chemical changes

what colours are shown to the 3 phs of litmus paper

acid red

neutral blue

alkaline purple

what colours does methayl orange

acidic red

neutral orange

alkaline yellow

what colours does phenolophin show

acid colourless

neutral colourless

alkaline purple

what happenes during electrolysis

Electrolysis is the breakdown of an ionic compound using electricity when it is molten or dissolved in water.

• Cathode (−): Positive ions gain electrons (reduction).

• Anode (+): Negative ions lose electrons (oxidation).

summary of electrolysis in aqueous solution

1. Aqueous electrolysis is electrolysis of an ionic compound dissolved in water.

the 2 products are in the solution of the beaker as normal but hydrogen(plus) and hydroxide(negative) are also present becvause its a liquid

the posotive ion and hydrogen ion go to the cathode where only 1 is neutralised it is the one which is less reactive,lower on series

negative product and hydroxde ions go to anode where if a halide(group 7) is present it gets neutralised if not it is always the hydroxide ion

extracting metals what do i need to know about weasther to use carbon or electrolysis

Remember that metals above carbon need electrolysis to be extracted, while metals below carbon can be extracted using carbon.

how to remember reactivity series

“Please Stop Calling Me A Cute Zebra, I Hate Copper Silver Gold.”

• Potassium

• Sodium

• Calcium

• Magnesium

• Aluminium

• Carbon

• Zinc

• Iron

• Hydrogen

• Copper

• Silver

• Gold

what does the la chatlier principle mean

if you were to change the conditions on one side of the equation the other side will counteract this by doing the same thing on the other side so that they can stay equal

explain 2 reasons farmers use fertilisers on there field

provides minerals

helps crops grow faster

• Why are pure metals malleable, but alloys are hard and strong? (Explain using atomic structure).

• What are the specific components and properties of:

  1. Low-carbon steel vs. High-carbon steel vs. Stainless steel

  2. Brass vs. Bronze

• What are the primary GCSE uses for pure Aluminium, Copper, and Gold?

1. The Structural Difference (The "Why")

• Pure Metals: Arranged in a regular lattice of identical-sized atoms. The layers can easily slide over each other when a force is applied, making pure metals soft and malleable.

• Alloys: A mixture of a metal with another element. The different-sized atoms distort the regular layers, which prevents the layers from sliding, making alloys much harder and stronger.

2. Core Edexcel Alloys to Memorise

• Low-carbon steel: Iron + low % carbon \(\rightarrow \) Malleable (Uses: Car bodies, ship hulls).

• High-carbon steel: Iron + high % carbon \(\rightarrow \) Hard and brittle (Uses: Cutting tools, masonry nails).

• Stainless steel: Iron + chromium + nickel \(\rightarrow \) Corrosion-resistant (Uses: Cutlery, chemical vessels).

• Brass: Copper + zinc \(\rightarrow \) Resistant to corrosion, low friction (Uses: Plumbing fixtures, musical instruments).

• Bronze: Copper + tin \(\rightarrow \) Tough and corrosion-resistant (Uses: Statues, ship propellers).

3. Properties & Uses of Specific Pure Metals

• Aluminium: Low density and forms a protective oxide layer (Uses: Aircraft bodies, overhead power cables).

• Copper: Excellent electrical conductor and ductile (Uses: Electrical wiring, saucepan bases).

• Gold: Very unreactive and shiny, but 24-carat gold is too soft on its own \(\rightarrow \) alloyed with copper/silver for jewellery to increase hardness.

Magnesium sulfate solution can be electrolysed using the apparatus shown in Figure 7.Explain how the products are formed at the electrodes in terms of • the ions present in the solution • the oxidation and reduction reactions that take place at the electrodes.

Mg2+ and SO42- ions are present in magnesium sulfate solution • water splits to form H+ and OH- ions • negative ions / anions move positive electrode / anode • sulfate ions / SO42- and hydroxide / OH- ions move to anode • can credit ions shown on diagram • hydroxide ions / OH- lose electrons • loss of electrons is oxidation • hydroxide ions are oxidised • 4OH- → O2 + 2H2O + 4e- • positive ions / cations move to negative electrode / cathode • magnesium ions / Mg2+ and hydrogen ions / H+ move to cathode • hydrogen forms as it’s less reactive than magnesium • hydrogen ions / H+ gain electrons • gain of electrons is reduction • hydrogen ions are reduced • 2H+ + 2e- → H2