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VRAAG 5 5.1 Jy besluit om ‘n titreringseksperiment uit te voer om die konsentrasie van ‘n monster kaliumhidroksied te bepaal.  Gegee die volgende gebalanseerde vergelyking: KOH(aq) + HCl(aq)

QUESTION 6 0,5mol H2(g) and 0,6mol Br2(g)  is combined in a 5.0dm3 flask and heated to 700 K. The reaction is exothermic : H2(g) + Br2(g) → 2HBr(g) 6.1 The concentration of HBr in the flask at equilibrium is 0.17 mol.dm-3. Calculate  Kc. (8) 6.2 When the temperature is increased, will the Kc value INCREASE, DECREASE or STAY THE SAME? Use Le Chatelier’s principle to explain your answer. (4) 6.3 Consider the following graph and answer the questions that follow:   Right click on the following blue button to open the images for QUESTION 6, in a new tab.       6.3.1 Write a balanced equation that represents the exothermic reaction that takes place. (3) 6.3.2 Give the time (s) when the system reaches equilibrium. (2) 6.3.3 Name the disturbance that occurred at 14 s. (2) 6.3.4 How will the value of the equilibrium constant after this disturbance change? Write only INCREASE, DECREASE or STAY THE SAME. Give a reason for your answer. (3) 6.3.5 Name the conditions necessary for the reaction to reach equilibrium. (2) 6.3.6 Name one other condition that will affect the equilibrium in this reaction and explain what the effect will be on the Kc-value if this condition increases.  (3)     [27]

1.2 Voltooi die volgende sin: Volgens die VSPER-teorie rangskik valens-elektronpare hulself so dat hulle so __________ is as wat hulle kan wees. (2)

1.8 A sample of hydrocarbon contains 82.75% carbon per mass. The empirical formula of the compound will be _____. (2)

Question 3   3.1 Look at the four different molecules shown in the diagram linked below and answer the questions that follow.   Right click on the button below to open the image in a new tab     3.1.1 Which one of the four molecules can exhibit hydrogen bonding among other molecules of the same type? Give the chemical formula. (1) 3.1.2 Give the IUPAC name for the molecule you chose in 3.1.1. (1) 3.1.3 Give the common name for the molecule you chose in 3.1.1. (1) 3.2 Explain why the molecule you chose in question 3.1.1 will form hydrogen bonds with other molecules exactly like it while the other molecules will not. (3) 3.3 Name the type of intermolecular force that the other three molecules in the diagram will undergo with other molecules of their own type. Give a reason. (3) 3.4 Which of the four compounds represented by the molecules in the diagram will have the highest boiling point? Explain your answer. (3) 3.5 Draw a diagram of the intermolecular forces between three H2S molecules, indicating polarities. (2)     [14]

1.3 Kies die onderstaande chemiese formule wat ‘n voorbeeld is van ‘n trigonale piramidevormige molekuul. (2)

TOTAL SECTION B: [80] GRAND TOTAL: [100]

1.2 All organic molecules contain at least one atom _____. (2)

  Question 5   5.1 You decide to undertake a titration experiment in order to find the concentration of a sample of potassium hydroxide. Given the following balanced equation: KOH(aq) + HCl(aq) → KCl(aq) + H20(l)   30 cm3 of a 0,2 mol·dm−3 hydrochloric acid solution was reacted with potassium hydroxide. It was found that 22 cm3 of the potassium hydroxide was needed to neutralise the acid.   5.1.1 Convert any necessary units to SI units. (2) 5.1.2 Calculate the concentration of the potassium hydroxide. (4) 5.2 Calcium oxide is a useful compound in industry. It is used to purify sugar, to soften water and in the glass and porcelain making process. 30g of CaCO3 is heated to produce CaO CaCO3 → CaO + CO2   5.2.1 What is the maximum mass calcium oxide that could be produced in this reaction? (5) 5.2.2 However, only 13g of CaO is produced. Calculate the percentage yield. (3)     [14]