Mixed Exam Questions Flashcards
Suggest one advantage of adding cyclohexane to hexane in petrol
Cyclohexane will burn more efficiently
Explain what is meant by the term stereoisomers
Compounds with the same structural formula but a different arrangement (of atoms) in space
Chemists have developed ways of removing hydrogen chloride from these waste gases.
Sodium hydrogencarbonate, NaHCO3(s), is frequently used in industry for this purpose.
Explain how sodium hydrogencarbonate removes hydrogen chloride.
Sodium hydrogencarbonate neutralises HCl
Explain the following statements, using equations where appropriate.
Life on Earth benefits from the presence of an ozone layer.
The concentration of ozone is maintained in the ozone layer.
Compound G produces radicals which catalyse the breakdown of ozone.
Ozone absorbs Uv light
Maintained in equilibrium
O3 -> O2 + O
Cl. + O3 –> ClO + O2
ClO. + O –> Cl. + O2
Radical substitution produces a mixture of organic products.
Suggest two reasons why.
different termination products
substitution at different positions along chain
Waste poly(hex-1-ene) can be disposed of usefully by recycling.
State two other methods of disposing of polymers that can be beneficial to the environment.
Combustion for energy production
Use as organic feedstock
How many orbitals are occupied in a silicon atom
8
What is the shape around the carbon atoms in graphene
Trigonal Planar
Students intends to remove the water by heating the hydrated salt
Suggest one modification that the student could make to their method to reduce the percentage error in the mass of water removed
Use a balance weighing to 3 or more decimal places
The student is not sure that all the water of crystallisation has been removed
How could the student modify the experiment to be confident that all the water of crystallisation has been removed?
Heat the constant mass
What conditions are needed to heat alkene into hydrocarbon
Hydrogen and Nickel Catalyst
What is the reactant when h2so4/ h3po4 and heat Is used to produce alkene
Alcohol
Explain why the first ionisation energy of strontium is less than the first ionisation energy of calcium
An extra shell is added so more shielding and less nuclear attraction. Atomic radius has increased
What are the two equations to show how NO radicals catalyse the breakdown of ozone
NO. + O3 => NO2. + O2
NO2. + O => O2 + NO.
Predict the C-O-H bond angle and explain the shape
104.5 degrees
Oxygen has 2 bond pairs and 2 lone pairs which repel
Lone pairs repel more than bond pairs
State one problem with disposal of poly(2-chloropropene) by combustion
Can go to incomplete combustion
Chlorine is produced
What are the tests for carbonate and sulphate
Add HNO3 and if there’s effervescence then carbonate is present
Add BaCl2 or Ba(No3)2 and if white precipitate then sulphate present
Explain why first ionisation energy shows a general increase across Period 3
Atomic radius decreases
Nuclear Charge increases therefore greater nuclear attraction
Explain why the use of the catalyst reduces energy demand and benefits the environment
Lowers the temperature
Reduces CO2 emissions
Explain why the trend in boiling points increase in halogens
Number of electrons increase
More London forces
More energy required to break the intermolecular forces.
There is a sample of ammonium bromide
Describe simple tests that would identify the cation and anion present in ammonium bromide
Include reagents, expected observations and equations
To test for cation - ammonium
Use a litmus paper and heat with NaOH the paper should turn from red to blue.
NH4 +OH→NH3+H2O
To test for anion - bromide
Add silver nitrate and the precipitate should change turn a cream precipitate
Ag+ + Br- => AgBr
What is the formula for silver carbonate
Ag2CO3
What are the number of electrons in the 1,2,3,4 shell
2
8
18
32
Outline 2 reactions routes for preparing Ba(OH)2 from barium in the lab
Ba + 2H2O –> Ba(OH)2 + H2
2Ba + O2 –> 2BaO
BaO + H2O –> Ba(OH)2
What is the equation for the reaction of Carbonate
2H+ + CO3 2- –> CO2 + H2O
For dynamic equilibrium does concentration need to be equal in both forward and backward reaction
No
Plan an experiment on a test tube scale that would show the trend in the reactivity of the halogens CL2, Br2, I2
Get three testubes with the solutions , Cl2, Br2, I2 in cyclohexane
Then add NaI to all three of the test tubes
Halogen displacement reaction should occur.
Cl2 + I- –> 2Cl- + I2 Pale green to violet
Br2 + I- –> 2Br- + I2 Orange to Violet
What is the reagent from Haloakane to Alcohol
NaOH (aq)
State the shape and bond angle for SF6
Shape - Octahedral
90 degrees
A stufen plans to prepare solution of magnesium nitrate starting from magnesium nitration crystals
Describe how the student would prepare the solution, giving full details of quantities apparatus and method
The student would measure the weight of the crystals using a balance and to 2.d.p
Then they would dissolve the crystals in distilled water
Transfer this to a 250cm^3 volumetric flask
Rinse beaker and final washings
Fill with distilled water to the mark
Stopper and invert mixture
When alkene becomes bromoalkane
What observation is made
Orange to colourless
What is meant by the term standard solution
Solution of a known concentration
