[QUESTIONS] KMM SMARTCHEM PRE PSPM 2024-25

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Kolej Matrikulasi Perlis**We aren't endorsed by this school

Course

KIMIA 1

Subject

Chemistry

Date

Dec 19, 2024

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SULIT SK015 SK015 Chemistry 1 Semester I Session 2024/2025 2 hours Kimia 1 Semester I Sesi 2024/2025 2 jamCHEMISTRY UNIT KOLEJ MATRIKULASI MELAKA SMARTCHEM 2 CHEMISTRY 1 2 hours JANGAN BUKA KERTAS SOALAN INI SEHINGGA DIBERITAHU DO NOT OPEN THIS QUESTION PAPER UNTIL YOU ARE TOLD TO DO SO INSTRUCTIONS TO CANDIDATE: This question paper consists of 5 questions. Answer all questions. All steps must be shown clearly. Use a new page for each question. Maximum marks awarded are shown in brackets at the end of each question or section. The use of electronic calculator is permitted. Kertas soalan ini mengandungi 7halaman bercetak. This booklet consists of 7 printed pages.

SULIT SK 015 1 1 (a) FIGURE 1 shows the mass spectrum of element K: Figure 1 Based on the mass spectrum above, calculate the relative atomic mass of K. [3 marks] (b) Valproic acid, is used to treat bipolar disorder and its composed of C, H and O. A 0.165 g sample of valproic acid is combusted to produce 0.166 g of water and 0.403 g of carbon dioxide. Determine the empirical formula of valproic acid. [6 marks] (c) A solution is prepared by dissolving 14.50 g of calcium chloride, CaCl2in 86.0 g of water. The solution formed has a density of 1.07 gmL-1. Calculate the molarity of the CaCl2solution. [4 marks] (d) The reaction between zinc powder with hydrochloric acid, HCl, produces zinc chloride, ZnCl2and hydrogen gas. Zn (s) + 2HCl (aq)ZnCl2(s) + H2 (g)In a reaction between 0.25 g of zinc and 160.00 mL of 0.50 M HCl, 0.40 g of ZnCl2is produced. i.Determine the limiting reactant in the reaction. ii.Determine the percentage yield of the reaction. [8 marks]

SULIT SK 015 2 2. a) Figure 2 shows the series of hydrogen emission spectrum in ultraviolet region. Figure 2 i.Calculate the energy emitted to produce the third line in the series. ii.Determine the wavelength of line B in nm. [4 marks] b) The set of quantum numbers for 3 electrons with the highest principal quantum numbers in atom X are shown below: (n= 4, l = 0, m = 0, s = + 1/2) (n= 4, l = 0, m = 0, s = - 1/2) (n= 4, l = 1, m = 0, s = + 1/2) i. Write the electronic configuration of stable ion X. ii. Sketch the shapes of orbital occupied by the electrons with the highest principal quantum number in atom X. [3 marks] c) Copper is the ninth element in the first row of transition element with a proton number of 29. Write the electronic configuration of the copper atom. Give reason for the anomalous electronic configuration of copper. [3 marks] 3. a) Three resonance structures of cyanate ion, OCN-are shown below. i. Draw the structural formula of structure B and calculate its formal charge. ii. Determine the most plausible structure of cyanate ion. [4 Marks] C D A B

SULIT SK 015 3 b) The valence orbital diagrams of the SF4molecule shown below. Based on the valence orbital diagram: S (ground state) :3s 3p S (exited state) :3s 3p 3dS (hybrid state) :sp3dF (ground state) :2s 2p i. Draw the orbital overlapping of SF4molecule. ii. Determine the polarity of the molecule. [6 marks] c) Compare the boiling point of BH3and NH3. Explain your answer based on intermolecular forces. [4 marks] d) Magnesium is a good electrical conductor. By using band theory, explain the electrical conductivity in magnesium. [3 marks] 4. a) Ammonium nitrate NH4NO2decomposes upon heating to form nitrogen gas. NH4NO2(s)N2(g) + 2 H2O (l)When a sample of NH4NO2is decomposed, 511 mL of nitrogen gas is collected over water at 25 oC and 745 torr total pressure. Calculate the mass of NH4NO2 decomposed. [4 marks] b) Table 1 show a vapour pressure of acetone is higher than methanol at 25oC. Explain. Table 1 Vapour pressure (torr) Acetone, C3H6O 230.0 Methanol, CH3OH 94.0 [3 marks]

SULIT SK 015 4 c) Figure 4 shows the phase diagram of water. Figure 4 The phase diagram shows negative slope of BC line. Explain. [2 marks] 5. a) Based on the following reaction: NH4HS (s) NH3(g) + H2S (g) Kc = 8.50 x 10-3 At 30 oC, the laboratory provides 0.083 mol of NH4HS, 0.076 mol of NH3and 0.045 mol of H2S in 0.500 L evacuated flask. i. Determine the direction of reaction to achieve equilibrium. ii. Calculate the equilibrium constant, Kpof the reaction. [7 marks] b) NH4NO2(s)N2(g) + 2 H2O (l)Based on the above reaction, equilibrium constant, Kcof the reaction is 5.9 x 10-3at 25oC and 7.3 x 10-3at 45oC. Explain whether the forward reaction is endothermic or exothermic reaction. [2 marks]

SULIT SK 015 5 6. a) Table 2 shows Kbvalues of four solution at 25 oC. Table 2 Base KbAmmonia, NH31.8 x 10-5Hydrazine, N2H41.2 x10-6Pyridine, C5H5N 1.6 x 10-9Aniline, C6H5NH27.4 x 10-10i. Choose the most basic solution. ii. Write a dissociation equation of (i). iii.Calculate the pH of 0.2 M of the most basic solution. [7 marks] b) In an experiment, the reaction below occurs when the indicator just change its color. KOH (aq) + HCN (aq)KCN (aq) + H2O (l)i. Predict the pH of the solution at the end point. ii. State the suitable indicator for this titration. [4 marks] c) Calculate the molar solubility of calcium hydroxide, Ca(OH)2in water. [Ksp Ca(OH)2: 6.5 x 10-6] [3 marks]