Trivia
What is the official capital of Sri Lanka?
Sri Jayawardenapura Kotte
List 2 Characteristics of a substance that something need to be a primary standard
The secondary structures of proteins are stabilized by this intermolecular force.
What is Hydrogen Bonds
Which one of the following statements BEST describes the function of an anode in an electrolytic cell?
(a) The anode is the electrode at which reduction occurs.
(b) The anode is the only electrode at which OH¯ (aq) ions are produced.
(c) The anode is the electrode which attracts positive ions.
(d) The anode is the electrode that is oxidised.
(d) The anode is the electrode that is oxidised.
Consider the following equilibrium system, which is formed when solid white phosphorus reacts with fluorine gas to form phosphorus trifluoride vapour.
P4(s) + 6 F2(g) ⇌ 4 PF3(g)
What is the correct equilibrium constant (K) expression for the following reaction?
Ans: K=[PF3]^4/[F2]^6
How old is Ms. Pinya in 2023?
48
What is the average amount of titre:
Sample 1: 24.65
Sample 2: 24.86
Sample 3: 25.05
Sample 4: 24.92
29.94
This amino acid can produce the strongest bonds
What is Cysteine
Which of the following statements regarding fuel cells is correct?
(a) Fuel cells are a type of galvanic cell.
(b) Fuel cells are a type of electrolytic cell.
(c) Fuel cells are a type of primary cell.
(d) Fuel cells are a type of secondary cell.
(a) Fuel cells are a type of galvanic cell.
Bromine water, which is a dilute aqueous solution of bromine in water, is slightly acidic because of its reaction with water, represented by the following equation:
Br2 (aq) + H2O (l) ⇌ HBrO (aq) + H+ (aq) + Br – (aq)
In aqueous solution, bromine, Br2 (aq) is brown. Hypobromous acid, HBrO (aq), and bromide ions, Br – (aq) are both colourless.
State and explain the colour changes that would be observed, if the following changes are made to the system at equilibrium.
(a) Addition of NaOH (aq). (3 marks)
Colour: Brown colour fades, or solution turns less brown.
Explanation: Addition of OH- causes a decrease in the [H+] as the combination of the two ions produce water (H2O). This will result in the rate of collision of reactants being greater than that of products, shifting the equilibrium to the right, favouring the forward reaction rate. Thus the [Br2] decreases causing the brown colour to fade.
Who is the best teacher?
Brendan
What is the pH solution given that [H+] = 0.1967
0.706
When an amino acid is in an low pH, this occurs
What is gaining a hydrogen atom
When the reactant for a half cell is a gas, what type of electrode do you use? Why do you use this type of electrode?
An inert electrode, such as platinum or graphite, is used when the reactant is a gas. This is because there is no solid conductor for the gas to conduct electrons through the wire.
In the following equilibrium system, nitrogen, oxygen and chlorine gases combine to produce nitrosyl chloride vapour. This equilibrium system can form at temperatures of around 400 °C.
N2(g) + O2(g) + Cl2(g) ⇌ 2 NOCl(g)
colourless colourless greenish-yellow yellow
If an equal number of moles of N2(g), O2(g) and Cl2(g) were injected into a sealed flask at 400 °C;
Explain what would happen to the forward and reverse reaction rates as the system moved to establish equilibrium.
Which country bears the highest mountain of the world?
Nepal
Potassium hydrogen iodate, KH(IO3)2, is a common primary standard used in acid-base titrations.
A sample of KH(IO3)2(s) weighing 1.218 g was dissolved in distilled water and made up to 250.0 mL in a volumetric flask. 20.00 mL aliquots of this primary standard were taken and titrated against a sodium hydroxide solution, NaOH(aq), of unknown concentration. An average titre of 23.74 mL was required to reach the end point.
The equation for the titration reaction is;
KH(IO3)2(aq) + NaOH(aq) ® NaIO3(aq) + KIO3(aq) + H2O(l)
Q:Calculate the concentration of the NaOH(aq) solution. State your answer to the appropriate number of significant figures.
0.01053M
What are the most prevalent bonds within protein structures
What is Hydrogen, Peptide and Disulphur bonds
Why do lithium-ion batteries get lighter as they lose charge, and heavier when on full charge?
As the reaction takes place, hydrogen gas is produced. Since hydrogen gas is lighter then air, is experiences a buoyant force and thus appears lighter
Aluminium salts are acidic due to the presence of the hexaaqualuminate ion, [Al(H2O)6]3+ which is formed when a soluble aluminium salt is dissolved in water. This ion undergoes hydrolysis as follows:
[Al(H2O)6]3+ (aq) + H2O (l) ⇌ [Al(OH)(H2O)5]2+ (aq) + H3O+ (aq)
A solution of aluminium nitrate has a pH of 5.6.
It was found that when the aluminium nitrate solution was warmed, the pH of the solution decreased. From this information, deduce whether the forward reaction in the above equilibrium is endothermic or exothermic. Explain your reasoning:
As the pH has decreased due to an increase in the [H+], caused by an increase in temp; (1) clearly the Forward reaction has been favoured by this imposed change, (ie. higher temp).
In order for the reaction to respond in this way, (ie. shifting the equilibrium to the right),
the Forward reaction must be ENDOTHERMIC
What year did Ms. Pinya migrate to Australia?
2005
53.70 g of raspberries were liquefied by pulverising and dissolving in an appropriate solvent. The liquid raspberry mixture was made up to 100.0 mL in a volumetric flask. 20.00 mL aliquots were then taken and titrated against a standard 3.802 x 10-3 mol L-1 NaOH solution. The titration equation is given below.
C14H6O8(aq) + 4 NaOH(aq) --> 4 H2O(l) + Na4C14H2O8(aq)
If the concentration of ellagic acid is known to be 40.06 mg per 100.0 g of raspberries;
Determine the theoretical value of the average titre that the professor should obtain. (Assume all sources of error were minimised and ellagic acid is the only compound in the raspberries that reacts in the titration).
14.98 mL
When a protein becomes denatured, this is the cause for its loss of shape
(What is weaking or loss of hydrogen bonds)
The electroplating of various metals plays an extremely important role in industry. These reactions can be carried out on a small scale in the laboratory using standard laboratory equipment.
A typical spoon can be chrome electroplated utilising a chromium electrode and an acidified aqueous chromium nitrate solution. Using a labelled diagram, explain the process involved in electroplating the spoon.
Your answer should pay particular attention to the following areas:
(a) How the cell can be constructed. (A diagram with clear labels for the anode, cathode, electrolyte, direction of flow of electrons and ions).
[on my computer, can show you for answer. Person needs to draw diagram on board]
Nitric oxide is an unstable molecule, and when it comes into contact with ozone the following reaction takes place, producing nitrogen dioxide (NO2) and oxygen (O2).
O3(g) + NO(g) ⇌ NO2(g) + O2(g)
The activation energy for the forward reaction is 10.8 kJ, whilst the activation energy for the reverse reaction is 210.5 kJ.
Considering the activation energy values provided;
Comment on the likely reversibility of this reaction and explain how this would affect the size of the equilibrium constant (Kc):