C5 - Chemical Changes Flashcards
What is the most reactive element in the reactivity series?
Potassium
What is the least reactive element in the reactivity series?
Platinum
What will happen if a more reactive metal reacts with a less reactive metal?
The more reactive metal will displace the less reactive metal
What happens when an acid reacts with a metal?
They produce a salt and hydrogen gas
What happens when an acid reacts with a metal oxide?
They produce salt and water
What happens when an acid reacts with a metal carbonate?
They produce salt, water and carbon dioxide
What is an acid?
A substances that releases hydrogen (H+) ions when dissolved in water
What is the defenition of an alkali?
A base which disolves in water and releases hydroxide ions (OH-) when dissolved in water
What is a neutralisation reaction?
A reaction where an acid reacts with a base to form a salt and water
What would you call a substance with a pH of less than 7?
An acid
What is the range of the pH scale?
0-14
What would you call a substance with a pH of exactly 7?
A neutral substances, such as pure water
What are 2 ways of measuring the pH of a substance?
- Using an indicator such as a chemical dye which changes colour based on how acidic or alkali a substance is
- Using a pH probe, which tells you the pH of a substance
Why might it be better to use a pH probe than a chemical dye to measure pH?
As the pH probe is likely to be more accurated then the chemical dye as it does not involve human judgement
What would you call a substance with a pH of more than 7?
A base
What are alkalis compared to bases?
Alkalis are a sub-group of bases which are soluble in water
If a substances is a red or orange colour after using a chemical dye what pH’s is it likely to be?
Any pH from 0-6
Red from 0-3 and orange from 4-6
If a substance is a blue or purple colour after using a chemical dye what pH’ is it likely to be?
pH of 8-14
8-10 for blue, 11-14 for purple
If a substance is green after using a chemical dye what pH is it likely to be?
pH 7 (neutral)
