C5 - Chemical Changes Flashcards Preview

Chemistry - 2 Chemical Reactions and Energy Changes > C5 - Chemical Changes > Flashcards

Flashcards in C5 - Chemical Changes Deck (28):

Reactivity Series Order Highest - Lowest

Potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, tin, lead, copper, silver, gold.


How is the reactivity series ordered?

Placed in orders by their reactions with water and dilute acid.


What happens when hydrogen is given off the reaction?

The gas pops with a lighted spill.


What will happen if a more reactive metal and a less reactive metal come together?

The more reactive metal will displace a less reactive metal from its aqueous solution.


Why can non-metals hydrogen and carbon be given positions in the reactivity series?

The basis of displacement reaction.


What is oxidation?

- The loss of electrons.


What is reduction?

The gain of electrons.


What is a metal ore?

- Contains enough of the metal to make it economic to extract the metal.
- Ores are mined and might need to be concentrated before the metal is extracted and purified.


How can un-reactive metals be founded?

In their native state.


How can the reactivity series help you with metal extraction?

- Decides the best way to extract a metal from its ore.
- Oxides of metals below carbon in the series can be reduced by carbon to give the metal element.


How are more reactive metals than carbon extracted?

- Cannot be extracted from their ores using carbon.
- Extracted by using electrolysis of the molten metal compound.


What is salt?

- A compound formed when the hydrogen in an acid is wholly or partially replaced by metal or ammonium ions.


How can salt be made?

- Reacting a suitable metal with an acid.
- Metal must be above hydrogen in the reactivity series but not dangerously reactive.


What happens during a reaction with a metal and an acid?

Hydrogen produced as well as salt.
Sample of salt made can then be crystallised out of solution by evaporating off the water.


What is the reaction between a metal and an acid a reaction of?

- A redox reaction.
- Metal atoms lose electrons and are oxidised and hydrogen ions from the acid gain electrons and are reduced.


What happens when an acid reacts with a base?

- Neutralisation reaction occurs.
- Produces a salt and water.


What does the sum of salt add up to and what does this enable you to do?

- Adds up to 0.
- Work out the formula of salts knowing the charges on the ions is present.


What can you do to a dry sample of salt made in an acid base reaction?

It can be crystallised out of solution by evaporating off most of the water and drying with filter papers if necessary.


When is an indicator needed?

- When a soluble salt is prepared by reacting an alkali with an acid.


Can the experiment between an alkali and an acid be repeated without the indicator?

Yes, to make a pure salt then a pure dry sample of its crystal prepared.


What happens when a carbonate reacts with an acid?

Produces salt, water and carbon dioxide gas.


What are acids?

Substances that produce H+(aq) ions when you add them to water.


What are bases?

Substances that will neutralise acids.


What is an alkali?

Soluble hydroxide.
Alkali's produce OH-(aq) ions when you add them to water.


What is the pH scale used for?

To show how acidic or alkaline a solution is.


How is the pH scale measured?

pH scales less than 7 are acidic, pH values more than 7 are alkaline and a pH value of 7 is neutral.


What do aqueous solutions of weak acids have, such as carboxylic acids?

- Have a higher pH value than solution of strong acids with the same concentration.


What happens when the pH decreases by one unit?

- The hydrogen ion concentration of the solution increases by a factor of 10.