volume and temperature.

Answer 3

Solubility in g of solute/100g of water over temperature.

Answer 4

1. Find the mass dissolved at the initial temperature 2. Find the maximum mass that can be dissolved at final temperature 3. The difference between the masses is the mass that will crystalise due to decrease in temperature

Answer 5

A pure substance made of only one type of atom ## Footnote Elements are the simplest form of matter and cannot be broken down into simpler substances.

Answer 6

Two or more different elements chemically bonded in a fixed composition ## Footnote Compounds have unique properties that differ from the individual elements that compose them.

Answer 7

Two or more different substances physically bonded not in a fixed composition ## Footnote Mixtures can be separated by physical means.

Answer 8

Use a magnet as iron is magnetic ## Footnote This method exploits the magnetic property of iron.

Answer 9

Dissolve the mixture in water, filter to remove sand, and evaporate the water to get salt ## Footnote This uses solubility and filtration techniques.

Answer 10

Filter to obtain solid (filtration) ## Footnote Filtration is effective for separating solids from liquids.

Answer 11

Simple distillation ## Footnote Simple distillation involves heating the solution to vaporize the liquid and then condensing it back to liquid.

Answer 12

* Heat till point of crystallisation to evaporate water * Leave to cool to form crystals * Filter the solution to remove crystals as residue * Dry between 2 filter papers ## Footnote Crystallization allows for the formation of pure solid crystals from a solution.

Answer 13

Using a filtering funnel ## Footnote Immiscible liquids do not mix and can be separated based on density.

Answer 14

Fractional distillation to separate based on different boiling points ## Footnote Fractional distillation is useful for separating mixtures of liquids with close boiling points.

Answer 15

1. The mixture is heated and vaporised 2. Vapours rise up the fractionating column 3. Fractionating column has a temperature gradient (cooler at the top than the bottom) 4. Substance with lowest/lower boiling point is affected first 5. Seperation depends on the difference in boiling points

Answer 16

1. Draw the baseline in pencil. 2. Use food colorings/inks/dyes and a chromatography paper. 3. Place inks (etc.) on the baseline. 4. Place the paper into the beaker with the start line above the solvent. 5. Remove paper when spots stop moving. 6. Mark the solvent front. 7. Remove the paper and allow it to dry. ## Footnote Chromatography is a technique for separating mixtures based on the movement of substances across a medium.

Answer 17

It indicates a pure substance ## Footnote A single mark shows that the dye has not mixed with any other substances.

Answer 18

The dye is insoluble in the solvent ## Footnote This means the dye cannot dissolve in the solvent used.

Answer 19

Each mark is a different substance in the mixture of the dye ## Footnote Multiple marks indicate the presence of various components in the dye.

Answer 20

Rf value = distance travelled by solute from baseline / distance moved by solvent from baseline ## Footnote The Rf value helps in identifying substances based on their movement in the solvent.

Answer 21

Smallest form of element that carries its properties ## Footnote Atoms are the fundamental building blocks of matter.

Answer 22

A group of two or more atoms chemically combined to form an identifiable unit which retains the properties and composition of the substance

Answer 23

What an atom is composed of ## Footnote Subatomic particles include protons, neutrons, and electrons.

Answer 24

+ve SAP with 1 amu ## Footnote Protons are positively charged particles found in the nucleus of an atom.

Answer 25

-ve SAP with negligible mass ## Footnote Electrons are negatively charged particles that orbit the nucleus of an atom.

Answer 26

0 charge SAP with 1 amu ## Footnote Neutrons are neutral particles found in the nucleus of an atom.

Answer 27

Total mass of atom | no. protons + no. neutrons (larger no. in PT) ## Footnote Mass number represents the total number of protons and neutrons in an atom.

Answer 28

Total no. of protons (smaller no. in PT) ## Footnote Atomic number defines the identity of an element and its position in the periodic table.

Answer 29

Atom has P > e- so it’s positively charged (X+) ## Footnote This process is known as ionization, resulting in a cation.

Answer 30

Atom has P < e- so it’s negatively charged (X-) ## Footnote This process results in an anion.

Answer 31

2 e- ## Footnote The first shell can hold a maximum of 2 electrons.

Answer 32

8 e-/shell ## Footnote Each shell after the first can hold up to 8 electrons.

Answer 33

Atoms of the same element with the same number of protons but different number of neutrons. ## Footnote They have the same chemical properties due to having the same electronic configuration.

Answer 34

The average mass number of all isotopes of an element compared with the mass of carbon-12

Answer 35

Use the formula: (M1 x P1) + (M2 x P2) … / 100. ## Footnote Where M is mass and P is the percentage of each isotope.

Answer 36

35.5 ## Footnote Calculation: (35 x 75) + (37 x 25) / 100.

Answer 37

Find the ratio of differences between masses and RAM, then cross-multiply with total and 100 to get percentages. ## Footnote Example: For Ca-39 and Ca-42 with RAM = 40.12, the ratios are used to find percentages.

Answer 38

Ca-39 = 37.3%, Ca-42 = 63.7%. ## Footnote Calculated using the ratios 1.12 : 1.88 : 3.

Answer 39

Metallic character increases ## Footnote This refers to the tendency of elements to exhibit physical and chemical properties characteristic of metals.

Answer 40

Most elements are solids ## Footnote Exceptions include hydrogen (H), oxygen (O), nitrogen (N), group 7 gases, and the liquids mercury (Hg) and bromine (Br).

Answer 41

8 groups ## Footnote Each group has specific characteristics based on the number of outer electrons.

Answer 42

Number of outer electrons ## Footnote This is crucial for understanding an element's reactivity and bonding behavior.

Answer 43

Alkali metals ## Footnote These metals are highly reactive and include lithium, sodium, and potassium.

Answer 44

Halogens ## Footnote Halogens are reactive nonmetals, including fluorine, chlorine, bromine, iodine, and astatine.

Answer 45

Noble gases ## Footnote These gases are characterized by having a full outer shell of electrons, making them largely unreactive.

Answer 46

Number of shells ## Footnote This indicates the energy levels of electrons in an atom.

Answer 47

Write as is in the Periodic Table. If an ion is present, add the charge.

Answer 48

Write as is given and check for any prefixes. | Example: Carbon monoxide = CO Dinitrogen pentoxide = N₂O₅

Answer 49

1. Write the symbols of each of the elements. 2. Write the valences of each element above the equation. 3. Simplify where possible.

Answer 50

+1 (NH₄⁺)

Answer 51

* Nitrate (NO₃⁻) * Nitrite (NO₂⁻) * Hydroxide (OH⁻)

Answer 52

* Sulphite (SO₃²⁻) * Sulphate (SO₄²⁻) * Carbonate (CO₃²⁻)

Answer 53

Equations that use only words, not symbols. | Example: Carbon dioxide + water → glucose + oxygen

Answer 54

1. Write full formulas for all reactants and products. 2. Balance the equation so all reactants = all products. | Example: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Answer 55

Only water, bromine, and mercury are liquids at room temperature and pressure (rtp).

Answer 56

Only O₂ N₂ H₂ Cl₂ F₂ CO CO₂ SO₂ NO₂ NH₃ are gases

Answer 57

All other elements not mentioned as liquids or gases.

Answer 58

1. All group 1, ammonium, and nitrate compounds are aqueous. All acids are aqueous. 2. All sulfate and sulfite compounds are aqueous except: Silver (Ag), Calcium (Ca), Barium (Ba), Lead (Pb). 3. All halide (Group 7) compounds are aqueous except: Silver (Ag), Lead (Pb). 4. All silver compounds are solid except Silver Nitrate (AgNO₃, aqueous). 5. All metal oxides, hydroxides, and carbonates are solid except if they contain group 1 metals or ammonium.

Answer 59

1. Oxidation involves the gain of oxygen. 2. Oxidation is the loss of electrons. (OIL: Oxidation Is Loss).

Answer 60

A redox reaction is a reaction that involves both oxidation and reduction.

Answer 61

An oxidizing agent is the substance that causes oxidation by gaining electrons (and, therefore, getting reduced).

Answer 62

A reducing agent is a substance that causes reduction by losing electrons (and, therefore, getting oxidized).

Answer 63

The reactivity series ranks metals by their reactivity, with Group 1 being the most reactive and Group 3 being the least reactive. * Group 1: Potassium (K), Sodium (Na), Lithium (Li), Calcium (Ca), Magnesium (Mg) * Group 2: Magnesium (Mg), Aluminium (Al), Zinc (Zn), Iron (Fe), Tin (Sn), Lead (Pb) * Group 3: Hydrogen (H+), Copper (Cu), Silver (Ag), Gold (Au), Platinum (Pt)

Answer 64

Metals in Group 1 (e.g., Potassium, Sodium, Lithium) react with cold water and below (steam, acid). * With cold water: metal hydroxide + hydrogen * With acid: salt + hydrogen

Answer 65

Metals in Group 2 (e.g., Magnesium, Calcium) react with steam and below (acid). * With steam: metal oxide + hydroxide * With acid: salt + hydrogen

Answer 66

Metals in Group 3 (e.g., Copper, Silver, Gold) have very low reactivity and do not react under normal conditions.

Answer 67

Precision refers to the number of decimal places a value is accurate to. The more decimal places, the more precise the measurement.

Answer 68

An experiment is reliable when it is repeated more than once and consistently yields similar results.

Answer 69

Accuracy refers to using the correct apparatus for measurements to ensure the values are correct and close to the true value.

Answer 70

Group 1 metals are extracted by electrolysis because they are more reactive than carbon.

Answer 71

Group 2 metals are extracted by reduction with carbon because they are less reactive than carbon.

Answer 72

Group 3 metals are mostly found free in nature because they have very low reactivity and do not react with their surroundings.

Answer 73

1. Bauxite ore (Al₂O₃): Pure source of aluminium oxide. 2. Cryolite: Lowers the melting point of aluminium oxide. 3. Graphite (carbon): Used to make electrodes for electrolysis.

Answer 74

At the cathode (-ve terminal), aluminium metal is produced. * Half equation: Al³⁺ + 3e⁻ → Al.

Answer 75

At the anode (+ve terminal), oxygen gas (O₂) is produced. * Half equation: 2O²⁻ → O₂ + 4e⁻ * The oxygen reacts with the carbon in the graphite electrode, forming CO₂: C + O₂ → CO₂.

Answer 76

1. Body of aeroplanes: Low density. 2. Cooking pans: Good conductor of heat, non-toxic, resistant to corrosion.

Answer 77

1. Coke (carbon): Acts as a reducing agent and source of heat. 2. Haematite ore (Fe₂O₃): Main source of iron oxide. 3. Water: Acts as a cooling agent. 4. Hot air: For combustion. 5. Limestone (CaCO₃): Purifies iron from sand.

Answer 78

Iron (II) oxide (FeO) is reduced by coke and carbon monoxide in the blast furnace to produce iron.

Answer 79

1. Iron from the blast furnace is purified by blowing hot oxygen over it to remove impurities. 2. Carbon is added to form steel (an alloy).

Answer 80

Alloys are mixtures of a metal and one or more other elements (usually carbon). They have improved properties, such as increased hardness due to the distorted arrangement of atoms.

Answer 81

1. Low % carbon steel / Mild steel (0.25%): Easily shaped, used for car bodies. 2. High % carbon steel (2.5%): Harder, used for cutting tools. 3. Stainless steel (Fe/Cr/Ni): Resistant to corrosion, used for cutlery and sinks. Expensive.

Answer 82

1. Railway tracks: High strength. 2. Car bodies: Strong, malleable.

Answer 83

1. Electric wiring: Ductile and good conductor of electricity. 2. Sauce pans: Malleable, good conductor of heat, unreactive.

Answer 84

Iron rusts in the presence of water and oxygen, forming iron (III) oxide.

Answer 85

1. Painting: Used for steel bridges and railings. 2. Oiling/Greasing: Used for tools, machine parts, and bicycle chains. These methods prevent water and oxygen from reaching the iron. If scratched, they no longer prevent rust.

Answer 86

Galvanizing: Iron is coated with zinc. Zinc acts as a barrier and is more reactive than iron. When scratched, zinc oxidizes instead of the iron, protecting it. * Zinc equation: Zn → Zn²⁺ + 2e⁻ * Iron equation: Fe → Fe²⁺ + 2e⁻

Answer 87

All acids contain the H⁺ ion (proton donor) when released in water (aqueous).

Answer 88

1. Completely ionized in water. 2. Large number of H⁺ ions released when added to water. 3. pH = 0-3.

Answer 89

1. Incompletely ionized in water. 2. Low number of H⁺ ions released when added to water. 3. pH = 4-6.

Answer 90

* Dilute acid: Acid with a lot of water added. * Concentrated acid: Acid with little or no water added.

Answer 91

All acids are strong except those with carbon (C) or sulfite (SO₃²⁻).

Answer 92

All bases and alkalis contain the OH⁻ ion (proton acceptor) when released in water.

Answer 93

* Alkalis are soluble bases (e.g., Group 1 oxides, hydroxides, ammonium hydroxide). * Bases can be insoluble or soluble in water.

Answer 94

1. Contain Group 1 metals. 2. pH = 11-13.

Answer 95

1. Do not contain Group 1 metals. 2. pH = 8-11.

Answer 96

Acid + Base → Salt + Water (Neutralization). This reaction involves a proton donor (acid) and a proton acceptor (base) to produce water.

Answer 97

Because it involves a proton donor (H⁺ ) and a proton acceptor (OH⁻) to give water

Answer 98

Acid + Carbonate → Salt + Water + Carbon Dioxide.

Answer 99

pH is the measure of the number of H⁺ or OH⁻ ions given by one molecule of a substance.

Answer 100

Indicators change color based on the pH of the solution. * Litmus solution: Red in acid, purple in neutral, blue in base. * Phenolphthalein: Colorless in acid, pink in base. * Methyl orange: Red in acid, orange in neutral, yellow in base. * Universal indicator: Dark red in strong acid, green in neutral, purple in strong base.

Answer 101

Only for Group 1 metal and ammonium compounds. 1. Use a pipette to measure exact volumes and a burette for accurate variable volumes. 2. Mix the acid and base, and crystallize the solution to obtain dry crystals. 3. Example: Prepare NaCl crystals from NaOH and HCl. * Titrate HCl into NaOH until the indicator changes color. * Crystallize the solution to obtain NaCl.

Answer 102

* Titration: Used for Group 1 metal and ammonium salts. * Dissolving: Used for making salts that do not contain Group 1 metals or ammonium; add solid base until the acid is used up, then filter to remove excess base.

Answer 103

1. Add two aqueous solutions to a beaker. 2. Stir until a solid forms. 3. Filter to obtain the solid as residue. 4. Wash with distilled water. 5. Leave to dry in a warm place. **Standard equation state symbols:** (aq) + (aq) → (s) + (aq)

Answer 104

The mole (mol) is the unit for the amount of a substance

Answer 105

Moles (mol) = Mass (g) / Molar mass (Ar or Mr).

Answer 106

Moles (mol) = Concentration (mol/dm³) × Volume (dm³). ## Footnote Convert volume from cm³ to dm³ (1 dm³ = 1000 cm³).

Answer 107

Moles (mol) = Volume (dm³) / 24. ## Footnote Only use this if the gas is at room temperature and pressure (r.t.p.), or if it’s stated that 1 mole of gas occupies 24 dm³.

Answer 108

Moles (mol) = Number of particles / Avogadro’s constant (6.02 × 10²³).

Answer 109

Mole ratios are the ratios between the coefficients of reactants and products in a balanced chemical equation. These ratios can be used to calculate the moles of substances involved in the reaction.

Answer 110

An empirical formula is the simplest whole number ratio of elements in a compound. Steps to find it: 1. Divide the mass of each element by its atomic mass (Ar). 2. Divide the ratios by the smallest ratio. 3. Approximate if necessary, but avoid ratios like 0.5, 0.33, or 0.25.

Answer 111

A chemical formula that gives the total number of atoms of each element present in a molecule.

Answer 112

Molecular formula = n × Empirical formula. To find "n": 1. Calculate the Mr of the empirical formula. 2. Divide the given Mr by the empirical formula’s Mr. 3. Multiply the empirical formula by "n" to get the molecular formula.

Answer 113

(80 / 12) : (20 / 1) 80% C = 6.67 20% H = 20 Divide by the smallest value (6.67): 1 : 3 Empirical formula = CH₃. Molecular formula: mass of CH₃ = 15 (12 =3x1) n = 45/15 = 3 So, C₃H₉

Answer 114

Percentage yield = (Actual yield / Theoretical yield) × 100.

Answer 115

Percentage of atom = (Ar of atom / Mr of compound) × 100.

Answer 116

1. Find the mass of substance and water: 2. Write the ratio: 3. Calculate moles of each: 4. Find the ratio: 5. Conclusion: The X value is 10, so the formula is FeSO₄·10H₂O. Workout: * Mass of FeSO₄ = 16g - 10g = 6g * Mass of water = 20g - 16g = 4g * FeSO₄ : Water = 6g : 4g * Moles of FeSO₄ = 6 / 152 = 0.04 mol * Moles of H₂O = 4 / 18 = 0.22 mol * Divide by the smallest value: * FeSO₄: 0.04/0.04 = 1 * Water: 0.4/0.04 = 10

Answer 117

1. Add reactants together. 2. Reactants take in required energy from surroundings to break their bonds (activation energy, endothermic part). 3. Free electrons collide together to form new bonds, releasing energy (exothermic part). 4. Enthalpy change (ΔH) = Energy of reactants – Energy of products.

Answer 118

Activation energy is the energy required to break the bonds in the reactants. It is the endothermic part of the reaction.

Answer 119

Enthalpy change = Energy of reactants – Energy of products. * A negative value indicates an exothermic reaction. * A positive value indicates an endothermic reaction.

Answer 120

* Exothermic: A reaction that releases thermal energy to its surroundings. * Endothermic: A reaction that absorbs thermal energy from its surroundings.

Answer 121

* Exothermic: Energy released during bond making is greater than energy absorbed during bond breaking. * Endothermic: Energy released during bond making is less than energy absorbed during bond breaking.

Answer 122

1. Heat is lost to surroundings. 2. Impure substances are used. 3. Incomplete combustion.

Answer 123

1. Identify if the reaction is exothermic or endothermic. 2. Label reactants and products. * For exothermic: Products have lower energy than reactants. * For endothermic: Products have higher energy than reactants.

Answer 124

Use the equation: Q = mcΔT * m: Mass or volume of water or solutions used in the experiment. * c: Specific heat capacity (4.2 J/g°C for water). * ΔT: Rise in temperature. ## Footnote This gives energy in joules (J).

Answer 125

Method 1: ΔH = Energy of reactants – Energy of products. * If ΔH is negative, the reaction is exothermic. Method 2: Molar enthalpy change = Energy in kJ / Number of moles. * ΔH = Q (kJ) / Moles.

Answer 126

Compounds that contain carbon and hydrogen. There are an infinite number of organic compounds.

Answer 127

A group of organic compounds with: * The same functional group * The same general formula * Similar chemical properties * A gradual change in physical properties * A difference of CH2 between consecutive members

Answer 128

An atom or group of atoms bonded in a specific arrangement that determines the chemical properties of a homologous series.

Answer 129

Prefix: Based on the number of carbon atoms (Meth-1, Eth-2, Prop-3, But-4, etc.) Suffix: * Alkane: -ane * Alkene: -ene * Alcohol: -anol * Carboxylic Acid: -anoic acid * Ester: -yl...anoate

Answer 130

* 1-4 carbons: Gas * 5-15 carbons: Liquid * >15 carbons: Solid

Answer 131

Compounds made up of only hydrogen and carbon.

Answer 132

Compounds with the same molecular formula but different displayed formula.

Answer 133

Pentane (C5H12)

Answer 134

قص و الظق في النوص

Answer 135

Substitution: in the presence of halogens and UV light * Example: CH4 + Br2 → CH3Br + HBr Combustion: complete and incomplete * Complete: Produces CO2 + H2O * Incomplete: Produces CO + H2O (or soot if oxygen is very low) Cracking: Breaking down large hydrocarbons into smaller, more useful alkanes and alkenes

Answer 136

The presence of a carbon to carbon double bond (C=C).

Answer 137

By moving the position of the double bond. | Example: * But(1)ene → C=C-C-C * But(2)ene → C-C=C-C

Answer 138

The unstable repulsion force between the two bonds makes them highly reactive.

Answer 139

Combustion (same as alkanes) Addition reactions (breaking the double bond to add atoms): * Hydrogenation: (+H2) → Forms an alkane (Requires Ni catalyst) * Hydration: (+H2O) → Forms an alcohol (Requires H3PO4, 300°C, 65 atm, steam) * Bromination: (+Br2) → Forms dibromo compounds (Orange bromine water turns colorless)

Answer 140

A mixture of different alkanes.

Answer 141

Fractional distillation separates the fractions based on their boiling points. Crude oil is vaporised into a mixture of gases. This mixture rises up through a fractionating column where the temperature at the top is cooler than the temperature at the bottom, creating a temperature gradient. This causes the fractions with the lower boiling points to collect at the top and the fractions with the higher boiling points to collect near the bottom. (If asked about a particular fraction, state its general position and what fractions are beneath and above it.)

Answer 142

* Refinery Gas * Gasoline (Petrol) * Kerosene (Paraffin) * Diesel * Fuel Oil * Bitumen

Answer 143

* Higher boiling point * More viscous * Darker color * Less flammable * Less volatile * Lower market demand and price

Answer 144

* Definition: The breakdown of long-chain hydrocarbons into shorter-chain hydrocarbons * Conditions: 600-700°C with a silica/alumina catalyst. **Importance:** 1. Fractional distillation produces long-chain alkanes which are in lower demand due to fewer uses for them 2. Shorter-chain alkanes are more useful as they are more flammable and can be used as fuels 3. Produces alkenes which aren't naturally occuring and are used to make polymers

Answer 145

1. Cracking of crude oil 2. Dehydration of alcohols (Using H3PO4, 300°C, 65 atm)

Chemistry (Unit 1) R#3 Flashcards

(184 cards)