NYGH 2012-S3BT1-Chem

Class Register Number Name 南洋女子中学校 NANYANG GIRLS' HIGH SCHOOL BLOCK TEST 1 Secondary Three CHEMISTRY 1 hour Monday 02 April 2012 1115-1215 h READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write your name, register number and class in the spaces at the top of this page. Section A (Multiple Choice) Section A (15 MCQ) This section consists of 15 multiple choice questions. Choose the best answer and write its letter in the space provided on page 2 of the Question Paper. Section B (Structured) Answer all questions in the spaces provided on the Question Paper. Section C (Free-Response) Answer all questions in the spaces provided on the Question Paper. Submit Sections A, B and C together. INFORMATION FOR CANDIDATES The intended number of marks is given in the brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 12. Topics to be tested: Acids and Bases Salt preparation Ionic equations Qualitative analysis Examiner’s Use Section A (15 marks) Section B (20 marks) Section C (10 marks) Total (45 marks) Setter: Z.J. This document consists of 12 printed pages. NANYANG GIRLS' HIGH SCHOOL [ Turn over]

2012 Block Test 1 Nanyang Girls’ High School Secondary Three Setter: Z.J. Chemistry 2 Section A (15 Marks) Answer the questions (1-15) by filling the answer in the table below. 1 6 11 2 7 12 3 8 13 4 9 14 5 10 15 Section B (20 marks) Answer all questions in this section in the spaces provided B1 Choose from the following list of substances and write the chemical name of the substance that best match the identities of substances L-Q. You may choose to use any substance only once, more than once, or not at all. ammonia carbon dioxide copper(II) nitrate iron(III) carbonate hydrogen nitrogen monoxide potassium carbonate sodium hydroxide zinc (a) Upon addition of aqueous L to aqueous M, a blue precipitate which is soluble in excess aqueous M was observed. [2] L: M: (b) An acidic oxide N was produced upon reaction of insoluble O and dilute hydrochloric acid. [2] N: O: (c) The ionic equation for the reaction of aqueous P with aqueous calcium chloride is: Ca2+(aq) + CO3 2-(aq) → CaCO3(s) [1] P:

2012 Block Test 1 Nanyang Girls’ High School Secondary Three Setter: Z.J. Chemistry [Turn Over] 3 B2 (a) The following reactions were carried out according to the following pathway: + + + (i) Write the ionic equation for the reaction that produced V and W. [2] (ii) Describe what will be observed when aqueous sodium hydroxide is added to solution V. [2] (iii) How would you confirm the identity of the anion in X? Describe the test and state its observations. [3] (b) A student added aqueous silver nitrate to a colourless solution to test for chloride ion. She observed that a white precipitate was formed and concluded that chloride is present. Explain whether her conclusion is valid. [2] Aluminum Dilute sulfuric acid Gas W Solution V Add aqueous barium nitrate Precipitate Y Solution X

2012 Block Test 1 Nanyang Girls’ High School Secondary Three Setter: Z.J. Chemistry 4 B3 (a) The following pH curve was obtained in a titration between aqueous sodium hydroxide and dilute nitric acid. (i) What was the burette filled with? [1] (ii) What is the volume of aqueous sodium hydroxide used for the titration? [1] (b) Another titration was carried out. The end point was reached when 20.00 cm3 of sulfuric acid was added to a conical flask filled with 25.0 cm3 of sodium hydroxide. Assuming that the pH of dilute sulfuric acid was 2 and the pH of aqueous sodium hydroxide was 14, sketch the pH curve for this titration on the same graph in (a). [3] Total volume of mixture in conical flask / cm3 6 pH 10 20 30 40 50 60 70 2 4 8 12 10 14 0 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6

2012 Block Test 1 Nanyang Girls’ High School Secondary Three Setter: Z.J. Chemistry [Turn Over] 5 c) The following pH curve was obtained when aqueous sodium hydroxide was titrated with ethanoic acid. Given the following information, choose a suitable indicator for the titration between sodium hydroxide and ethanoic acid. Indicator pH range at which colour change occurs Methyl orange 3.1-4.4 Phenolphthalein 8.3-10.0 Bromomethyl blue 6.0-7.6 Suitable indicator: [1] pH 10 20 30 40 50 60 70 2 4 6 8 12 10 14 0 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 Total volume of mixture in conical flask / cm3

2012 Block Test 1 Nanyang Girls’ High School Secondary Three Setter: Z.J. Chemistry 6 Section C (10 marks) Answer all questions in this section in the spaces provided C1 (a) A student carried out the following steps to prepare pure and dry crystals of a hydrated salt using the method of acid reaction with excess insoluble carbonate. Step 1: 30cm3 of a hot acid was measured and poured into a beaker Step 2: Excess solid carbonate was added to the acid in the beaker until it no longer dissolves in the acid. Step 3: The mixture was heated for a while and filtered to collect the residue as product. (i) Identify two mistakes in the student’s procedures to prepare the hydrated salt. [2] (ii) Suggest a possible identity for the salt prepared. [1] (iii) State the respective acid and carbonate that should be used to prepare your suggested salt in a(ii). [2]

2012 Block Test 1 Nanyang Girls’ High School Secondary Three Setter: Z.J. Chemistry [Turn Over] 7 (b) Another student wants to prepare pure calcium sulfate salt. (i) Are the procedures in part (a) suitable for the preparation of pure dry calcium sulfate? Explain your answer. [3] (ii) Write a balanced chemical equation with state symbols for a suitable reaction that can be used in the preparation of a pure dry sample of calcium sulfate. [2] END OF TEST

2012 Block Test 1 Nanyang Girls’ High School Secondary Three Setter: Z.J. Chemistry 8 Section A (15 marks) Choose the most suitable answer and write its letter in the answer table provided on Page 2. 1 We say that an acid is a weak acid when A it has a high pH. B it has a low pH. C it dissociates partially in water to form H+ ions. D only one H+ ion is produced per acid