KERBOODLE PRACTICE QUESTIONS: WM Flashcards
How many esters are there with formula C4H8O2?
A) 1
B) 2
C) 3
D) 4
D) 4
HCOOC3H7 has two isomers, one with branching in the chain
Which pair of compounds would react to form CH3COOH3?
A) CH3CH2OH and HCOOH
B) CH3OH and (CH3CO)2O
C) CH3COOH and CH3CH2OH
D) CH3Cl and CH3COOH
B) CH3OH and (CH3CO)2O
What will be the main product when propan-1-ol is distilled with acidified dichromate?
A) CH3COCH3
B) CH3CH2COOH
C) CH3CH2CHO
D) CH3CH2CH2OH
C) CH3CH2CHO
distillation produces mostly aldehyde
A student is recrystalising a solid using water as a solvent. The solid is dissolved in the minimum of hot water and allowed to crystallise
Which is the correct sequence that follows?
A) wash with water, filter, and dry the crystals
B) remove the wet crystals and let them dry on a hotplate
C) filter the crystals and dry them
D) filter the crystals, wash, and dry
D) filter the crystals, wash, and dry
all other sequences will involve solutions of impurities evaporating on the crystals
Which of the following sequences would work for purifying a liquid organic product?
A) wash, separate, dry, distill
B) disill, wash, separate, dry
C) separate, dry, wash, distil
D) dry, distill, wash, separate
A) wash, separate, dry, distill
Which of the following is not true about a mass spectrum?
A) The M+1 peak is caused by impurities
B) The M+ peak indicates Mr of the compound.
C) Peaks of smaller mass are caused by fragments of the molecule
D) Only positive ions are detected
A) The M+1 peak is caused by impurities
The M+1 peak is caused by the presence of C13
In which of the following answers does the name correctly describe the formula?
A) (CH3CO)2O = ester
B) CH3CHO = ketone
C) CH3OCH3 = ether
D) CH3COCH3 = acid anyhdride
C) CH3OCH3 = ether
CH3COOH can be made by the oxidation of which of the following:
- *Number 1:** CH3CHO
- *Number 2:** CH3CH2OH
- *Number 3:** CH3COCH3
A) 1,2 and 3 are correct
B) 1 and 2 are correct
C) 2 and 3 are correct
D) Only 1 is correct
B) 1 and 2 are correct
A substance that fizzes when added to aqueous sodium carbonate could be:
- *Number 1:** a carboxylic acid
- *Number 2:** a phenol
- *Number 3:** an alcohol
A) 1, 2 and 3 are correct
B) 1 and 2 are correct
C) 2 and 3 are correct
D) Only 1 is correct
D) Only 1 is correct
Which of the following is/are correct about a tertiary alcohol?
- *Number 1:** It cannot be oxidised using acid dichromate
- *Number 2:** It will form esters
- *Number 3:** It can be dehydrated
A) 1, 2 and 3 are correct
B) 1 and 2 are correct
C) 2 and 3 are correct
D) Only 1 is correct
A) 1, 2 and 3 are correct
Some students set out to make a sample of aspirin.
They react salicylic acid with ethanoic anhydride, using a phosphoric acid catalyst.
Complete the equation for the reaction by drawing out the skeletal structures of the products.
Some students set out to make a sample of aspirin.
They react salicylic acid with ethanoic anhydride, using a phosphoric acid catalyst.
The impure product is filtered off, washed, and dried, and its melting point taken.
Name the method of purification that the students would use
Recrystalisation
Some students set out to make a sample of aspirin.
They react salicylic acid with ethanoic anhydride, using a phosphoric acid catalyst.
The impure product is filtered off, washed, and dried, and its melting point taken.
After purification how would the melting point change (if at all)?
Higher than before
Some students set out to make a sample of aspirin.
They react salicylic acid with ethanoic anhydride, using a phosphoric acid catalyst.
The students start with 10.0g of salicylic acid and finish with 5.0g of purified product. Calculate the percentage yield.
n(salycilic) = 10/138
(= 0.0725 mol)
max. mass aspirin = 10 x 181/138 (= 13.12 g)
% = (5 x 100/13.12) = 38%
Some students set out to make a sample of aspirin.
They react salicylic acid with ethanoic anhydride, using a phosphoric acid catalyst.
The students use thin layer chromatography to check they have made aspirin and to see if there is any unreacted salicylic acid in the sample of aspirin. Give details of their method.
beaker with solvent and TLC plate
spots of their sample and salicylic acid and aspirin on plate
run chromatogram
examine spots at the same level to see what is present in their sample
solvent starts below spots
sample, salicylic acid and aspirin all in solution (in ethanol)
cover beaker for run
use uv or iodine to locate spots
Which of aspirin and salicylic acid will react with neutral iron(III) chloride? Give your reason and state the colour of the positive test
salicylic acid (only)
phenol
purple colour
Write the equation for the reaction of salicylic acid with sodium carbonate, using structural formulae for organic substances
The students titrate 1.05g of their purified aspirin with sodium hydroxide.
24.70cm3 of 0.100 mol dm-3 NaOH was required
Calculate the purity of the aspirin assuming that one mole of aspirin reacts with one mole of NaOH under these conditions
n(NaOH) = 24.7 x 0.1/1000 (= 2.47 x 10<sup>–3 </sup>) n(aspirin) = 2.47 x 10<sup>–3</sup> x 180 (= 0.445 g) % = 0.445 x 100/1.05 = 42.3%
The students titrate 1.05g of their purified aspirin with sodium hydroxide.
24.70cm3 of 0.100 mol dm-3 NaOH was required
Assume that one mole of aspirin reacts with one mole of NaOH under these conditions. How might NaOH react with aspirin under other conditions?
both –OH and –COOH
form salts
The students titrate 1.05g of their purified aspirin with sodium hydroxide.
24.70cm3 of 0.100 mol dm-3 NaOH was required
Which impurity, if present in aspirin would invalidate results for the calculation of the purity of aspirin?
salicylic acid (or any named acid)
Butan-2-ol is an intermediate in the industrial formation of ‘MEK’, a widely used solvent
Classify butan-2-ol as a primary, secondary, or tertiary alcohol, giving a reason.
Secondary
C bearing OH is attached to two Cs OR has one H attached
Butan-2-ol is an intermediate in the industrial formation of ‘MEK’, a widely-used solvent.
Give the reagents and conditions that would be used in a laboratory to make MEK from butan-2-ol
acid dichromate
heat or reflux
Butan-2-ol is an intermediate in the industrial formation of ‘MEK’, a widely-used solvent.
Draw the structure of MEK and name its functional group
CH3COC2H5
Ketone
Butan-2-ol is an intermediate in the industrial formation of ‘MEK’, a widely-used solvent.
A chemist takes a sample from the plant making MEK from butan-2-ol and runs the infrared spectrum shown below.
Explain the conclusions the chemist can draw about the progress of the reaction.
partial conversion
both –OH and –C=O present
O-H absorption around 3400
C=O absorption around 1700
Butan-2-ol is an intermediate in the industrial formation of ‘MEK’, a widely-used solvent.
A chemist runs a mass spectrum of butan-2-ol, Two of the peaks obtained are 74 and 75 (very small)
GIve the type of ion responsible for each peak
74: M+
75 (very small): M+1
Butan-2-ol is an intermediate in the industrial formation of ‘MEK’, a widely-used solvent.
A chemist runs a mass spectrum of butan-2-ol, Two of the peaks obtained are 74 and 75 (very small)
Other peaks are found at m/z values below 74. How do these form?
M+ ion fragments into other ions
A compound A gives just butan-2-ol when it reacts with water.
Give the full structural formula for compound A
Angles not important
A compound A gives just butan-2-ol when it reacts with water.
Butan-2-ol can be dehydrated in the laboratory to a mixture of compound A and one other compound
Give the reagents and conditions for this reaction
Then give the skeletal formula of the other compound that is formed
pass vapour at 300 C (±50)
over alumina
OR conc sulfuric acid
Reflux
