Inorganic Chemistry

How do the reactions of Li, Na, and K with water prove they are in the same chemical family?

They all react to produce a metal hydroxide (alkaline solution) and hydrogen gas, causing fizzing and floating.

How do reactions with water/air show the trend in reactivity down Group 1?

Reactivity increases down the group: Lithium fizzes slowly; Sodium melts into a ball and fizzes rapidly; Potassium ignites instantly with a lilac flame.

Predict the reactivity and reaction of Rubidium (Rb) with water.

Rubidium will react more violently than potassium, exploding instantly upon contact with water.

Explain the trend in Group 1 reactivity in terms of electronic configurations.

Down the group, atoms get larger and have more shells. The outer electron is further from the nucleus, less attracted to it, and more easily lost.

State the trends in physical properties down Group 7.

Melting and boiling points increase down the group, and the colors become darker.

Predict the physical state and color of Astatine (At) at room temperature.

Black solid (following the trend of increasing density and darker color down the group).

How do halogen displacement reactions provide evidence for the reactivity trend?

A more reactive halogen displaces a less reactive halide from its solution (e.g., Cl2 turns KBr solution orange as bromine is displaced), showing reactivity decreases down the group.

Explain the trend in Group 7 reactivity in terms of electronic configurations.

Down the group, atoms get larger. The outer shell is further from the nucleus, making it harder to attract and gain an incoming electron.

Briefly describe how to determine the % of oxygen in air using phosphorus.

Trapped air is exposed to burning phosphorus in a graduated tube over water; phosphorus consumes the oxygen, causing water to rise by exactly (approx 21%).

Describe the combustion of Hydrogen (\(\text{H}_{2}\)) in oxygen.

Burns explosively with a pale blue flame to produce water vapor (H2O).

Write the word and chemical equation for the thermal decomposition of copper(II) carbonate.

Copper(II) carbonate to Copper oxide + Carbon dioxide and CuCO3 (green) to CuO (black)+ CO2

What happens when Magnesium is heated with Copper(II) Oxide (\(\text{CuO}\))?

A displacement reaction occurs because Mg is more reactive than Cu: Mg + CuO to MgO + Cu

Define Oxidation and Reduction in terms of Oxygen.

Oxidation = Gain of oxygen. Reduction = Loss of oxygen.

Define Oxidation and Reduction in terms of Electrons.

Oxidation Is Loss, Reduction Is Gain of electrons.

Define Redox reaction.

A reaction where both oxidation and reduction occur at the same time.

What is an Oxidising Agent?

A substance that gives away oxygen OR gains electrons (it gets reduced itself).

What is a Reducing Agent?

A substance that removes oxygen OR loses electrons (it gets oxidized itself).

Where are most metals found, and how are unreactive metals found?

Most metals are extracted from compounds/ores in the Earth's crust; unreactive metals (like gold) are found native as uncombined elements.

How is extraction method linked to the reactivity series?

Metals below carbon are extracted by reduction with carbon; metals above carbon are too reactive and must be extracted using electrolysis.

State the specific use and property for Aluminium.

Airplane bodies (low density) or electricity cables (good conductor, low density).

State the specific use and property for Copper.

Electrical wiring (excellent conductor, ductile) or water pipes (unreactive, malleable).

Match the types of Steel to their properties/uses.

Low-carbon (mild) = malleable (car bodies); High-carbon = hard/brittle (cutting tools); Stainless = corrosion-resistant (cutlery).

What is an alloy and why is it harder than a pure metal?

A mixture of a metal with other elements. The different-sized atoms disrupt the regular layers, preventing them from sliding over each other.

Classify the following pH ranges: 0-3, 4-6, 7, 8-10, 11-14.

0–3: Strongly acidic | 4–6: Weakly acidic | 7: Neutral | 8–10: Weakly alkaline | 11–14: Strongly alkaline.

What is used to measure the approximate pH value of an aqueous solution?

Universal indicator (by matching its color change to a pH color chart).

Core steps to carry out an Acid-Alkali Titration.

1. Use a pipette to add alkali to a conical flask with indicator. 2. Fill a burette with acid. 3. Add acid dropwise until the indicator changes color permanently (end-point). 4. Record the volume.

Define an Acid and a Base in terms of proton transfer.

An Acid is a proton (H+) donor. A Base is a proton (H+) acceptor.

Why is the reaction between Nitric Acid and metals excluded from general rules?

Nitric acid is a powerful oxidising agent and usually produces water and nitrogen oxides instead of hydrogen gas.

What is the structural difference between a Base and an Alkali?

Bases are metal oxides, hydroxides, or ammonia. An alkali is simply a base that is soluble in water.

How do you prepare a pure, dry sample of a soluble salt from an insoluble reactant (e.g. CuSO4) from CuO)?

1. Add excess insoluble base to warm acid. 2. Filter out unreacted excess. 3. Heat filtrate to crystallization point, leave to cool, then filter and dry the crystals.

How do you prepare a pure, dry sample of a soluble salt from an acid and alkali?

1. Carry out a titration with indicator to find the exact neutralization volumes. 2. Repeat without indicator using those exact volumes. 3. Evaporate and crystallize the salt.

How do you prepare a pure, dry sample of an insoluble salt (e.g. PbSO4)?

Precipitation method: 1. Mix two soluble salt solutions. 2. Filter to collect the insoluble precipitate. 3. Wash the residue with distilled water. 4. Dry in a warm oven.

Describe how to carry out a Flame Test.

Dip a clean platinum or nichrome wire into concentrated hydrochloric acid, touch the sample, and hold it in a roaring blue Bunsen flame.

Test and positive result for Ammonium ions (NH4+).

Add aqueous sodium hydroxide (NaOH) and warm gently; toxic ammonia gas is evolved, which turns damp red litmus paper blue.

What chemical is added before silver nitrate or barium chloride in ion tests and why?

Dilute nitric/hydrochloric acid; it removes any carbonate ions that would otherwise form a false white precipitate.

Chemical test for the presence of water.

Add the liquid to anhydrous copper(II) sulfate; it changes color from white to blue.

Physical test to show whether a sample of water is pure.

Measure its boiling point; pure water boils at exactly 100°C (impurities raise the boiling point or melt over a range).