(Done) Chemical Changes (Paper 1) Flashcards
(25 cards)
What is the pH scale
- A measure of how acidic or alkaline a solution is
How can the pH of a solution be measured
- Indicator
- pH probe
What ion do acids contain whilst dissolved in water
- H+
What ions do alkaline form whilst dissolved in water
- OH-
What determines the strength of an acid
- How many acid particles dissociate to release H+ ions, the more particles dissociate and the more H+ ions, the stronger the acid
What type of scale is the pH scale
- A 10x logarithmic scale
What metal molecules (bases) react with acid to form salt and water
- Metal oxides and metal hydroxides
What metal molecules react with acid to form salt, water and carbonate
- Metal carbonates
How can you make soluble salts
- Using an acid an an insoluble base
Reactivity series from least to most reactive
- Copper
- Hydrogen
- Iron
- Zinc
- Carbon
- Magnesium
- Calcium
- Lithium
- Sodium
- Potassium
How can you determine the reactivity of a metal with acid
- By measuring the speed of the reaction through measuring the amount of bubbles produced per unit time
What element is used in basic oxygen reduction
- Carbon
What elements can be reduced with carbon
- Zinc
- Iron
- Copper
Define oxidation reaction
- A displacement reaction where either oxygen is gained or electrons are lost
Define reduction reaction
- A displacement reaction where oxygen is lost or electrons are gained
What are ionic equations
- Equations that only show the particles that react and the products they form
Define electrolyte
- A molten or dissolved ionic compound
What happens at the cathode (-ve electrode) in electrolysis
- Positive ions in the electrolyte gather and become reduced
What happens at the anode (+ve electrode) in electrolysis
- Negative ions in the electrolyte gather and become oxidised
What happens during electroylsis
- An electric current is passed through an electrolyte
- The ions move towards the electrodes, where they react, and the compound decomposes
- This creates a flow of charge through the electrolyte due to the flowing ions
- As ions gain or lose electrons, they form the uncharged element and are discharged from the electrolyte
Why can’t an ionic solid be electrolysed
- The ions are fixed in position and are unable to move
What happens to positive metal ions in electroylsis
- Reduced to the element at the cathode
What happens to negative non-metal ions in electrolysis
- Oxidized to the element at the anode
What is cryolyte
- An aluminum based compound used as an electrolyte in electrolysis
