grade 12

8.1 Learners set up a galvanic cell and measure its emf under standard conditions. 8.1.1 Write down the name of component Y. (1)8.1.2 Is Al the ANODE or the CATHODE? (1)8.1.3 Write down the overall (net) cell reaction that takes place in this cell when it is working. (3)8.1.4 Calculate the initial emf of this … Read more

7.1 Ammonia ionises in water to form a basic solution according to the following balanced equation: 7.1.1 Is ammonia a WEAK or a STRONG base? Give a reason for the answer. (2)7.1.2 Write down the conjugate acid of NH3(g). (1)7.1.3 Identify ONE substance in this reaction that can behave as an ampholyte in some reactions. … Read more

Carbonyl bromide, COBr2, decomposes into carbon monoxide and bromine according to the following balanced equation: COBr2(g) ⇌ CO(g) + Br2(g) ∆H > 0 Initially COBr2(g) is sealed in a 2 dm3 container and heated to 73 °C. The reaction isallowed to reach equilibrium at this temperature. The equilibrium constant for thereaction at this temperature is … Read more

A group of learners uses the reaction between powdered zinc and EXCESS dilute hydrochloric acid to investigate one of the factors that affects the rate of a chemical reaction. The balanced equation for the reaction is: Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) They conduct two experiments. The reaction conditions used are summarised in the … Read more

The flow diagram below shows how an alcohol (compound P) can be used to prepare other organic compounds. The letters A to E represent different organic reactions. X, Y and Z are organic compounds. 4.1 Is compound P a PRIMARY, SECONDARY or TERTIARY alcohol? Give a reason for the answer. (2) 4.2 Write down the … Read more

The vapour pressure versus temperature graph below was obtained for four straight chain (unbranched) alkanes (P, Q, R and S).FROM P TO S, EACH COMPOUND DIFFERS FROM THE PREVIOUS COMPOUND BY A –CH2 GROUP.The vapour pressures are measured in mmHg. Atmospheric pressure is 760 mmHg. 3.1 Give a reason why alkanes are said to be … Read more

2.1 Study the structural formula below. For this compound, write down the:2.1.1 Homologous series to which it belongs (1)2.1.2 IUPAC name (2)2.1.3 IUPAC name of the organic acid used in its preparation (1)2.1.4 STRUCTURAL FORMULA of its straight chain (unbranched) functional isomer (2) 2.2 Write down the structural formula of 4-methylpentan-2-one. (3) 2.3 Consider the … Read more

1.1 The IUPAC name of an organic compound with molecular formula C7H14O2:A HeptanalB Heptan-1-olC Heptan-2-olD Heptanoic acid (2) 1.2 Which ONE of the following structures is the functional group of aldehydes? 1.3 Which ONE of the following equations represents a cracking process? 1.4 The potential energy diagram for a chemical reaction is shown below. I: … Read more