Unit 3 AoS 1
Ethanol is a biochemical fuel that is increasingly being used as an alternative or additive to petroleum-based fuels for cars and trucks.
Which of the following processes is used to produce commercial quantities of ethanol for use in cars and trucks?
A) fermentation of glucose from crops such as corn and sugar cane.
B) fractional distillation of crude oil.
C) reaction of vegetable oils and animal fats with methanol.
D) decomposition of organic waste by bacteria under anaerobic conditions.
A.
Why does a reaction require a certain amount of energy in order to be initiated?
The energy is required to break the bonds in the reactants to allow new bonds to form and create products.
Draw the structure of 3-methylbutanoic acid
CH3CH(CH3)CH2COOH
Are these titres concordant:
24.65ml, 24.55ml, 24.60ml
yes
Scientific posters communicate the findings in investigations.
Which section of a scientific poster should explain the reasoning for undertaking the investigation?
Introduction
A calorimeter was calibrated electrically using a voltage of 3.3V and a current of 1.6A for 2 minutes. The temperature of the water in the calorimeter increased by 1.1oC
The calorimeter's Calibration factor is:
A) 8.14 JoC-1
B) 489 JoC-1
C) 576 JoC-1
D) 592 JoC-1
C
2 minutes in seconds
Consider the following reaction:
2H2(g) + O2(g) --> 2H2O(g) ΔH = -484 KJmol-1
Which of the following is likely to decrease the rate of the reaction:
A) increasing the volume of the reaction vessel
B) increasing the temperature at constant volume.
C) increasing concentration fo the reactants at constant temperature.
D) adding a catalyst.
A: all gases and increases pressure
One moles of an organic compound reacts with exactly 2 mol of oxygen gas to produce 2 mol of carbon dioxide gas and 2 mole of water.
The organic compound could be:
A) Ethene
B) Ethanol
C) Ethanoic acid
D) Ethane
C
CxHyOz + 2O2 --> 2CO2 + 2H2O
Consider the following data:
Formula: C3H6O2
IR spectrum: sharp band near 1720 cm-1
1H NMR spectrum: two singlet peaks at 2.1ppm and 3.7ppm
Which one of the following organic compounds is consistent with the data?
A) 2-propanol
B) methyl ethanoate
C) propanoic acid
D) propanamine
B
Using large sample sizes in an experiment increases:
A) reliability
B) precision
C) validity
D) uncertainty
A
The efficiency of the energy conversion occuring in an octane-fuelled combustion engine is determined to be 26.0%
Based on this finding, whihc one of the following statements is correct?
A) Only 26.0KJ of the chemical energy in each full tank of fuel is converted to usable energy in the combustion engine.
B) When a tank of fuel undergoes combustion, exactly 74.0% of the chemical energy is converted to heat energy.
C) The combustion engine converts chemical energy to mechanical energy efficiently to propel the car.
D) for every 2000KJ of energy contained in the fuel, 520KJ of usable energy is released on combustion in the engine.
D
Explain why increasing temperature increases the rate of a reaction involving gases.
higher the temperature, the average speed of molecules (kinetic energy) increases, giving more molecules sufficient energy to overcome the activation energy barrier allowing more successful and frequent collisions to occur. This results in a fast reaction rate.
Draw an isomer of C4H10O. Provide its IUPAC name
any isomer with the correct IUPAC name
A student conducted a redox volumetric analysis. They pipetted a 20.00ml aliquot of a victamin C solution into a conical flask. They added a 0.050M solution of iodine to the conical flask from a burette. A titre of 19.0ml was obtained, but the student had expected a titre closer to 20.0ml
Which of the following could account for the unexpectedly low titre that was obtained?
A) The conical flask was rinsed with water prior to titration
B) The burette was rinsed with water immediately prior to being folled with the iodine solution.
C) The 20.0 ml pipette was incorrectly calibrated and actually delivered 20.1ml of the vitamin C solution.
D) The 20.0ml pipette was rinsed with water immediately prior to being used.
D
Scientists typically repeat experiments many times before reporting their findings.
This ensures that the experimental results are:
A) more certain because systematic errors are reduced.
B) more certain because random errors are removed.
C) more precise because a correct procedure is used.
D) more precise because all variables are controlled.
B
When experiments are repeated, random errors are eliminated but not any systematic errors dur to faulty equipment.
Each of the following contains phosphorous
In which compounds does phosphorous have a different oxidation number when compared to the other compounds.
A) P4O8
B) P2O5
C) PO43-
D) H2PO4-
A (+4) others a +5
Consider the following reaction:
4HCl(g) + O2(g) ⇔ 2H2O(g) + 2Cl2(g) ΔH < 0
Which of the following changes would increase the yield of Cl2?
A) removing oxygen from the system at constant volume.
B) adding an inert gas such as argon.
C) adding a suitble catalyst.
D) Increasing the gas pressure.
D: shifts to the side with less particles
Why should atom economy be considered when designing new industrial processes?
Make AE as high as possible to avoid waste products as these require additional energy and expense for disposal
Two tests were conducted to establish the identity of a liquid organic compound. The compound reacted with solid sodium carbonate to evolve a colourless, odourless gas. When bromine was added to the compound, a reaction occured that produced a colourless product.
The compound is most likely
Propanoic acid
In a fuel cell, CH3OH reacts according to the following half-equation:
CH3OH(g) + H2O(l) --> CO2(g) + 6H+(aq) + 6e
If the cell operates with a current of 100mA for 5 minutes, calculate the maximum mass of CH3OH that will react.
(ne-) = It/F = 0.1 A x (5x60)/96500 = 3.1088x10-4
(1/6)x(ne-) = 5.1813x10-5 mol
m(ethanol) = 5.1813x10-5 x 32 = 1.66x10-3 or 0.00166 g
The following represents an experimental arrangement of a cell for the electrolysis of an aqueous solution of three metal sulfates.
0.1M Zn2+ 0.1M Cu2+ 0.1M Ni2+
The half equations for the initial reactions occuring at the cathode and anode.
2H2O(l) --> O2(g) + 4H+(aq) + 4e (anode)
Cu2+(aq) +2e --> Cu(s) (cathode)
If the cell operates for a long time, it is observed that hydrogen gas (H2) is evolved at the cathode and that the cathode is coated with zinc (Zn) and nickel (Ni)
In what order would H2, Zn and Ni be produced at the cathode?
Ni, Zn, H2
A secondary alcohol was placed in an acidified solution containing a dilute acid. The compound 2-pentanone.
What was the secondary alcohol?
Pentan-2-ol
Pure plant oils can be used to produce biodiesel. A pure plant oil's iodine number can be used to determine the identity of the oil. The iodine number is the number of grams of iodine that react with 100g of a substance, such as an oil.
A 10g sample of a pure plant oil that is used to make biodiesel was shaken vigorously with 100.0ml of a solution containing 15g of iodine. After the reaction was complete, 2.01x10-2 mol of iodine remained in the solution.
What is the iodine number of the plant oil?
99
m(iodine) unreacted= 2.01x10-2 mol x (126.9x2) = 5.101g
m(iodine) reacted with 10g sample = 15-5.101= 9.89g
m(iodine) reacted with 100g of sample = 9.89 x 10 = 98.9 = 99