Exam-style multiple choice and written questions with full markschemes. Check multiple choice answers straight away, or type, photograph or draw a written answer and get it marked.
A student uses a calibrated pH meter to measure an aqueous ethanoic acid solution. Figure 1 shows the meter reading.
State the pH of the solution shown in Figure 1.
Calculate the hydrogen ion concentration, [H⁺], in the solution. Give your answer in mol dm⁻³ to two significant figures.
At room temperature, of magnesium ribbon is added to excess dilute hydrochloric acid. Figure 1 shows the measured volume of gas collected over time.
Use Figure 1 to state the volume of gas collected after
Write a balanced equation, including state symbols, for the reaction of magnesium with dilute hydrochloric acid.
In a voltaic cell, electrode A undergoes the reaction
Identify electrode A as the anode or cathode and state its sign.
In an electrolytic cell, electrode B undergoes the reaction
Identify electrode B as the anode or cathode and state its sign.
Ethane reacts with bromine under ultraviolet light. Bromoethane is one product, and the reaction proceeds by a radical chain mechanism.
Write the two propagation equations for the reaction of ethane with bromine.
Write a termination equation involving two ethyl radicals.
State one reason why a mixture of organic products can form.
State two features of alkanes that contribute to their low reactivity.
Chlorine reacts with propane when irradiated with ultraviolet (UV) light. Figure 1 shows the displayed structural formula of propane.
Determine the number of different monochlorinated structural isomers that can form from propane.
Write the equation for the initiation step, using single-barbed arrows to show the movement of electrons.
For the formation of 2-chloropropane:
Write the first propagation equation, in which a hydrogen atom is transferred from propane to a chlorine radical.
Using the propan-2-yl radical, CH₃CH•CH₃, write the second propagation equation.
Write one equation for a termination step in this chain reaction.
Boron trifluoride forms a 1:1 adduct with ammonia:
Reaction I: BF₃ + NH₃ → BF₃·NH₃
A proton reacts with water to form a hydronium ion:
Reaction II: H⁺ + H₂O → H₃O⁺
Identify the electrophile in reaction I and state which reactant supplies both electrons in the new B–N bond.
Identify the electrophile in reaction II and explain the origin of both electrons in the new O–H bond.
A student claims that an electrophile must be positively charged. Assess this claim using both reactions.
Boron trifluoride reacts with ammonia to form a boron-containing adduct. A sample initially contains of Ammonia is added in measured amounts, and the amount of adduct formed is determined.
The following two stages occur when propanone reacts with cyanide ions in the presence of hydrogen cyanide:
In the product of the first stage, the carbon atom of is bonded to the carbon atom that was part of the carbonyl group.
Use Figure 1 to estimate the amount of at which the amount of adduct formed first becomes approximately constant. Hence, deduce the stoichiometric ratio of to in the adduct.
Write an equation for the formation of the adduct, showing the coordinate bond, and identify the Lewis acid and Lewis base.
State why the formation of the adduct in (b) is not a Brønsted–Lowry acid–base reaction.
A student claims, “Since each stage in the propanone reaction involves an electron-pair donor and an electron-pair acceptor, both stages must also be Brønsted–Lowry acid–base reactions.”
Annotate the two stages with curly arrows to show electron-pair movement. Identify the Lewis acid and Lewis base in each stage, and evaluate the student’s claim.
Unlock every question in this topic, then type, photograph or draw your answer and have it marked against the markscheme. Find out where you are dropping marks.