Weaknesses Flashcards
Describe the stages of Paper Chromatography
1) draw a line in pencil near the bottom on the filter paper
2) add a spot of the ink being investigated on the line and place the sheet in a solvent, make sure the solvent isn’t touching the ink
3) place the lid on the container to stop the solvent evaporating
4) each dye with move up the paper at different rates so they will form different spots
What does filtration separate?
Insoluble solids from liquids
What does evaporation separate and how is it completed?
Soluble solids from solutions:
1) pour the solution into an evaporating dish
2) slowly heat the solution until the solvent has evaporated leaving dry crystals
What does crystallisation separate and how is it completed?
Soluble solids from solutions:
1) pour the solution into an evaporating dish
2) once some crystals form, remove the dish
3) the salt should form crystals as it becomes insoluble
4) filter out the crystals and leave them in a warm place to dry
What are the products of an alkali metal and water?
metal hydroxide and hydrogen
What is the product of an alkali metal and chlorine?
Metal chloride slats
What is the product of an alkali metal and oxygen?
Metal oxides
What are the coloured vapours of: Flourine Chlorine Bromine Iodine
yellow
green
red-brown
purple
What are the structure and properties of ionic compounds?
A giant ionic lattice which has high melting and boiling points. Carry an electronic charge when molten or when dissolved in water.
What two types of element bond ionically?
A metal and a non-metal
What two types of element bond covalently?
Two non-metals
What are the properties of giant covalent structures?
Very high melting and boiling points. Don’t conduct electricity, even when molten, apart from exceptions like graphite.
What are the potential uses of fullerenes?
Could be used to deliver drugs in body. Huge surface area could make them good catalysts and they’re good lubricants.
What is the name of the force between the metal ions and the delocalised electrons in metallic bonding
Electrostatic
What are the properties of metals?
Solid at room temp because of strong forces between electrons and ions, good conductors of heat and electricity, maleable.
What is the typical diameter of a nanoparticle?
1-100nm
What is the formula for number of moles?
mass ÷ Mr
What is the formula for the volume of a know mass of any gas at r.t.p?
(mass + Mr) x 24
What is the formula for concentration?
no. of moles ÷ volume
What is the equation for atom economy and what does it tell us?
(relative formula mass of desired product ÷ relative formula mass of all reactants) x 100
It tells us what percentage of the reactants will be made into useful products
What is the equation for percentage yield and what does it tell us?
(mass of product made ÷ maximum theoretical mass) x 100
It compares what we actually have to what the maximum amount we could have is
What does an acid + a base give?
A salt and water
How do you complete a titration?
If you wanted to find the concentration of an alkali:
1) using a pipette, add a set volume (25cm3) of an akali to a conical flask add 2 - 3 drops of phenolphthalein
2) fill a burette with acid of known concentration and record the initial volume
3) add the acid to the alkali slowly.
4) the indicator changes colour (pink to clear) when all the alkali has been neutralised
5) record the final volume of the acid to work out the volume of the acid required to neutralise the alkali
6) use concentration calculations to work out the concentration of the alkali
What happens to strong acids in water?
All acid particles dissociate to release H+ ions
Acid + metal oxide =
Salt + water
Acid + metal hydroxide =
Salt + water
Acid + metal carbonate =
Salt + water + carbon dioxide
What are the first 10 elements in the reactivity series?
Potassium Sodium Lithium Calcium Magnesium Carbon Zinc Iron Hydrogen Copper
Acid + metal =
Salt + hydrogen
Metal + water =
Metal hydroxide + hydrogen
What is the rule for what is formed at the cathode?
If hydrogen is less reactive than the metal, it is formed
What is the rule for what is formed at the anode?
Oxygen with be formed if no halides are present
When is a reaction exothermic?
When the energy released by forming bonds is greater than the energy used to break them
How does a rechargeable cell work?
The reaction can be reversed by connecting it to an external electric current
Why aren’t alkaline batteries rechargeable?
The reactions are irreversible
How can you work out order of reactivity?
Add each unknown metal to the copper sulfate, measure temperature change. Put them in order of temperature change.
What are the products of combustion?
Water + Carbon Dioxide
What are the positives of nanotechnology?
Improvements in medicine, communication and electronics
What are the negatives of nanotechnology?
New technology meaning we don’t know about any side effects
What are the properties of simple molecular substances?
- Low boiling point
- Gas or Liquid at room temperature
- Don’t conduct electricity
How can we measure pH?
- Universal indicator
- pH probe
What do pH units represent?
For every one the pH goes down, the number of H+ ions increases by a factor of ten
When must a metal be extracted by electrolysis?
If it is more reactive than carbon
On an exothermic reaction profile, what has higher energy, the reactants or the products?
The reactants
On an endothermic reaction profile, what has higher energy, the reactants or the products?
The products
In fuel cells, what is the positive electrode called?
The cathode
In fuel cells, what is the negative electrode called?
The anode
What did Rutherford discover?
The nucleus
What did Chadwick discover?
Neutrons
What are group 1 metals known as?
Alkali metals
What are group 7 elements known as?
The halogens
What is the equation for the negative electrode in a hydrogen fuel cells?
2H2 = 4H + 4e-
What is the equation for the reaction at the positive electrode in a hydrogen fuel cell?
O2 + 4H+ + 4e- = 2H2O
