Chem Practical Planning Questions with Anskey

Pei Hwa Secondary School Secondary 4 Pure Chemistry 6092 Practical: Planning Question Practices Name: ………………………………… ( ) Class / TG : …………… Date: ……………….… 1 1 X is zinc powder contaminated with carbon. Plan an experiment to purify X and determine the percentage purity of X. You can assume all the apparatus and reagents normally found in a school laboratory are available. In your method you should note any other assumptions that you make, include the measurements you would take and explain how you would use your results determine the percentage purity of X. …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………[5]

2 2 Eggshells and cockleshells are some common substances that contain calcium carbonate. However, the percentage by mass of calcium carbonate in each of these substances varies. (a) Outline a method you could use to determine whether an eggshell or a cockleshell contains a higher percentage by mass of calcium carbonate. You can assume all the apparatus and reagents normally found in a school laboratory are available. You should include in your answer the measurements you would take, and explain how your results would show which type of shell contain a higher percentage by mass of calcium carbonate. …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………[5] (b) State an assumption that is made in the experimental method outlined in 2(a). …………………………………………………………………………………………………… …………………………………………………………………………………………………[1]

3 3 Metal carbonates undergo thermal decomposition to produce metal oxides and carbon dioxide. The more reactive a metal is, the more difficult it is to decompose its carbonate. You are required to plan an experiment to determine the order of the reactivity of the metals calcium, copper and zinc by comparing the relative ease of decomposition of calcium carbonate, copper(II) carbonate and zinc carbonate. You are only provided with samples of the three metal carbonates and no other chemical reagents. You can assume all the apparatus normally found in a school laboratory are available for your investigation. Your plan should include a list of quantities that remain constant, measurements to be taken, and how your results would determine the reactivity of the given metals. You may wish to use a labelled diagram to illustrate your answer. …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………[5]

4 4 Agricultural limes are mixtures of calcium carbonate and calcium oxide. Farmers use agricultural limes on fields to neutralise acidity. Plan an investigation to find out which of the two different agricultural limes, Q or R, will neutralise more acid. You are provided with common laboratory apparatus and chemicals. In your method, you should include the measurements you would take, and explain how your results can be used to determine which agricultural limes, Q or R, will neutralise more acid. …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………[4]

5 5 When provided with a bottle of aqueous sodium carbonate of unknown concentration, there are many methods other than thermometric titration, which can be employed to determine its concentration. Outline a method by which the concentration of aqueous sodium carbonate can be determined. You can assume that all the apparatus and reagents normally found in a school la boratory are available. In your method you should note any assumptions that you make, include the measurements you would take and explain how you would use your results to calculate the concentration of aqueous sodium carbonate. You may not use a method involving temperature change. [Ar: H, 1; Cl, 35.5] ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ……………………………………………………………………………………………………… [5]

6 6 You are required to investigate the effect of concentration of hydrochloric acid on the rate of reaction. You are only provided with hydrochloric acid of three different concentrations and magnesium strips. You can assume all the apparatus normally found in a school laboratory are available. You should include in your answer • an outline of the method used, • the measurements you would take, and • explain how your results can be used to determine the effect of concentration of acid on rate of reaction. You may wish to use a labelled diagram to illustrate your answer. ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ……………………………………………………………………………………………………… [5]

7 7 You are provided with three bottles of colourless solutions; one contains dilute hydrochloric acid, another contains aqueous sodium nitrate and the third contains aqueous sodium sulfide. You are also provided with two pieces of information: 1. Sulfide ions can be oxidised to form sulfate ions. 2. Most barium salts are soluble in water except barium carbonate and barium sul