Acid and Metal Reactions Flashcards
What is formed when a metal reacts with water?
Metal hydroxide+ Hydrogen.
What metals in the reactivity series do not react with dilute acids?
Metals below Hydrogen do not react with dilute acids.
Unreactive towards the hydrogen atoms in the solution.
What does a metal + dilute acid produce?
Metal+ Dilute acid - Salt + Hydrogen
What is oxidation?
Gain of oxygen, loss of electrons in a chemical reaction.
Give an example of an oxidation reaction?
Magnesium + oxygen - Magnesium oxide
Give an example of a reduction reaction?
Copper oxide+ carbon - copper + carbon dioxide.
If something has reduced, what ion will it produce?
- Gain electrons.
- Form negative ion.
If something has oxidised, what ion will it produce?
- Loss of electrons.
- Form positive ions.
What is a displacement reaction?
A displacement reaction is when a more reactive metal displaces a less reactive metal from its compounds.
Give an example of a displacement reaction?
Magnesium + copper sulphate - Magnesium sulphate + copper.
What happens when magnesium displaces copper sulphate solution?
- The magnesium becomes coated with copper.
- Blue colour fades and colourless into colourless magnesium sulphate solution.
How can you deduce a reactivity series?
- Metal dipped in salt solution to see displacement reaction.
What is a redox reaction?
A redox reaction is when oxidation and reduction happen at the same time.
How do you work out the formula of an ionic compound?
- Make sure the charges are equal to 0.
What is the formula of Sulphuric acid?
H2SO4
What is the charge on a nitrate ion?
NO3 -
What is meant by pH?
The level of hydrogen ions in an acid.
What is the formula for ammonium?
NH4 (+)
What is the charge on a sulphate ion?
SO4 2-
What is the charge on a carbonate ion?
CO3 2-
What is the charge on a hydroxide ion?
OH-
Where are most metals extracted from?
- Most metals are extracted from an ore.
- Ore: A rock that contains enough metal to make extracting it worthwhile.
How can a substance be extracted from its compounds by heating with carbon?
- Any elements less reactive than carbon.
- Heated with carbon.
Eg. Copper oxide + Carbon —– Carbon dioxide + copper. - Molten copper is formed.
What does molten mean?
Molten is a term to describe a liquid substance.
What is a mineral?
A mineral is a naturally occurring element or compound.
What does malachite ore have in it?
- Malachite ore has copper(II Carbonate) in it.
What does cinnabar have in it?
- Cinnabar ore has mercury(II sulphide) in it.
What do most metals exist as?
- Sulphides.
- Oxides.
- Carbonates.
What does limestone have in it?
- Calcium carbonate.
What does hematite contain?
- Iron (III) Oxide.
What are electrolytes?
- Electrolytes are substances, when melted/ dissolved, will conduct an electric current.
Why is aluminium oxide mixed with cryolite before the electrolysis process?
- It lowers the melting point so less energy is needed.
- Reduced energy, saves money.
What is the positive electrode in electrolysis?
- The positive electrode in electrolysis is the graphite anode.
- This attracts the negative ions (eg. O2-, from aluminium oxide.)
What is the negative electrode in electrolysis?
- The negative electrode in electrolysis is the graphite cathode.
- This attracts positive ions eg. (Al 3+, from aluminium oxide.)
What is electrolysis?
- Electrolysis is the decomposition of a compound using an electric current.
- Large amounts of it can be expensive.
Why are the cathodes and anodes made of graphite?
- It can conduct electricity.
- High melting points (withstand high temperatures.)
Explain, with the half equation, how oxide ions are oxidised during the electrolysis of aluminium oxide?
The half equation is: 2O2- → O2 + 4e-. It shows that oxide ions lose electrons, and oxidation is loss of electrons.
Explain, with the help of a half equation, how aluminium ions are reduced during the electrolysis of aluminium oxide?
The half equation is: Al3+ + 3e- → Al
It shows that aluminium ions gain electrons, and reduction is gain of electrons.
Why do you need to double the oxygen half equation?
- The oxygen atoms pair up to make an oxygen molecule at the anode.
How do you test for hydrogen?
- Light a split, put it in a sample of wherever hydrogen is present.
- A squeaky pop noise means hydrogen is present.
- If not, there will be no change.
What is a base?
- A base is a substance that reacts with an acid to form salt and water.
What types of bases are also alkali?
- Bases that are soluble in water.
Give the neutralisation reaction.
- Acid +base — Salt +water
Explain why all alkalis are bases, but not all bases are alkali.
- Only bases that are soluble (dissolve in water) are alkali.
- All alkalis are bases
What is produced when an acid reacts with a carbonate?
Acid + carbonate — salt + water + carbon dioxide
How can you make a soluble salt?
- You can make a soluble salt by having an insoluble reactant react with an acid.
Give examples of insoluble reactants that produce salt.
- Metal
- Metal oxide
- Metal hydroxides
- Carbonates
What is the method of producing a soluble salt from an insoluble reactant?
- Add powdered insoluble reactant to a beaker with acid. Keep adding until it is in excess. All the acid mixed with reactant.
- Filter the mixture in the beaker to get rid of any solid. Now should be salt+ water only.
- Heat the solution in an evaporating basin over a water bath. Stop heating when it is halfway. Small crystals should form. It is now saturated.
- Pour the rest of the solution in a watch glass
- Leave the saturated solution for two days to allow crystals to form.
What does saturated mean?
- Saturated means unable to have any liquid.
What is an endothermic reaction?
- One that takes in energy from its surroundings.
- The energy of surroundings decrease.
- Feels cold
- Energy of products is more than energy of reactants.
What is an exothermic reaction?
- One that releases energy into its environment.
- The temperature of the surrounding increase.
- Energy of reactants more than products.
- Feel hot.
What is an energy level diagram?
- The energy level diagram shows the energy of reactants and products, and the difference between them.
What are the metals in the reactivity series?
Lithium, Potassium, Barium, Calcium, Sodium, Magnesium, Aluminium, CARBON, Zinc, Iron, Nickel, Tin, Lead, HYDROGEN, Copper, Mercury, Silver, Gold, Platinum.
What is meant by “concentration?”
- Concentration is the mass per unit volume.
What happens if the pH of a solution decreases by 1 unit?
- If the pH of a solution decreases by 1 unit it means that the concentration of ions increases by a factor of 10. Eg. x100 x 1000
Why does copper not react with sulphuric acid?
- Copper is lower than HYDROGEN in the reactivity series.
- It will be unable to displace the HYDROGEN in a reaction.
What is a salt?
- A salt is the substance formed when the hydrogen ion in an acid is replaced by a metal ion.
When can you measure the pH of a substance?
- You can measure pH when the substance is dissolved in water.
