Revision Flashcards
(43 cards)
A student uses this apparatus ( chromatography) to investigate colours in four different inks A,B,C,D. The baseline is drawn in ink and submerged in the water, and the water is high explain two mistakes the student made in this investigation
- Baseline is drawn in ink instead of pencil, the pencil does not interfere with the results but the ink mixes with the other samples of ink
- The baseline is submerged into the water and has depth, allowing the ink samples to be washed away
What happens if one of the ink is tested in insoluble water ( chromatography)
- will not travel up the chromatography and will take the longest time to travel up
What is the equation or the Rf value and hat is one think you might do to make sure thus is accurate
- Rf value equation is distance trialled by the substance divided by the distance travelled by the solvent
- measure from baseline as spits may elongate
Explain why helium is now used in airships instead of hydrogen
- inert
-hydrogen is easily flammable
A displacement reaction can be used to decide the order of react it between two metals, state two observations made when an excess of magnesium powder is added to an aqueous solution of copper (11) sulfate
-pinky brown solid forms
-solution turns colourless
Explain why diamond is hard but graphite is soft
- diamond is hard because make of 3D lattice
-graphite contains layers of differently sized molecules that are able to slide over each other ad make it soft
Explain why silicon dioxide has a high melting point
- giant covalent lattice structure
-strong forces of attraction between molecules that require a lot of hat energy to break
Show chemical test for unsaturated ( alkene) and saturated ( alkane) molecules
- bromine water
- if Alkene- decolourise orange
- if alkane- stay orange
What is an isomer
- atom with same molecular formula but different structural formula
What is an isotope
Atom with same number of protons but different number of neutrons
Pentane reacts with bromine in the presence of ultraviolet radiation- explain what type of reaction this is
Substitution
Diagram shows methane burning in air. It also shows how the two gases formed are collected and tested
Explain why water is collected in the U-tube
- water vapour condenses because it is cooled but he ice and water
Chemical test for water
- anhydrous copper sulfate- if water present turns blue if not stays white
The student uses a grunted beaker to measure the volume of the dilute hydrochloric acid, explain why it is not necessary to use a measuring cylinder in this experiment,
- acid is in excess no need for accurate measurement
The ionic equation shows the reaction between magnesium and hydrochloric acid.
Mg [s] + 2H(1+)[aq] —> Mg (2+) [aq] + H2
Use the information from this equation and the particle collision theory to explain why the rate of reaction decreases during each of these experiments
- as concentration o H+ ions increase- so does rate of reaction. The less H+ ions the less frequent collisions there are occurring in second per unit volume.
Identify a method to eperate water from copper (11) sulfate solution
Simple distillation
What is a compound
Both atoms or elements chemically combined to each other
Chemical name for rust
Hydrated iron (111) oxide
Some iron objects are coated with a layer of zinc to prevent rusting, what types of rust prevention is this?
- galvanising
Give a reason why copper powder is heated in experiment to find the percentage of oxygen in a gaseous mixture
- give particles enough energy to react
Give the name of the black powder that forms when oxygen reacts with copper
- copper (11) oxide
Suggest one reason why the calculated percentage of oxygen in the mixture may not be accurate
Temperature not the same
Explain why sodium oxide does not conduct electricity
- giant ionic lattice
- no delocalised electrons
Give an advantage in creating pure, dry crystals of sodium nitrate of mixing solutions containing equal amounts in moles of silver nitrate and sodium chloride
- to ensure highest possible yield
