TMA4/CHM192

My TMA Home TMA Results My Pending TMA Quick Help TMA Quiz Questions TMA: TMA4/CHM192 Matric Number: SCORE=10.00 sep 2016 CHM192 - Introductory Chemistry Practical II Miss Abdul Modupe (mabdul@noun.edu.ng ) 1 The principal purpose of extraction is ___________. To recover a substance from a mixture To sublime a substance To activate a substance None of the above 2 The boiling point of methanol is ______________. 65oC$${65}^{o}C$$ 78oC$${78}^{o}C$$ 97oC$${97}^{o}C$$ 69oC$${69}^{o}C$$ 3 Which equipment can be used for a fire? Band-aid Fire quencher Fire blanket Fire extinguisher 4 Which of these properties is considered during recrystallization process? Temperature Mass Volume Density 5 A cube of copper was found to have a mass of 630 g. What are the dimensions of the cube given the density of copper to be 8.94 g/cm3. 70.47 cm 8.39 cm 4.13 cm 8.26 cm 6 Why is ethanol not a suitable solvent for extracting aqueous solutions? Due to its high boiling point Due to its solubility in water Due to its flammability All of the above 7 Freezing points are difficult to determine because of the phenomenon of ___________ Impurities Refridgeration Supercooling None of the above 8 What is the meaning of "oiling out" during recrystallization? Compound melts before dissolving Compound dissolves before melting Compound turns to oil Compound sublimes 9 Insoluble impurities have ______________ effect on the melting pont. little no maximum minimum 10 Which of the following is helpful in establishing the purity of a compound? Boiling point Sublimation point Decomposition point All of the above 11 The phenomenon whereby solids pass directly from the solid state to the gaseous state is termed ___________ Sublimation Evaporation Fractional distillation Recrystallization 12 Mercury is traded by the "flask", a unit that has a mass of 34.5 kg. What is the volume of a flask of mercury if the density of mercury is 13.6 g/ml? 200 ml 2350 ml 2537 ml 1970 ml 13 What is the boiling point of ethanol at 720 mm Hg when its normal point at 760 mm Hg is known to be 78.3 o C 75.3oC$${75.3}^{o}C$$ 76.3oC$${76.3}^{o}C$$ −3oC$${-3}^{o}C$$ −2oC$${-2}^{o}C$$ 14 Which of these best describes a phenomenon whereby a solid suddenly shrinks before melting? Sublimation Shrinking Sintering Evaporation 15 How many layers are usually formed in a separating funnel? 4 3 2 1 16 Which of the following features decreases boiling point? Polarity Molecular weight Branching None of the above 17 What is the effect of a small amount of impurity on the melting point of an organic compound? Decreases melting point Elevates melting point Stagnates melting point None of the above 18 You are given a bottle that contains 4.59 cm3 of a metallic solid. The total mass of the bottle is 35.66 g. The empty bottle weighs 14.23 g, what is the density of the solid? 4.67 g/cm3 8.94 g/cm3 3.1 g/cm3 None of the above 19 What is the effect of a small amount of impurity on the boiling point of an organic compound? Decreases boiling point Elevates boiling point Stagnates boiling point None of the above 20 Which of these is not a useful physical property used to identify an organic compound? Density Odour Basicity UV spectrum