Chemical Change Flashcards
(10 cards)
What is the equation between a metal and an acid?
Metal + Acid → Salt + Hydrogen.
Which element is used to extract a metal from its oxide?
Carbon, but only if the metal is less reactive than carbon.
What is the ionic equation for neutralisation?
Hydrogen⁺ + Hydroxide⁻ →
H₂O.
Why are some acids stronger than others?
Stronger acids completely ionise, whereas weaker acids only partially ionise.
What is the process of electrolysis in aqueous solutions?
- Least reactive positive ion will be reduced (often hydrogen).
- Metal ion will only be reduced if below hydrogen on reactivity series.
- If negative ion is a halogen, it will be oxidised. If not, then hydroxide⁻ will be oxidised to form water and oxygen.
Why do ionic substances not conduct electricity?
They contain charged ions, but they are in fixed positions and are not free to flow throughout the entire structure.
Why is hydrogen often given off at the cathode?
More easy to reduce than other positively charged ions in solution, meaning they readily gain electrons.
Why is cryolite mixed with aluminium oxide?
Reduces melting point, saving energy.
What is produced at the cathode?
Least reactive positive ion.
What is produced at the anode?
Oxygen gas, unless halide ions (chloride, bromide or iodide) are present.
