AS 2017 paper 1 Breadth in Chemistry Flashcards
(27 cards)
Sample of 4 hydrocarbons are completely burnt under the same conditions of temperature and pressure. Which sample produces the greatest volume of C02 ?
0.3 x3 = 0.9
B 0.3 mol
Which reaction produces the smallest atom economy of BaCl2 ?
BaCO3 + 2HCL – BaCl2 + CO2 + H2O
The burette readings from a titration are shown below.
Final reading - 24.95
Initial reading - 5.00
The burette used has an uncertainty of 0.05 cm in each reading.
What is the percentage uncertainty of the resulting titre ?
0.05 x 2 /19.95 x 1000 = 0.50 %
D
Which element has the highest melting point ?
Silicon - has a giant covalent structure - A
Phosphorus
sulfur
chlorine all have a simple covalent structure
What is the best explanation for the trend in boiling points down the halogens group ?
The induced dipole- dipole interactions (London forces) increases.
Which silver compound is insoluble in concentrated NH3 (aq) ?
AgI
50 cm of 1.00 NaOH is neutralised by 50 cm of 1.00 HNO3. The temperature increases by 6.0 C.
The experiment is repeated using 25 of 1.00 NaOH and 25 of 1.00 HNO3.
C 6.0
Its going to be the same because although you’re using half the no. of moles reagent you’ll also use half the amount of water. Therefore the temperature change is the same
H2 (g) + I2 (g) – 2hI(g) /\H = -9.4KJ
Which change in conditions would be expected to shift the equilibrium position towards the products ?
B - Decrease the temperature
Changing the pressure will have no effect at all because you have the same no. of moles of gas on each side
How many structural isomers have the molecular C5H12?
3
Which organic compound has the lowest boiling point ?
2,3,4 trimethylpentane
It needs to be the most branched or most spherical molecule
Which alcohol reacts with an acid catalyst to form E and Z stereoisomers ?
pentan-3-ol
When you dehydrate that you will have different groups on both carbons in a double bond.
The reaction of 2-chloropropene with steam requires a catalyst. State a suitable catalyst for this reaction.
H2SO4/H3PO4
After their useful life, waste polymers can be disposed of by combustion. State 1 particular problem with disposal of poly(2-chloropropene) by combustion. (1)
formation of HCL or chlorine
Calculate the relative atomic mass of the magnesium in the sample. Give your answer to 2dp. (2)
(24 x 78.99) + (25 x 10.00) + (26 x 11.01) /
100 = 24.32
B and C are ionic compounds of 2 different group 1 elements. The molar mass of B and C are both approximately 140.
A student dissolves B and C in water in separate test tubes and analyses the solutions.
Addition of HN03 - B- Bubbles C - no change
followed by BaCl2 B- no change C - white precipitate
Use this information and the observation to identify the formulae of B and C.
Observations linked to anion identifications -Bubbles /effervescence/fizzing/gas AND carbonate - (white OR precipitate) AND sulfate Carbonate: 140 – (12 + 48); 140 – 60 Sulfate: 140 – (32.1 + 64); 140 – 96.1 B= K2CO3 = 138.1 C= Na2SO4 = 142.1 The charge on the carbonate is 2 there must be 2 group 1 ions.
Estimate the energy required to form 1 Na+ ion from one Na atom. Give your answer in KJ, in standard form, and to 2 sf. (1)
500
6.02x 1023 = 8.3 x 10–22 (kJ)
Explain why the 1st ionisation energies … show a general increase across Period 3.(Na-Ar) (3)
There is greater nuclear charge as the no. of protons increase.
The atomic radius decreases because the outer electrons experience the same shielding. There is greater nuclear attraction on outer electrons.
Explain why the general increase in 1str ionisation energies across period 3 is not followed for Mg. (z=12) to Al (z=13) (2)
Mg electron is removed from (3)s and Al electron is removed from (3)p
Energy levels
Al electron has a higher energy
OR (3)p has higher energy than (3)s
Methanol can be prepared industrially by reacting carbon monoxide with hydrogen in the presence of a copper catalyst. This is a reversible reaction.
C0(g) + 2H2(g) – CH30H(g)
Using the boltzmann distribution model, explain why the rate of a reaction increases in the presence of a catalyst. (4)
Curve starts within two small squares of origin and not touching the x axis at high energy
axes labels:
y: (number of) molecules/particles
x: (kinetic) energy
- Catalyst provides a lower activation energy or
- Ec shown below Ea on Boltzmann distribution
- More molecules /particles/collisions have energy
above activation energy (with catalyst) or greater area under curve above activation
energy
Explain why the use of the catalyst reduces energy demand and benefits the environment. (2)
- Lower temperatures/less heat/less thermal energy
- Less fossil fuels/oil/coal/gas/non-renewable fuels
- Reduces CO2 emissions
What is meant by acid and weak acid ?
(Acid) releases H+
ions/ H+ donor
AND
(weak acid) partially dissociates/ionises
Aluminium is reacted with ethanoic acid. balance the equation.
2Al(s) + 6CH3COOH (aq) – 2(CH3COO)3Al (aq)+ 3H2(g)
Deduce which element has been oxidised and which element has been reduced, and state the changes in oxidation number.
Element oxidised: aluminium/Al 0 to +3
Element reduced: hydrogen/H +1 to 0
A studnet plans to determine the conc of CH3COOH in a bottle of vinegar. The student will carry out a titration with aqueous barium hydroxide Ba(OH)2. Method -
- Dilute 10 cm of vinegar from the bottle with distilled water and make the solution up to 250.
- add the diluted vinegar to the burette
- Titrate 25 volume of 0.0450 Ba(OH)2 with the diluted vinegar. (4)
- n(Ba(OH)2) in 25.0 cm3
= = 1.125 x 10–3(mol) - n(CH3COOH) in 25.45 cm3 diluted vinegar= 2 x 1.125 x 10–3 = 2.25 x 10–3 mol
- [CH3COOH] in diluted vinegar = 2.25 x 10–3
x 1000 / 25.45 = 0.0884 - [CH3COOH] in original vinegar = 0.0884 x 250
10.0 = 2.21
Suggest 1 assumption that the student has made that might mean that their calculated conc of ethanoic acid in the vinegar is invalid. (2)
- Vinegar contains (ethanoic acid and) no other acids
- Expermental result is greater than conc of CH3COOH
OR conc of CH3COOH is less than experimental result
